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A History of Plant Pathology in Virginia: The Moore Era (7/1/1984-3/31/1997)
When Moore became Interim Department Head on July 1, 1984 and Department Head on July 1, 1985, tobacco research and extension at Blacksburg ended. Thereafter, all tobacco projects were completely controlled by personnel at the Southern Piedmont Agricultural Research and Education Station at Blackstone. Plant pathology research was managed by John J. Reilly; extension by D. A. Komm. However, during Moore's interim tenure, Reilly and Komm resigned; Reilly on December 31, 1984, and Komm on January 31, 1985. Hiring a replacement became the joint function of the Station Director, James L. Jones, and Moore.
At a tobacco station, much of the extension activity occurs in mid-winter when growers and County Agents are appraised of new technologies and implored to implement disease control practices on schedule. Field research activities begin early in the calendar year, especially planning experiments, lining up grower-cooperators, and fumigating seed beds. Thus, it was essential to hire replacements as soon as possible. However, hiring procedures for state employees is not a speedy matter. Meanwhile, the decision was made to eliminate one position in plant pathology, to combine into one appointment the duties of both the extension and research position, and to add to the position research and extension in weed science. The position was not filled until September 1, 1985, when Charles S. Johnson was appointed Assistant Professor. It appears that plant pathology research and extension had been squeezed down to the early Reilly period before the hiring of Komm. Actually, plant pathology had been further rendered trivial because the plant pathologist also needed to be a weed scientist. Thus, it may be said that Johnson had to fill two shoes, create two more, and fill them, also. Johnson was capable of doing so and has done a credible job. The 1992 Comprehensive Review gives his assigned distribution as 60% research and 40% extension.
Johnson earned a B.S. degree at the University of North Carolina, 1979; M.S., 1982; and Ph.D. 1985, both the latter at North Carolina State University. His thesis and dissertation were entitled, TMV crop loss methodology in flue-cured tobacco. M.S. Thesis, North Carolina State Univ., 1982. The role of partial resistance in the management of Cercospora leafspot of peanut in North Carolina, Ph.D. Dissertation, N.C.S.U., 1985.
On assuming his duties at Blackstone, Johnson addressed a broad array of disease problems in his extension project, but emphasized research on cyst and root knot nematodes. He did, however, devote attention to the long-standing problems of blue mold, black shank, and bacterial diseases. In the 1992 Comprehensive Review, Johnson stated his goals were to develop concepts and strategies of disease management that would maximize farm profits while minimizing harm to the environment. He would aggressively investigate alternative disease control methods to improve pest management. He listed three specific objectives:
(1) To identify an economic threshold for tobacco cyst nematodes.
(2) To develop practical systems for predicting the incidence, severity, and economic consequences of tobacco disease problems such as cyst and root knot nematodes, black shank, bacterial wilt, and blue mold.
(3) To Identify flue-cured tobacco genotypes resistant and/or tolerant to tobacco cyst nematodes.
Most of the research pertaining to these three objectives was supported by grant funds from the Virginia Bright Flue-Cured Tobacco Board.
In his extension project, Johnson focused on educating county agents to deliver timely programs to growers. He also diagnosed plant diseases, made field calls to aid agents with unusual problems, coordinated a blue mold warning and control system for Virginia, conducted small plot and on-farm test demonstrations of disease, nematode (and weed) control practices, up-dated extension publications on an annual basis, and discussed disease and nematode management at grower meetings, agribusiness training sessions, and pesticide applicator certification meetings. Johnson's research and extension objectives were essentially the same in the 2000 Comprehensive Review, but were more succinctly stated.
Several extension publications that were updated annually contained disease management information. These were:
Flue-Cured Tobacco Production Guide, Publ. 436 - 048.
Flue-Cured Tobacco Variety Information, Publ. 436 - 047.
Dark-Fired Tobacco Production Guide, Publ. 436 - 049.
Dark-Fired Tobacco Variety Information, Publ. 436 - (?).
Burley Tobacco Production Guide, Publ. 436 - 050.
Burley Tobacco Variety Information, Publ. 436 - 417.
Diseases and Nematodes of Tobacco, Pest Management Guide, Publ. 456 - 014.
The 2000 Pest Management Guide presents a 16-page guide to tobacco disease and nematode management. Sections include crop rotations, disease control for greenhouse tobacco, nematode diseases and chemical controls, plant bed diseases, foliar diseases in the field, root diseases, diseases for which there are no chemical controls, lists of disease-resistant varieties of flue-cured, burley, and dark-fired tobacco. Surprisingly noticeable is the virtual absence of Virginia-bred varieties among the flue-cured and burley lists, although there have been active breeding programs in Virginia for these types for more than 60 years. Among 32 flue-cured varieties, the only Virginia-bred variety listed is VA116. Virginia-bred varieties are well represented among dark-fired varieties, 6/11 of those listed.
One of the problems with disease-resistant varieties has been to combine good resistance with good leaf quality. Experiment stations and extension services formerly recommended crop varieties to growers after thoroughly testing available varieties. A variety was "recommended" when it was shown to produce the best yield of acceptable quality. This was fine when most varieties originated at experiment stations, but now that so many are of private origin, varieties are no longer recommended, but after testing they are thoroughly described and the growers choose those that best suit their needs. This procedure was probably brought about to avoid discrimination against any one commercial tobacco seed provider. However, not all growers are astute enough to choose appropriately from variety descriptions; they require assistance from county agents and the staff at the Blackstone station.
Much of Johnson's research effort addresses the biology and management of cyst and root-knot nematodes. This involved evaluating effects of rotations, soil fumigation, chemicals, and use of resistant cultivars on tobacco production. A brief review of some of Johnson's research publications is presented below.
In an attempt to maximize farm profits while minimizing damage to the environment, Johnson, Komm, and Jones explored the effects of rotating resistant and susceptible tobacco cultivars (cvs.) and alternating these rotations with nematicide treatments. They pointed out cyst-nematode-resistant cvs. are difficult to cure and not as productive, therefore, not as profitable to grow as were susceptible cvs. As the population of nematodes increased, resistance became less effective and because the resistance mechanism was hypersensitivity. This means at low nematode populations, a few infection sites resulted in minor damage to the root system. A plant could overcome the root loss by initiating new roots above the infection site. In essence, resistant cvs. were actually tolerant of nematodes. At high populations, however, numerous hypersensitive reactions were so destructive that root regeneration was overwhelmed and leaf production was reduced. Thus, a nematicide was needed at high populations because resistant cvs. were not profitable. Johnson et al. observed that rotation with non-susceptible (insusceptible) hosts reduced tobacco cyst nematode populations, but was not as profitable as continuous tobacco. They obtained the most profitable level of production by growing resistant cvs. For 2 years and fumigating concurrently with fenamiphos, followed by one year of a susceptible cv. with no nematicide (J. Nematol. 21:16 - 23, 1989.).
Johnson, in a paper entitled "Managing root-knot on tobacco in the Southeastern United States" (J. Nemat. Suppl. 21 (4S):604 - 608, 1989.), reviewed the research that had led to the current (1989) procedures for controlling root-knot. Management was dependent upon several practices utilized annually, namely, crop rotations, destruction of crop debris (esp. roots), growing resistant cvs., and applying nematicides. In addition, nematode advisory programs (which assess the potential for damage by determining the population level) may enhance profitability through wiser, conservative use of nematicides. Most of the research forming the basis of this review had been conducted in North Carolina prior to 1984.
Johnson extended the research on rotating cyst nematode resistant and susceptible cvs. of tobacco to show in the first year resistant cvs. reduced the population of Globodera tabacum solanacearum and it was feasible to grow a susceptible cv. in the second year. The population built up so rapidly in the second year that it was necessary to return to a resistant cv. in the third year. If fenamiphos were applied in the second year, a susceptible cv. would be more profitable in the third year (J. Nematol Suppl. 22 (4S):700 - 706, 1990.).
In an experiment which three nematicide treatments (fenamiphos alone, fenamiphos + chlorpyrifos, and fenamiphos + ethoprop) were applied broadcast at two locations to control tobacco cyst nematodes, fenamiphos alone reduce egg numbers, but other treatments did not. Although all increased yield at both locations, the return was not economically significant (Phytopathology 80:671 - 672, 1990.).
At low levels, tobacco cyst nematodes were reported by Johnson to stimulate the yield of flue-cured tobacco. Correlations for cyst eggs per 500 cm3 of soil were negative for plant height, leaf number, and leaf area. Regression analyses indicated that at low levels there were 5.95 and 7.5 kg/ha gains for yield in 1990 and 1991 (Phytopathology 82:1095, 1992.). This could be a dangerous procedure for increasing profits from growing tobacco.
A graduate student, Jie Wang, completed a dissertation in 1996 entitled, "Characterizing resistance in flue-cured tobacco to Globodera tabacum solanacearum." Johnson and J. D. Eisenback were his co-advisors. Wang reported root exudates from both resistant and susceptible plants had similar effects as stimulants of nematode hatching. Tests conducted at several temperatures indicated an optimum range of 25 - 30° C. Infection suppressed number of leaves, plant height, and fresh weight of leaves and feeder roots. Resistant cultivar NC 567 was not as productive as susceptible K 326 in the absence of nematodes. Infection by nematodes had similar effects on both cvs. Resistance is expressed after infection, but is a damaging process; however, since reproduction is prevented by the resistant cv., the nematode population is decreased by growing a resistant cv. in infested soil. Wang, Johnson, and Eisenback summarized this research in a pair of publications (J. Nematol. 29:484 - 490, 1997; 31:326 - 333, 1999.).
It had been reported earlier that genes conditioning resistances in flue-cured tobacco to wildfire (Pseudomonas syringae pv. tabaci) and tobacco cyst nematode (G. tabacum solanacearum) were closely linked, and that by conducting the simpler test for reaction to wildfire, selection for resistance to the nematode could be facilitated. A graduate student, A. J. Hayes, in Crop and Soil Environmental Sciences (formerly Agronomy Dept.) working at Blackstone, evaluated the wildfire test for effectiveness in detecting new sources of cyst nematode resistance. Hayes found high correlation of resistance to both pathogens in some tobacco accessions, but a poor correlation in others. He concluded that screening for wildfire resistance is not a reliable procedure for detecting cyst nematode resistance (Hayes, C. A. Wilkinson, and C. S. Johnson. 1997. Evaluation of tobacco accessions for resistance to tobacco cyst nematode and wildfire. Crop Sci. 37: 586 - 591.).
Johnson et. al. continued research on the tobacco cyst nematode into the Hatzios era and reported that isolates from different sources were pathogenically similar. Consequently, a single isolate would suffice to screen germplasm for resistance (S. L. Rideout, Johnson, Eisenback, and Wilkinson. 2000. Development of selected tobacco cyst nematode isolates on resistant and susceptible cultivars of flue-cured tobacco. J. Nematol. 32:62 - 69.).
Johnson published numerous reports on his work with tobacco fungicides and nematicides. These formed the basis for annual revisions of extension publications. References to these publications are listed here:
Fungicide and Nematicide Tests. 1988. 43:173, 174, 175, 176; 1990. 45:163, 164, 165, 166; 1991. 46:194 - 195; 1992. 47:166; 1993. 48:185, 186, 187.
Additional research on various tobacco nematodes, their morphology and biology appears more fittingly in the section on Nematology.
There was a dissertation completed in 1985 by L. P. Specht entitled "Inoculum densities of Thielaviopsis basicola in tobacco fields in Virginia, and the relationship of inoculum density to the severity of black root rot and growth of tobacco." In order to analyze precisely the relationship between propagule density and root rot effects, Specht initially developed a new medium for isolating T. basicola from soil and roots. Called TB-CEN medium, it contained etridiazol and nystatin to inhibit growth of undesired fungi, and unautoclaved extract from carrot to selectively enhance the growth of T. basicola. Although population densities were similar in burley, flue- and sun-cured regions, burley tobacco plants were more severely affected. Imazalil completely inhibited T. basicola in agar media at 1.0 /micrograms a.i./ml, but failed to control black root rot when added to transplanting water in concentrations as high as 1500/micrograms a.i./ml. Specht and his advisor, G. J. Griffin, published three papers on the dissertation research (Can. J. Plant Pathol. 7:438 - 441, 1985; 10:15 - 22, 1988; Pl. Dis. 71:876 - 879, 1987.).
Cereal pathology research underwent a change in approach during the Moore Era. Since 1947, C. W. Roane had worked with corn and small grains breeders to produce disease-resistant inbred corn lines and small grains cultivars and to study the inheritance of reactions to pathogens.
His career was winding down as was that of his cooperating small grains breeder, T.M. Starling. Corn breeding per se had already ceased and Roane was completing a genetic study. New faculty were appointed with directives to exploit other avenues of research. Erik Stromberg and R.E. Baldwin undertook evaluating the feasibility of chemical disease control in cereal crops, and Stromberg was to evaluate and exploit various plant disease control measures in the intensive wheat culture methods. When Roane's work with Starling ended and Starling retired in 1988, Stromberg elected, or was directed, not to cooperate in the breeding program with his replacement, C.A. Griffey. Breeding and genetic research with maize dwarf mosaic virus also ended. Stromberg devoted himself almost exclusively to control of corn gray leaf spot. In addition, since Stromberg had a 60% extension, 40% research commitment, he felt compelled to carry out a total extension-research program that would produce results quickly. The chemical approach looked most promising.
In his retirement, C.W. Roane collaborated with his wife, Martha K. Roane, to collect and identify graminicolous fungi in Virginia. Three papers were published; the first dealt with fungi associated with cereals (Va. J. Sci. 45:279-296, 1994.). Others followed in 1996 and 1997 (Va. J. Sci. 47:197-224; 48:11- 45.).
Corn - During the 1980's, virus diseases and gray leaf spot (GLS) of corn commanded attention. The two viruses, maize dwarf mosaic virus (MDMV) and maize chlorotic dwarf virus (MCDV) had been largely conquered by the seed corn industry. Most commercial hybrids had been bred with a high level of MDMV and MCDV resistance or tolerance. Nevertheless, the overwintering host of these viruses, johnsongrass, was spreading and its populations were intensifying. The viruses commanded continuing attention of breeders; all new hybrid releases had to be resistant, and from various tests it appeared that they were.
At the beginning of the Moore Era, Roane was studying the genetics of reaction to MDMV. With Tolin and corn breeder C.F. Genter, he had published that monogenic resistance occurred in the inbred line Oh7B (Phytopathology 73:845-850,1983.). By then, Genter was the breeder for a commercial seed company in North Carolina. His replacement was Harold S. Aycock who wished to continue the genetics of virus reactions. Although Roane retired in August 31, 1986, he continued the work until 1989 when Roane, Tolin, and Aycock published two papers on the work. In the first, they report that reaction to MDMV was conditioned by single, allelic genes in the inbred lines B68, Oh1EP, Oh7B, and Va85. The gene was labelled Rmd1 (Phytopathology 79:139 -1368, 1989.). In the second paper, Rmd1 was shown to be linked with genes for endosperm color and texture, y1 and su2, respectively, on chromosome 6. A map of the region was published as rmd117y140su2. The distances were calculated from F2 data (Phytopathology 79:1368- 1372, 1989.). The results were corroborated by a study done at Wooster, Ohio by M.D. McMullin and R. D. Louis who used restriction fragment length polymorphism (RFLP) analysis. (Phytopathology 78:1543, 1988; Molecular Plant-Microbe Interactions 2:309 - 314, 1989.). It was very satisfying to obtain almost identical results with such diverse methods. The studies described above brought genetic research on MDMV to a halt at V.P.I. & S.U.
For the period 1965 - 1988, the corn breeders C. F. Genter and H. S. Aycock, and P. J. Donahue and pathologist Roane had cooperated to test corn inbred lines, hybrids, and promising germplasm for reaction to MDMV and MCDV. Of the two, MCDV had been determined to be the most destructive, but it was severe only in close proximity to johnsongrass. Field testing where both viruses infected corn was done on the farm of Cliff Wood at Wingina, Nelson Co. Mechanical inoculations were executed at Blacksburg. Thus, it was determined that MCDV virtually sterilized any plant it infected early and stunted plants infected during elongation. More than likely, MCDV-infected plants had been previously infected with MDMV as aphids were more efficient at spreading MDMV than leaf hoppers were at spreading MCDV. Early dual infections were very destructive. From this on-farm study, researchers were able to advise farmers which hybrids could be profitably grown in johnsongrass infested fields.
Erik Stromberg continued the work of screening corn germplasm for resistance to viruses. He relied on artificial inoculation with MDMV and depended on opportunistic occurrences of MCDV. The results from these tests were published annually in the Pest Management Guide (Va. Coop. Ext. Serv. Publ. 456 - 011, & 456 - 16, rev. ann.).
In the Agronomy Department (renamed Department of Crop and Soil Environmental Science about 1990), P. J. Donahue completed an M.S. degree; his thesis was entitled "Diallel study of stalk rot resistance in elite maize and its interaction with yield" (Donahue, P. J.; M.S. Thesis, V.P.I. & S.U., 1986.). Elite lines were defined as those in wide use in commercially available hybrid corn varieties.
Stalk rot has been a problem in corn production from the beginning. Several organisms cause it, but the most damaging in Virginia are Diplodia maydis (now Stenocarpella maydis) and Fusarium moniliforme. Donahue artificially inoculated plants with the two organisms by inserting infested toothpicks into the third internode above the ground. Although disease scores were significantly higher in diseased than in control stalks, yield differences were not significant. General combining ability effects were significant for stalk rot scores but not for yield. Two Virginia inbred lines Va17 and Va85 produced high yields and high levels of stalk-rot resistance. These lines were bred in the Genter-Roane era of corn breeding. Usually rotted stalks have well-filled ears; when rotted stalks break and their ears are out of reach of the combine, rot makes an impact on yield. The method used by Donahue would not reflect this because all stalks were harvestable (See also Donahue, Stromberg, and Roane, Va. J. Sci. 40:157 - 170, 1989.).
Upon completing the M.S. degree, Donahue's adviser, H.S. Aycock who was the corn breeder, resigned and Donahue was appointed Maize Project Coordinator until 1987. Then he was elevated to Extension and Research Associate and served in this position until 1989. He and Stromberg collaborated on MDMV and GLS projects until his departure in 1989. Donahue was the last true corn breeder at V.P.I. & S.U. He functioned as such while completing a Ph.D. program.
Stromberg joined with Donahue to evaluate the resistance to MDMV (and GLS) of 14 "elite" inbred corn lines in a diallel cross. Plants were scored for reaction to virus at anthesis and afterward. Various statistical procedures were applied to the scores and agronomic traits. Resistance to MDMV was found to be additive and highly heritable. However, yield and virus scores were negatively correlated (r = - 0.179*), albeit with low significance. The results were based on a two-year study in Montgomery Co., 1987 and 1988, and they became the basis of Donahue's Ph.D. dissertation. Surprisingly, no attention was paid to the fact that Roane, Tolin, and Aycock (Phytopathology 79:1364-1368, 1989.) had reported two lines, B68 and Va85, to have monogenetic dominance for MDMV resistance. How would this affect a diallel study and the conclusions therefrom?
Gray leaf spot (GLS) of corn caused by Cercospora zeae-maydis became a subject of intensive research during the Moore Era. Roane and plant breeders earlier had sought to identify hybrids and inbred lines with high resistance to GLS, but had found only moderate resistance. Moderate resistance did not function well in nurseries where surrounding suscepts produced outpourings of spores which overwhelmed moderate resistance. As a consequence, no satisfactory resistance was identified by Roane and the breeders.
Stromberg had joined with Donahue to evaluate resistance to GLS, and over a period of years they had identified a number of inbred lines that produced resistant hybrids. In a diallel cross study combining reaction to MDMV and GLS, the same 14 "elite" inbred lines in the MDMV study and the same plots and plants were used for the GLS study. The lines were a mixture from corn belt and eastern states breeding programs. Virtually all lines contributing resistance originated in eastern states where disease pressure by GLS had facilitated selection. Only B68 was of Corn Belt origin; this line and NC250, Pa875, Va14, Va17, and Va85 were considered contributors of GLS resistance in the diallel study.
As previously stated, Donahue used the same plots in the MDMV study for a GLS study. He found as for MDMV, GLS resistance was highly heritable and controlled by additive genes. (It is difficult for me, the writer, to deduce how the effects of GLS and MDMV could be separated in this experiment.). The correlation coefficient for GLS and yield was r = +0.472. There should have been a high correlation coefficient for total disease and yield, but no such coefficient was calculated (Donahue, Stromberg, and S.L. Myers, Crop Sci. 31:926-931, 1991.).
Weed scientists made contributions to the control of maize virus diseases by quantifying the effect of post-emergence application of herbicides on severity of virus diseases. John W. Eberwine earned a Ph.D. degree while making such a study (J.W. Eberwine. 1996. Effect of postemergence johnsongrass control on MCDV and MDMV incidence and severity in field corn. Ph.D. Diss, V.P.I. & S.U.). In essence, herbicide-killed johnsongrass as it died became less palatable to aphids and leafhoppers causing them to move to corn. The effect was greater on MCDV than on MDMV because aphids were much more efficient in spreading MDMV and would spread the virus irrespective of herbicides. Leafhoppers, being much less numerous, tended to remain in place until disturbed or until host plants became unpalatable. Thus, MCDV was more severe after herbicide application than in untreated areas (Weed Tech. 12:121-127, 1998.).
Research on GLS resistance took a step into the molecular biology world when M.A. Saghai-Maroof (of the Department of Crop and Soil Environmental Sciences) and Stromberg and others collaborated to use RFLP analysis for 78 marker loci scattered through all 10 maize chromosomes. They studied F2 and F3 of the cross of B73 (susc.) X Va14 (res.). Quantitative trait loci conditioning resistance were found in chromosomes 1, 4, & 8 (large effects) and chromosome 2 (smaller effect). All resistance loci originated from Va14 (Theor. Appl. Genet. 93:539-546, 1996.). This was the first application of molecular procedures to disease-resistance studies at V.P.I. & S.U.
There is always in plant pathology a need to know the economic impact of a disease on a crop. Stromberg, M.R. Carter (a graduate student), and L.E. Flinchum (Research Supervisor) conducted a series of experiments to determine the effect of GLS on yield and other agronomic traits. They applied several different fungicides two or four times. In different treatments, yields were increased 24 to 69% by fungicides. It was shown that reduced number kernels per ear and reduced kernel weight were components most affected (Fungicide & Nematicide Tests 45:200, 46:241, 48:207, 53:143-144; Carter included these studies in her M.S. Thesis titled "Gray leaf spot of corn: Yield loss and evaluation of germplasm for resistance, 1992. 1990-1998). This was valuable information for convincing growers to plant the most resistant hybrids and convincing administrators or granting agencies to support research on GLS.
On December 1, 1987, Herman L. Warren, a U.S.D.A. corn pathologist on the Purdue University faculty, was appointed Commonwealth Visiting Professor in PPWS. During his year-long stay, he prepared publications on his research at Purdue. The work emphasized anthracnose (Colletotrichum graminicola) on corn and sorghum, gray leaf spot (GLS = Cercospora zeae-maydis) and southern leaf blight (Bipolaris maydis) of corn. Warren was courted for employment at V.P.I. & S.U. and on May 1, 1989 was appointed Professor of Plant Pathology. He was assigned 60% extension and 40% research time. During the Moore Era, his extension efforts were on vegetable crops (see section on vegetable pathology); his corn research was largely related to breeding germplasm for resistance to GLS and supervising three students through Ph.D. programs on corn diseases. Interestingly, the students researched three diverse problems.
Edvardo J. Traut, a native of Buenos Aires, Argentina, studied variation in Bipolaris zeicola and resistance to the fungus. With six inbred lines, Traut distinguished 11 races of B. zeicola. He pointed out that the three lines used in prior race determinations were too limiting as differentials. This is a reasonable conclusion since genes in corn conditioning reaction are known at two loci, Hm and Hm2 ; in addition, two alleles, HmA and HmB, may occur at the Hm locus. If the gene-for-gene hypothesis were invoked, several additional races should be recognized. B. zeicola, unlike other fungi, produces a toxin which changes the basic symptoms; the ability to produce or not to produce the toxin must be included in race determinations of B. zeicola (Traut, E. J., Ph.D. Diss., V.P.I. & S.U., 1993.).
Anne E. Dorrence studied the inheritance of resistance to diplodia ear rot and variability in Stenocarpella maydis through isozyme analysis (Dorrence, A. E., Ph.D. Diss., V.P.I. & S.U., 1995.). The fungus was formerly named Diplodia maydis and D. Zeae; hence, the disease is called diplodia ear rot. From a diallel study of nine inbred lines, she found general combining ability effects were significant, indicating that dominance or epistatic effects were important. Inbred lines B37, H111, B68, and M5 consistently contributed greatest resistance among the nine lines studied. In the isozyme study, 47 isolates were examined and isozyme polymorphisms occurred at a low level. This is more characteristic of biotrophs than of autotrophs such as S. maydis.
In 1998, Symon F. M. Mwangi completed a dissertation on maize diseases in Kenya. Most of the research was conducted during the Moore Era. He surveyed Kenyan maize fields and concluded diseases caused by Exserohilum turcicum, Phaeosphaeria maydis, Bipolaris maydis, Puccinia polysora, P. sorghi, and maize streak virus were the most common and most destructive Nineteen E. turcicum isolates from Kenya were classified into 5 races of the Leonard et al. scheme (Leonard, Levy, & Smith, Plant Dis. 79:776-777, 1989.), and 3 races which did not fit the Leonard et al. scheme (Mwangi, S. F.M., Ph.D. Diss., V.P.I. & S.U., 1998.).
Although not published until the Hatzios Era (1997 - 2000), a review article on GLS was prepared by J.M. Ward, South Africa; Stromberg; D.C. Nowell, South Africa; and F. W. Nutter, Jr., Iowa. The article, "Gray leaf spot, a disease of global importance in maize production" (Plant Dis. 83:884-895, 1999.), reviewed the history of GLS through 1998. Until the 1990-91 growing season in South Africa, GLS was only known from the western hemisphere, primarily the United States (Latterell and Rossi, Plant Dis. 67:842-847, 1983.). It caused economic losses in the 1990-91 growing season of South Africa; it now occurs destructively in most East African countries north to Ethiopia. Surprisingly, Mwangi did not detect it in Kenya. Both Stromberg and Warren have established research and consulting connections in Africa regarding GlS.
It is amazing that a disease that first sprang into prominence in Virginia in 1971 has become a damaging disease in the U.S. Corn Belt and much of Africa. Even though its presence in the U.S. was discovered in 1924, it was relatively unimportant until farmers adopted reduced tillage and continuous corn cropping systems with susceptible hybrids.
Small Grains - From 1948 to 1988, plant breeder T. M. Starling and plant pathologist C. W. Roane cooperated to breed disease-resistant small grain cultivars for Virginia and surrounding states. Their aim was to breed stiff-strawed, high-yielding, high quality, disease-resistant cultivars. They were joined in this endeavor by loyal, conscientious assistants, A. M. Price at Blacksburg and W. Sisson at Warsaw, both of the Agronomy Department and most recently, L. E. Flinchum of Plant Pathology, Physiology and Weed Science at Blacksburg. They were also assisted by several graduate students and agricultural technicians. They are indebted to H. M. Camper, Jr., Superintendent of the Eastern Virginia Research Station at Warsaw, who was greatly interested in cereal improvement and who provided land, labor, chemical, and machinery needs. Indeed, Camper was considered a co-developer of all released cultivars. Whereas the two departments bore most of the expense of the cereal improvement project, the program was enhanced by grant funds primarily from the Virginia Agricultural Foundation (later Va. Agri. Council).
Roane retired August 31, 1986 after 39 years and two months of service. However, he continued in emeritus status to be the plant pathologist cooperating with Starling until his retirement in December 31, 1988. Thereupon, C.A. Griffey took charge of the breeding program, sans cooperation of a plant pathologist. During the Starling-Roane era, 10 barley, 9 wheat, and 2 oat cultivars were released. Each possessed resistance to one or more diseases.
Barley diseases emphasized were leaf rust, powdery mildew, spot blotch-net blotch complex, scald and barley yellow dwarf.
Oat diseases emphasized were crown rust, stem rust, red leaf (= yellow dwarf), victoria blight, and soil-borne mosaic.
Wheat diseases emphasized were powdery mildew, leaf rust, stem rust, soil-borne virus diseases, and septoria leaf and glume blotch.
Stromberg took on programs designed to improve yield through management of diseases, but he did not participate in the breeding project. Thus, early in the Moore Era, small grain pathology underwent marked changes.
During the period 1984 -1988, when Starling retired and Roane stopped post-retirement work on the small grains project, two aspects of research were followed. The breeding program was continued (and handed over to C. A. Griffey in 1989) and special studies were carried out on virus-infested land (the W.D. Edwards farm near Lyells in Westmoreland Co.) to determine the mode of inheritance of reaction to wheat spindle streak mosaic virus (WSSMV) and to select breeding lines and cultivars resistant to WSSMV (Wheat Newsl. 35:197-199, 1989.). Although cultivars in drill-rows were readily classifiable as resistant (non-symptomatic) or susceptible (symptomatic), when space planted they behaved erratically. Because cultivars used as resistant parents in crosses were unstable, F1 and F2 data did not provide sensible hypotheses for number of genes conditioning reaction. It appeared that susceptibility was dominant. Data also suggested that selection for resistance could only be efficiently executed on infested soil.
In diseases incited by "soilborne" viruses wherein the virus survives in soil or on the vector, in this case, Polymyxa graminis, factors affecting the epidemiology of the vector must be considered. Conditions sometimes are not favorable for the fungus to vector the virus. In the 1984-85 and 1986-87 seasons, nurseries on infested soil were very useful for selecting resistant germplasm; the 1985-86 season was not (Roane & Starling, Reports to the Va. Agri. Council, 1985-1988.).
Assessing the effect of WSBMV and WSSMV on yield proved difficult. It was almost impossible to obtain side-by-side data from diseased and disease-free plots. The best that could be done was to compare yields from nurseries on virus infested and virus-free fields. In the Roane-Starling studies, yields at Lyelle and the research station were compared. There were indications that virus depressed yields of susceptible cultivars, but the data were not clearcut. High-yielding cultivars in virus-free nurseries tended to be high yielding on infested land, regardless of their reaction to virus. Studies on "soilborne" virus diseases proved to be both frustrating and intriguing.
The precise mechanism of vectoring by Polymyxa graminis of wheat viruses has not been understood. R. L. Grayson applied his expertise with the electron microscope to the problem. An anomaly emerged immediately. S.A. Tolin, departmental virologist and consequently an expert electron microscopist since the late 1960's, had only been able to find the long flexuous rods of WSSMV in wheat tissues. Grayson examined infected tissues of wheat from soils thought from symptoms in wheat to have WSBMV. Samples were obtained mostly from symptomatic wheat in Orange County, an area not sampled in Tolin's studies. Tolin verified that WSBMV was present in Grayson's samples. Although this was not the point of Grayson's studies, he had shown that the Orange area had WSBMV, and Tolin had shown that the Warsaw area had WSSMV.
Continuing with Grayson's objective to establish through electron microscopy the physical relationship between WSBMV and Polymyxa graminis, graduate student Mary Sue Mayes as Grayson's advisee selected the topic for her M.S. thesis. Mayes found that the fixatives then in use (glutaraldehyde or osmium oxide) caused WSSMV particles to deteriorate rapidly, whereas paraformaldehyde kept the particles intact. This revelation did not totally resolve the electron microscope studies of thin root sections for establishing the wheat-fungus-virus relationships. Mayes observed virus projecting from the surface of P. graminis but not attached parallel to the surface. No virus was observed within the fungus. Up to 15 virus particles were observed associated with cross-sections of the fungus, perpendicular to the surface of plasmodia. Since a section represents only a minute portion of a P. graminis plasmodium, it is difficult to estimate how many viruses might be attached to a single plasmodium. Mayes obtained evidence that the virus replicates in the fungus, and for this reason she thought the virus spreads rapidly through the host roots. It is then translocated and replicates in the foliage. Mayes never demonstrated that WSSMV survives dormant (summer) periods in cystosori and cysts. Even though she was the first to demonstrate clear-cut physical association between WSSMV and P. graminis, sad to say no journal publications were issued from her electron microscope work (Mary S. Mayes, 1989. An ultrastructural and immunocytochemical study of the wheat soil-borne mosaic virus/Polymyxa graminis relationship. M.S. Thesis. V.P.I. & S.U.). Two papers on the effects of chemical and physical environments on WSBMV were presented at American Phytopathology Society meetings (Phytopathology 79:1989; 81:1155, 1991.). Neither Grayson nor other students pursued the topic further.
As mentioned before, the small grains breeding program was under the leadership of C.A. Griffey beginning in the spring of 1989. Griffey mechanized the planting and harvesting procedures. For a while, he evaluated the germplasm that had been generated in the Starling-Roane era. In 1990, 'Wakefield' and 'Madison' were released; both were being tested for possible release beginning in 1986, three years before Griffey's appointment (Crop Sci. 31:1705; 1705-1706, 1991.). In the release notice, Wakefield was described as having the Pm1 gene for powdery mildew resistance, but as being susceptible to powdery mildew in Virginia; the Lr10 gene for leaf rust resistance; and Sr15 and possibly Sr10 for stem rust resistance. Madison was moderately resistant to powdery mildew; possessed Lr10 and Lr11 genes for leaf rust resistance and Sr6, Sr17, and Sr36 for stem rust resistance; was resistant to wheat spindle streak mosaic virus; and the Great Plains biotype of Hessian fly. Madison, incidentally, was named for Thomas Madison Starling; the name Starling was not available for wheat.
In 1990, there began a period when wheat lines were released to private seed companies. The disease reactions of these releases were not described in journals as were those of public releases. In the Moore Era, eleven private (or exclusive) and five public releases were made. Public cvs. in addition to those previously described were 'Jackson', 1993; 'Pocahontas', 1997; and 'Roane', 1999.
Jackson was released in June 1993 from a cross made by Starling in 1982 (Crop Sci. 36:1074-1975; 1996.). When released, it was moderately resistant to powdery mildew, carried Lr11 plus unidentified genes for leaf rust resistance but was only moderately resistant, was resistant to stem rust, moderately tolerant of septoria leaf blotch and glume blotch, and moderately susceptible to wheat spindle streak mosaic.
Pocahontas was released in February 1997 (Crop Sci. 41:1361-1362; 2001.). It was described as resistant to powdery mildew and several prevalent races of the stem rust fungus and moderately resistant to glume blotch. However, it was susceptible to leaf rust (Lr11 was not effective), moderately susceptible to barley yellow dwarf virus, and susceptible to wheat spindle streak mosaic virus.
Roane, although released in 1999, resulted from a cross made by Starling in 1984 (Crop Sci. 41:1359; 2001.). When released, Roane was resistant to barley yellow dwarf virus and powdery mildew; it probably possesses Pm4a and Pm3a. Adult plants are moderately resistant to leaf rust, septoria leaf blotch and glume blotch, and scab. It was susceptible to stem rust and both soil-borne virus diseases. Roane was the final publicly released wheat cv. originating from crosses made by Starling and tested and released by Griffey. Roane "was named in honor of Curtis W. Roane, Professor Emeritus....for his contributions toward the development of disease and insect resistant small grain cultivars."
Griffey also released four barley cvs. from crosses made by Starling; 'Callao', 'Nomini', 'Pamunkey', and 'Starling'. All have multiple disease resistances.
Nomini, released in 1992, resulted from a cross made by Starling in 1977 (Crop Sci. 34:300; 1994.). It was described as resistant to barley yellow dwarf virus, net and spot blotch, powdery mildew, scald, and septoria leaf blotch. It was susceptible to leaf rust.
Starling, released in 1993, resulted from a cross made by Starling in 1977 (Crop Sci. 36:1076-1077; 1996.). When released, it was resistant to barley yellow dwarf virus, net and spot blotch, scald and septoria leaf blotch; it was susceptible in seedling stages, but moderately resistant as adult plants to leaf rust and powdery mildew. Obviously, Starling was named in honor of Thomas M. Starling, Professor Emeritus, in recognition of contributions made to small grains breeding and genetics.
Callao, released in March 1994, resulted from a cross made by Starling in 1981 (Crop Sci. 36:1077; 1996.). When released, it was moderately resistant to powdery mildew, net blotch, scald, spot blotch, septoria leaf blotch, barley yellow dwarf virus, and leaf rust.
Pamunkey, released in 1997, resulted from a cross made by Starling in 1977. When released, Pamunkey was moderately resistant to barley yellow dwarf virus, net and spot blotch, powdery mildew, scald, and septoria leaf blotch, but susceptible to leaf rust.
In addition to leading the barley and wheat breeding programs, Griffey, with colleagues and graduate students, has actively investigated the inheritance of disease reactions and the impact of diseases on various cultivars. The genetic studies may be reviewed in more detail than is necessary for this history, but the author (Roane) also made contributions on these subjects and they still remain dear to his heart. Studies by Griffey et al. relative to wheat powdery mildew and barley leaf rust resistance are continuations of those initiated by Roane and Starling.
The terms "slow mildewing", "partial resistance", and "adult-plant resistance" had been utilized to describe resistance that did not seem to fit resistance conditioned by specific, generally dominant, major genes. Adult plant resistance (APR) apparently was first recognized in the U.S.A. by Shaner et al. at Purdue University in 'Knox' wheat (Phytopathology 63:867-872, 1307-1311; 1973.). In Virginia, APR had been recognized in the cv. 'Massy' as field resistance', which according to the release notice had no specific Pm genes (Crop Sci. 24:1000, 1984.). However, the term APR was first applied to Massey by Griffey, Das, and Stromberg (Plant Dis. 77:618-622; 1993.). They reported that in tests where fungicides were applied for powdery mildew control, compared to untreated plots, little or no grain yield was gained among cvs. having APR, i.e., 'Houser', 'Knox62', 'Massey', and 'Redcoat'; susceptible, unprotected 'Saluda' averaged a 13.4% loss. Griffey and M. K. Das studied the inheritance of APR in the cvs. Massey and Knox62 (Crop Sci. 34:641-646, 1994.) by both qualitative and quantitative means. The qualitative analysis indicated two recessive genes conditional APR in each cv. No Massey X Knox62 populations were examined. In the quantitative analysis, two or three genes were indicated to condition APR in each cvs. This time the study of Massey X Knox62 showed at least one gene in common since no susceptible segregates were observed.
Das and Griffey studied the heritability of powdery mildew in five cvs. with APR, including Virginia-bred Massey. They found general combining ability, GCA, to be more important than specific CA and that APR was quite heritable. All cvs. were promising sources of APR for breeding protection from powdery mildew induced losses (Das and Griffey, Phytopathology 84:406-409, 1994; Crop Sci. 34:948-952, 1994: Genome 38:277-282, 1995.).
The use of specific, major genes for powdery mildew resistance was very frustrating. Time after time, resistant cvs. were soon overcome by mildew races with matching virulence, yet interest and hope remained high that some Pm gene would be deployed that could stabilize resistance. For this reason, the research for new genes continued. When new sources of resistance were introduced, it was necessary to show that they carried new genes or alleles. Consequently, genetic studies were always under way. Y. S. Chung, under Griffey's guidance, conducted dissertation research on 10 winter wheat lines that had been previously studied in an M.S. project by Starling's advisee G. Jeyandran (M.S. thesis, V.P.I. & S.U., 1984.). Since Jeyandran's results produced questionable conclusions, Chung crossed the 10 lines with susceptible 'Chancellor' and with 13 powdery mildew differential lines, each of a different genotype. Although six genes were found among the 10 lines (Chung and Griffey, Crop Sci. 35:378-382, 383-388; 1995.) studied, none was new. Only two of the existing genes (Pm4a and Pm17) are individually effective against powdery mildew in southeastern U.S.A., but these had not been deployed by 1995. Should they be, mostly likely single mutations would provide virulence, and specific gene powdery mildew resistance would once again succumb. Thus, deployment of APR may be the more dependable route.
Griffey and his students took an interest in the genetics of barley leaf rust resistance. Except for 'James' (having Rph2 and possibly Rph6), all barley varieties released in Virginia possessed Rph7, a gene from 'Cebada Cepa' which provided leaf rust resistance for over 20 years. In 1990, virulence for Rph7 was detected in Puccinia hordei collections from Virginia, California, and Pennsylvania. Although virulence for Rph7 was known from Israel (1978) and Morocco (1981), until 1990 none had been detected in the Western Hemisphere (Steffenson, Jin, & Griffey, Plant Dis. 77:867-869, 1993.). Thus, all Virginia barley cvs became susceptible to leaf rust. Griffey et al. showed from tests with 21 entries at Painter in 1991 and 1992, and at Warsaw in 1992 that leaf rust caused a grain loss averaging 16% (Plant Dis. 78:256-260, 1993.). Brian Steffenson, Y. Jin, and Griffey observed that pathotypes virulent for Rph7 were avirulent for Rph3, -5, and -9. None of these genes have been deployed in North America. In regard to their future deployment, they warned, "The continued use of single Rph genes in barley cvs. will likely result in ephemeral resistance, because virulence for all described leaf rust resistance genes is known in the global population of P. hordei" (Plant Dis. 77:867-869, 1993.). The alternative seems to be in utilizing APR as shown to occur in Massey wheat, but has not been observed in Virginia-bred barley germplasm. Fungicides are available for controlling rusts, but their application to barley would not be economically feasible.
In the early 1980's there was a team effort to develop intensive management practices for small grains. Mark Alley and Dan Brann from Crop and Soil Environmental Sciences spearheaded the project. Breeders, soil and weed scientists, pathologists, entomologists, seed farm personnel, agricultural engineers, county agricultural agents, and several farmers cooperated. The information and prescribed practices from this project have resulted in an increase of wheat yields (state average from 42 to 68 bu/ac (nearly 65% increase) from circa 1985 to 1995. The increases were attributed to narrower drill-row spacing, higher rates of nitrogen application, better pest control, better cultivars, and stricter attention to rotation and planting dates. Plant pathologists Babineau (early in the program), Stromberg, and Baldwin contributed. They evaluated the effects of crop sanitation, rotations, planting date, balanced fertility, disease-free seed, resistant cultivars, and seed and foliar fungicides and insecticides on the severity of powdery mildew, leaf rust, leaf and glume blotch, tan spot, loose smut, head scab, barley yellow dwarf virus, wheat soil-borne viruses (WSBMV and WSSMV) and wheat streak mosaic. Although several journal papers were published on particular phases of the project, recommendations were published annually in the Pest Management Guide: Field Crops (Va. Coop. Ext. Publ. 456-016, rev. ann.). Detailed descriptions of circumstances and environments are given for control of barley yellow dwarf, and the foliar diseases powdery mildew, leaf rust, and leaf blotch. Resistances of cultivars and details for applying fungicides are tabulated. Both wheat and barley diseases are addressed. Most of the small gains section of the Guide was prepared by Stromberg. Much of his work is documented in the American Phytopathological Society annual publication Fungicide and Nematicide Tests vols. 40-52; 1986-1988.
With Stromberg evaluating seed treatment and foliar fungicides and Griffey turning out resistant cultivars, small grain farming should be economically sound well into the 21st century.
Saghai-Maroof also made contributions to barley genetics by making use of restriction fragment length polymorphisms (RFLP's). In cooperation with researchers at Washington State University (A. Killian and A. Kleinhofs) and North Dakota State University (B.J. Steffenson), results were obtained showing the gene for stem rust resistance, Rpg1, to be in the extreme subteleomeric region of chromosome 1P. A map of the region was provided (Molecular/Plant Microbe Interactions 7:298-301, 1993.).
With students R.M. Biyashev and Q. Zhang, Saghai-Maroof also made a study of a single qualitative gene for barley powdery mildew resistance, Mla12, and quantitative differences affecting mildew reactions. In their words, "Quantitative differences are likely to exist among alleles even at loci which are considered to carry major genes for resistance, and minor effects may be prevalent in cultivars that are not known to carry major genes for resistance" (Theor. Appl. Genet. 88:733-740, 1994.).
Stromberg took an interest in wheat take-all that became more prevalent about 1990 as a result of intensive management. Intensive management involved very high seeding and fertilizer rates, with nitrogen applications conducive to take-all. The problem was eventually addressed by two doctoral graduate students. Their research was reported in dissertations: James G. Crozier.1999. Evaluation of agents for suppression of take-all of wheat in Virginia in greenhouse and field studies and characterization of isolates of Gaeumannomyces graminis varieties. Ph.D. Diss. V.P.I. & S.U.
Sansanalak Rachdawong. 1999. PCR based test for differentiating Gaeumannomyces graminis varieties. Ph. D. Diss. V.P.I. & S.U.
From Crozier's work, only an abstract was published. This covered greenhouse work; using cone-shaped containers and soil infested with G. graminis var. tritici, Crozier suppressed take-all with NH4 fertilizer and enhanced it with NO3; Mn2+ did not suppress take-all. These findings merely agreed with previous determinations (Phytopathology 86:5124, 1996.).
Rachdawong developed a diagnostic test for G. g. avenae, G.g. graminis, and G.g. tritici which could be executed in a single polymersase chain reaction (PCR) tube. She further showed that ability to oxidize Mn from MnSO4. In general, G.g. tritici was a strong oxidizer, G.g. graminis was moderate, G.g. avenae was a non-oxidizer. However, the test was not as precise as the PCR procedure. Only an abstract was published (Phytopathology 86:S124, 1996.).
Two conspicuous changes involving trees occurred in the Twentieth Century; the chestnut trees were destroyed and Christmas trees became commonplace in our mountain landscapes. Early in the chestnut blight epiphytotic, many scientific man hours were devoted to stemming advance of the blight down the Appalachians, yet the chestnuts were destroyed. Efforts by pathologists and others subsided until about the 1970's when a cadre of curious scientists began to wonder if new discoveries and technologies might make it possible to reintroduce the chestnut into the forest canopy. Initially, the "restore the chestnut" pioneers in Virginia were John R. Elkins of Concord College, Athens, West Virginia, on educational leave working with R. J. Stipes. Soon, G. J. Griffin and Martha K. Roane were involved in different aspects of chestnut blight and their joint efforts culminated in an American Phytopathological Society Monograph "Chestnut Blight, Other Endothia Diseases, and the Genus Endothia" (1986). This publication summarized the literature on chestnut blight through early 1984. More will be said about the Monograph later.
Forest pathology at V.P.I. & S.U. came into being with the hiring of J. M. Skelly in the Couch Era. His primary interests were pine root diseases and air pollution effects on vegetation. When Skelly resigned, one of his proteges, S.A. Alexander, became forest pathologist and B. I. Chevone inherited the air pollution research. In 1991, Alexander was awarded a leave of absence to work on an Environmental Monitoring and Assessment Program for the Environmental Monitoring and Assessment Program for the Environmental Protection Agency. Upon returning in 1995, he was appointed to fill a vacancy at the Eastern Shore Agricultural Research and Extension Center. Thus, his career in forest pathology ended. During Alexander's leave period, Jodi A. Carlson, as Research Associate, Sr., assumed the duties of forest pathologist. When Carlson resigned in 1995, no forest pathologist was appointed. Griffin continued research on chestnut blight, and Stipes worked with tree diseases mostly in landscape situations. Several graduate students earned degrees by investigating tree diseases. Gradually, chestnut blight became the premier subject of forest pathology. It was also a primary topic for employees of the Virginia Division of Forestry headquartered in Charlottesville.
Up to the beginning of the Moore Era, Heterobasidion annosum root rot of pine trees had been emphasized by Skelly and then Alexander. However, during the Moore Era attention to this problem waned and was over-shadowed by emphasis on Verticicladiella proceera (later Leptographium procerum), the cause of a root disease of pine. Procerum root diseases, (PRD) as it came to be known, was very destructive to pine in Virginia's Christmas tree plantations; it became epidemic in 1990, causing a $6 million loss. This loss, plus the fact that Christmas tree plantations were more conveniently located to V.P.I. & S.U. than were forest seedling and tree plantations, contributed to waning interest in annosum root rot and intensification of study on PRD.
In the Moore Era under the direction of Alexander, one thesis and three dissertations were devoted to research on PRD:
Katherine J. Lewis. Studies on the spread of Verticicladiella procera by soil-borne and insect-borne propagules. M.S. Thesis, V.P.I. & S.U. 1985.
W. E. Horner. Etiologic studies of Verticicladiella procera Kendr. in pine Christmas trees. Ph.D. Diss. V.P.I. & S.U. 1985.
R.J.L. Nevill. The association of Leptographium procerum (Kendr.) Wing. by root feeding insects in Christmas tree plantations. Ph.D. Diss. V.P.I. & S.U. 1990.
Jodi A. Carlson. Procerum root disease physiology and disease interaction with ozone. Ph.D. Diss. V.P.I. & S.U. 1994.
With Alexander's transfer to Eastern Shore and Carlson's resignation, both in 1995, research on PRD ended. Lewis presented evidence that insect vectors (bark beetles and especially weevils) were the primary sources of effective inoculum for PRD. Soil contaminated with V. procera propagules was not a source of effective inoculum. Horner found the collar zone to be the initial point of colonization, the fungus "progressing acropetally in both directions" (? Meaning toward the shoot and root apices?). He also found the fungus could exist in resinous lesions for 22 months without inducing symptoms. Analysis of moisture content indicated the lesions induced stem drying, and as drying progressed foliar symptoms intensified. Nevill focused on weevils as vectors of the PRD fungus. Hylobius pales and Pissodes nemorensis were found to be the primary vectors and were nearly equally efficient. (Note: The name of the fungus had been changed in 1985 to Leptographium procerum.) Carlson prepared the final dissertation on PRD in the Moore Era. She undertook the examination of six physiological variables as they affected disease severity. The variables were pre-dawn water potential, change in pre-dawn to mid-day water potential, stomatal conductance, photosynthetic rate, transpiration rate, and exposure to ozone. The linear response to these variables was highly significant. From her long-time study of PRD, Carlson concluded that seedlings were infected, but trees did not become symptomatic for several years. Ozone injury occurring sometime after seedling infection may predispose trees to more rapid development of PRD and, consequently, a more rapid decline. Defense of Carlson's dissertation appears to have ended research of PRD at V.P.I. & S.U. in the Twentieth Century.
Before the book is closed on PRD, the results and usefulness of knowledge gained through the years needed to be transmitted to Christmas tree growers. Alexander's appointment as Extension Forest Pathologist necessitated that he carry out this function. He prepared a hand-out entitled, "Procerum Root Disease in Christmas Tree Plantations" (Undated but about 1992.). He described the symptoms and conditions favoring PRD, listed the suscepts of L. procerum, and made the following management recommendations:
- Plant trees on proper site for the species; avoid wet or dry sites.
- Remove pine slash from in and around the plantation.
- Keep weeds under control by mowing or with herbicides.
- Control weevils and bark beetles with insecticides. (Directions were given for stump and tree sprays and for plantations where PRD was either present or absent.)
In 1995, Alexander ended his leave as Technical Director of the Environmental Monitoring and Assessment Program for Forest Ecosystems, but instead of returning to Blacksburg he was appointed vegetable pathologist at the Eastern Shore Research and Extension Center in Painter. It is apparent but not stated that support for forest pathology in Virginia was withering. Although research on chestnut blight was increasing, internal support for it did not accrue. People dedicated to the belief that the chestnut could be restored to the forests fervently sought to sustain promising projects. Thus, some background information may be inserted on the discussion of chestnut blight research in the Moore Era.
Note: Much of the discussion on chestnut blight is condensed from the following publication: Martha K. Roane, Gary J. Griffin, and John Rush Elkins. Chestnut Blight, Other Endothia Diseases, and the Genus Endothia. Monograph Series, Amer. Phytopathol. Soc. Press. St. Paul, Minn. 1986.
Chapters and authors are:
Chestnut blight - G. J. Griffin and J. R. Elkins.
Other diseases caused by Endothia species - Martha. K. Roane.
Taxonomy of the genus Endothia - Martha K. Roane.
In the text, citations will appear as Monograph 1986.
There is an interesting anecdote regarding the approval of the monograph. I ( C. W. Roane) was chairman of the A.P.S. Monograph Committee at the time my colleague R .J. Stipes presented the proposal for it. Since my wife, Martha, would be an author, I had to be neutral in the discussion of the proposal and votes pertaining thereto. G. W. Bruehl, an A.P.S. past-president who commanded considerable respect and clout in society affairs, was vehemently opposed to approval. He summarized his arguments with, "Why beat a dead horse?" This was the prevailing attitude of those not familiar with the status of chestnut and chestnut blight research. I submit that the horse was merely 'playing possum'. Needless to say, publication was approved.
Interest in chestnut blight had its roots in R. J. Stipes' laboratory. The occurrence of pin oak blight (caused by Endothia gyrosa) resulted in two dissertations (P.P. Hunter, 1977; D. N. Appel, 1980.) on the effects of environment and stresses on the disease. Stipes invited J. R. Elkins, an organic chemist from Concord College, to spend his sabbatical leave investigating longevity in soil and movement in trees of methyl-2-benzimidozolecarbamate (MBC.)., the breakdown product of the systemic fungicide benomyl (Mono. 1986, p. 25.). Elkins was already a fervent believer that the chestnut could be restored, but he had no idea how it would come about. However, his avidness inspired Stipes, Griffin, and M.K. Roane to become involved in various aspects of chestnut research. Thus, Stipes began shifting his interest from E. gyrosa to the genus Endothia and E. parasitica in particular.
Several discoveries were prequisite to present-day approaches to blight control, the most notable of which was the discovery of hypovirulence in Endothia (now Cryphonectria) parasitica. In essence, hypovirulence is low virulence generally induced by cytoplasmically-borne dsRNA. The determinant is transmissible through hyphal anastomosis. The first discovery of hypovirulent E. parasitica was made in Italy. The value of hypovirulence as a biocontrol for E. parasitica was soon recognized and exploited. Hypovirulent cultures were first isolated in Virginia in 1977 and have been the subject of experiments by Griffin and his students ever since (Griffin et al. Proc. Amer. Phytopath. Soc. 4:108. 1977.).
Soon after hypovirulence was found in E. parasitica on large surviving chestnut trees (Castanea dentata), it was determined that those large trees possessed a low level of resistance to the fungus. This opened additional approaches to breeding blight resistant chestnut. Previous breeding schemes involved crossing C. dentata with oriental sources of resistance, C. crenata (Japanese) and C. mollissima (Chinese). There were some backcrosses to oriental trees but none to C. dentata (Monograph, 1986. pp. 19, 25.). Because Chinese X American crosses in F1 were intermediate in resistance, C. R. Burnham and P. A. Rutter concluded resistance was incompletely dominant. They also concluded that linkage between resistance and poor tree growth was unproven, because F2 populations demonstrating this hypothesis were non-existant (Mono. 1986. p.19.). Burnham proposed backcrossing American X Chinese F1 to American chestnut three times, then intercrossing the most resistant progeny to pool genes and bring resistance up to Chinese level. This will take years and Burnham who was 75 years old when he became involved with chestnut genetics and breeding was teased about his life-span optimism. His genetic and breeding proposals inspired an interested group to establish in 1983 the American Chestnut Foundation for raising money to support chestnut breeding. A farm was established in 1989 in Meadowview, Washington Co., Virginia to facilitate breeding. Fred Hebard, who had earned the Ph.D. degree under Griffin, was appointed scientist-superintendent.
I had taken Advanced Genetics and Cytogenetics from Burnham at the University of Minnesota in 1944-1946 and had used some of his translocation stocks to study linkage in barley. Through the years we had become good friends. In 1988, he prevailed on me to make some backcrosses on some F1 Chinese X American trees that were on the Horticulture Farm near Christiansburg (Trees are gone; Farm is a shopping area.). I used corn pollinating shoot and tassel bags to facilitate crosses. In 1988, I sent Burnham 56 nuts; in 1989, I sent Hebard 35 nuts of ( C A) A genotype. All were planted at Meadowview, but Hebard did not foresee impending disaster. Deer found the seedlings and only one escaped. He has since taken necessary measures to safe-guard seedlings.
Returning to the breeding schemes, the discovery of low level resistance opened two additional avenues of breeding. First, American chestnuts could be intercrossed to pool unlike genes and perhaps raise the resistance in purely American stock. Second, low level resistance could be crossed with stock carrying Chinese resistance, perhaps leading to superior resistance. Both of these schemes are being exploited (Griffin, Jour. Forestry 98 (2):22-27. 2000.).
It may appear from above that all the chestnut blight research in Virginia was centerd at V.P.I. & S.U. However, T. Dierauf and J. Artman of the Virginia Department of Forestry, Charlottesville, Virginia, have been involved at least since 1969. Under their leadership and in the cooperation with the Connecticut Agricultural Experiment Station, 12,000 seedlings of hybrid origin with American and Chinese or Japanese chestnut ancestry have been grown under exposure to wild E. parasitica at Lesesne State Forest in Nelson Co. One seedling in particular emerged with resistance and good form and it has been used in the backcrossing program (thus far to the BC2).
Experiments were started whereby scions from large surviving American chestnut trees were grafted onto American rootstocks in 1980. The plants were at Lesesne State Forest in an area surrounded by blight-infected stump sprouts. After 3 years, the scions had cankers of virulent E. parasitica and they were inoculated with hypovirulent strains. In 1996, these trees were 60 feet or more tall with 15-inch boles. Apparently, hypovirulence and low level of resistance combined to increase longevity of these specimens (Dierauf et al., Jour. Arboriculture 23:87-88, 1997; Griffin, Jour. Forestry 98(2):22-27, 2000.).
It had been determined that site conditions affected survivability of chestnut. High elevation, above 2500 feet, competition from other hardwood species, and xeric sites favored blight development even in hypovirulent-low resistance combinations. Thus, reforestation with chestnut is more apt to succeed in mesic, low elevation, low competition sites (Griffin et al. Canad. J. Pl. Pathology 15:159-167, 1993; Canad. J. Bot. 69:1804-1809, 1991.). Utilizing resistance, hypovirulence, and site management appear to favor success in re-introducing chestnut.
In the foregoing, much is written about hypovirulence, a complex biological phenomenon. There is much literature on developing understanding and utilizing it all over the world's chestnut habitat. Although Griffin, his students, colleagues, and even his wife, Lucille, have been major contributors, only a small fraction of the total effort is expended in Virginia. Yet, some of the most important contributions have been made here. Student projects have addressed hypovirulence by finding, isolating, cultivating, characterizing cultures, evaluating effectiveness in the forest, and many other aspects of a complex biosystem. Students and their theses/dissertations are listed here. To establish continuity, those before and during the Moore Era are listed chronologically:
Wendt, R.W. 1981. Presence of hypovirulent Endothia parasitica (Murr.) P. J. & H. W. Anderson in the general population of American chestnut, Cartanea dentata (Marsh.) Borkh.,. stump sprouts. M.S. Thesis, V.P.I. & S.U.
Hebard, F.V. 1982. Biology of virulent and hypovirulent Endothia parasitica on American chestnut (Castanea dentata). Ph.D. Diss. V.P.I. & S.U.
Micales, Jessie Ann. 1985. The chemotaxonomy of the fungal genus Endothia Fr. Ph.D. Diss. V.P.I. & S.U.
Frias, Graciella M. 1992. Roles of tannase and hydrolyzable tannins in chestnut blight. Ph.D. Diss. V.P.I. & S.U.
Robbins, Nancy E. 1997. Spread of hypovirulent strains of Cryphonectria parasitica among American chestnut trees at Lesesne State Forest. M.S. Thesis. V.P.I. & S.U.
Some of the contributions by the authors listed above are discussed below.
Micales gave a thorough review of the taxonomy of Endothia. The integrity of the genus had been questioned in 1978 when Margaret E. Barr published a paper entitled, "The Diaporthales of North America with emphasis on Gnomonia and its segregates" (Mycologia Mem. 7. J. Cramer, Lehre, Germany, 1978. 232 pp.). She retained in Endothia those fungi having, "Brightly colored, pseudo-parenchymatous stromata, a diatrypoid configuration and one-celled, allantoid ascospores..... The majority of the fungi that were traditionally included in Endothia were transferred to the genus Cryphonectria Sacc. of the family Valsaceae. These fungi are distinguished by prosenchymatous stromata, a valsoid configuration and two-celled, ellipsoid or ovoid ascospores" (Micales, 1985, p. 8.). Micales examined the morphology of 12 species assigned to Endothia before 1978, and "Applied polyacrylamide gel electro-phoresis and fungicide sensitivity assays to establish additional biochemical relationships among," the fungi. She concluded that, "Barr's classification system is technically correct. ..... Its adoption is recommended with some hesitation since the influence of host on stromal development is not fully understood" (Micales 1985, p. 9.).
Martha Roane, on the other hand, because of long-time use of E. parasitica attempted to have E. parasitica retained under nomen conservandum of the International Rules of Botanical Nomenclature. She ignored Micales results with chemotaxonomy, but stressed that prosenchymatous stroma could be compressed into pseudoparenchymatous stroma as stroma aged. She illustrated this hypothesis in an effort to refute Barr's classification scheme (Mono., 1986, pp. 31-33.). She ignored Micale's dissertation which supported Barr in favor of questioning the conclusiveness of the morphologic evidence which might have conserved the name Endothia parasitica. (I always thought her reason was sentimental rather than scientific; quite uncharacteristic of Martha Roane. - CWR).
In her study of tannase and tannins, Farias found E. parasitica tannase activity greater in American than in Chinese extracts. "Differences in tannase activity....may be used as a tool to identify sources of resistance" (Farias, Ph.D. Diss. 1992.).
Robbins assayed the spread of hypovirulent strains of E. parasitica (Cryphonectria parasitica) in inoculated trees and from such trees to stump sprouts in the surrounding forest. Limited spread occurred within inoculated trees but no spread from these to stump sprouts was detected (Robbins, M.S. thesis, V.P.I. & S.U. 1997.). Use of hypovirulent strains seems limited because no efficient means of dissemination has been developed.
In 1984, a group interested in restoring the American chestnut organized The American Chestnut Cooperator's Foundation (ACCF), a non-profit scientific and educational foundation; ACCF is attempting to restore American chestnut by interbreeding trees of low resistance to accumulate genes, by cloning resistant scions on existing sprouts, and by selecting and managing sites optimum for growth. The ACCF directors are G. J. and Lucille Griffin and J. R. Elkins. They solicit funds used strictly to fulfill the objectives; no salaries are involved. It is a noble effort. Would that the ACCF should succeed.
Other aspects of tree diseases are included in sections on air pollution, ornamentals, and new diseases.
Note: White pine blister rust was not mentioned in previous Eras because I could find no literature on it for Virginia. Early in 2002, Mr. Kenny May of the U.S. Forest Service, Edinburg, Virginia, provided me with a history white pine blister rust control in the U.S. The comments below are prompted by this material. I am grateful to Mr. May for his interest and help. -- C. W. Roane
White pine blister rust was probably present in North America in 1898, but its discovery in a nursery at Geneva, N.Y. in 1906 stirred interest. (W. V. Benedict. 1981. History of white pine blister rust control - A personal account. U.S.D.A. Forest Service. Wash., D.C.). Cronartium ribicola is a heteroecius rust of 5-needled pines (spermagonial and aecial stages) and Ribes spp. (uredinial and telial stages). In Virginia, R. cynosbati (prickly gooseberry), and R. americanum (wild black current), coincide commonly with the range of Pinus strobus, eastern white pine. White pine blister rust (WPBR) was perceived to be a threat to our forests. It precipitated the first federal plant quarantine in 1912. An Office of Blister Rust Control was established some time after 1915. Five regions for WPBR were established . Virginia was in the Southern Appalachian Region (with Ga., Ky., S.C., N.C., Md., Del, Tenn., and W.Va. The regional administrative office was in Richmond, Va., from 1931 to 1938 and in Harrisonburg, thereafter. The records are skimpy as to who was in charge, but it is believed that H. E. Yost served from 1938 to 1953 when the office was closed and Yost retired; afterward WPBR control was probably administered from Edinburg, Virginia.
From a paper prepared by C. E. Cordell, U.S. Forest Service, Ashville, N.C. (An evaluation of white pine blister rust in the George Washington National Forest, Virginia. Rept. 68:1-29, June 1968), the following facts have been gleaned:
Ribes eradication was conducted in Virginia for about 40 years (up to 1968).
The highest incidence of WPBR occurred in Highland Co.
It was assumed that Ribes eradication had effectively confined WPBR to that area.
Future eradication work should cease for 10 years (= 1977).
Surveys afterward should be based upon pine infection data instead of Ribes occurrence.
Infection centers should be under surveillance and no further action should be taken unless disease activity warrants it.
This is a quiet little corner in the history of plant pathology in Virginia. So far as I know, barberry eradication and WPBR control are the only federal plant pathology activities conducted in the State.
Originally, the Virginia Truck Experiment Station (VTES) was established in Princess Anne Co., near Little Creek, to study diseases plaguing producers of crops for the fresh market. Most products were sold to wholesalers in Norfolk, but a considerable volume was shipped to Baltimore, Washington, Philadelphia, and New York. The production area was concentrated in Norfolk Co. (now Chesapeake), Princess Anne Co. (now Virginia Beach), and the Eastern Shore counties of Accomack and Northampton. Gradually, as Chesapeake and Virginia Beach became almost totally urbanized, vegetable production was concentrated on Eastern Shore, and VTES became an ornamentals crop research and extension center serving nurserymen and home gardeners. Its name change reflected its subject matter, Virginia Truck and Ornamentals Experiment Station. For many years the center at Painter in Accomack Co. was a substation of VTES, but as it became almost the sole center for vegetable crop research it was made independent of the Virginia Beach center and both locations were renamed, e.i., Hampton Roads Agricultural Research and Education Center (HRAREC) and Eastern Shore AREC. Both were incorporated into the Virginia Agricultural Experiment Station and Extension Service. A plant pathologist had been assigned to each location, but when the Moore Era began there was no plant pathologist at HRAREC; R.E. Baldwin was at ESAREC. There would be no pathologist at HRAREC until Chuanxue Hong was appointed Assistant Professor in 1999.
During the Moore Era, R.E. Baldwin retired from the ESAREC on December 31, 1995. In anticipation of this, S.A. Alexander was moved from Blacksburg to Painter on August 1, 1995 and became solely responsible for vegetable pathology research and extension on January 1,1996. While not meaning to disparage Alexander, it did not seem to be a wise administrative decision to appoint a career forest pathologist to such a responsible vegetable pathology position.
Although vegetable pathology research and extension had by tradition been centered at Virginia Beach and Painter, R. C. Lambe, G. H. Lacy, and H. L. Warren at Blacksburg devoted some time to vegetable pathology, Lacy primarily in vegetable bacteriological research, Warren and Lambe in vegetable pathology extension. The role of each at Blacksburg and Painter and their contributions will be reviewed below.
Baldwin was the principal researcher in vegetable pathology. He repetitiously tested new products for disease control on the leading crops of Eastern Shore. Most of his research is reported in Fungicide and Nematicide Tests. Attention was given to fruit and foliage diseases of tomato, cucumber, squash, snap beans and strawberry and to potato foliage, seed piece, and nematode diseases. Usually, a companion publication in lay-language appeared in the Vegetable Growers News, a publication of the ESAREC. Annually, these published results were incorporated into recommendations to growers and were summarized in a series of pest management guides (Pest Management Guide for - Home Vegetable Gardens, VPI. & SU Pub. 456-002 (revised annually); - for Home Grounds and Animals, Section 2, Home Vegetables, V.P.I. & S.U. Pub. 456-018.). There were also pest management guides for home ornamentals, 456-019, nursery ornamentals, 456-010, (also numbered 456-070.), and horticultural and forest crops, 456-017. Baldwin collaborated with R. C. Lambe in publishing most of these pest management guides until Lambe retired in 1988, thereafter he soloed their preparation until he also retired in 1995. Afterward, it was Alexander's responsibility to continue the vegetable pathology in these publications.
Although the aim of field stations is to serve the commodity group of the area, and as a consequence the research is very applied, occasional original experiments are conducted. A series of studies with marigold were initiated when the poultry processing industry sought ways to improve the buyer appeal of chickens by adding xanthophyll to their rations. This would change skin color from white to yellow. The source of the pigment was marigold flowers. Lambe and Baldwin collaborated to develop production procedures. In doing so, they found that a marigold-white potato rotation enhanced potato production by reducing lesion nematode injury to potato roots. Alexander continued this work and reported increased yields of potato and tomato and concurrent reduction of lesion nematodes of African marigolds (Tagetes erecta) were used as a green manure crop (Biol. & Cult. Tests for Control of Pl. Dis. 11:95, 1996; 12:104, 1997.). There was no indication that marigolds were used in commercial potato and tomato rotations by the end of the Moore Era.
Herman Warren was a corn pathologist who was appointed Professor of Plant Pathology on May 1, 1989. Since he had been a federal employee at Purdue University, he wanted an appointment that would continue his federal retirement program. As Lambe had retired, it was arranged that he would be a part-time Extension Specialist in vegetable pathology. As such, he stressed a search of sweet corn, tomato, crucifer and cucurbit hybrids and cultivars for resistance to common diseases plaguing Virginia growers. The aim was integrated pest management of chemical and disease resistance in order to reduce chemical usage. His results were incorporated into various pest management guides. In essence, this was the type of Extension activity conducted by his predecessor, Lambe.
George Lacy, his colleagues, and graduate students made genetic modifications of the soft rot bacterium, Erwinia carotovora, such that modified strains were less virulent than wildtypes. Although the accomplishments were of high caliber, they have not yet been applied in agriculture.
Theses related to vegetable pathology:
D. P. Roberts. - Molecular mechanisms of pathogenesis incited by Erwinia carotovora subsp. carotovora. Ph.D., 1985. Lacy, advisor.
Caitilyn Allen. - Evolution of a gene for pathogenicity: Endopectate lyase. Ph.D., 1987. Lacy, advisor.
Sirkka R.M. Kyostio. - Erwinia carotovora extracellular proteases: Characterization and role in soft rot. Ph.D., 1990. Lacy, advisor.
Zenbiao Yang. - Gene regulation in a pathogen-plant interaction: Erwinia versus potato tubers. Ph.D., 1991. Lacy, advisor.
These theses would best be discussed in a section on molecular biology in plant pathology (not covered in this history).
Included in this section are the usual decorative plant species plus trees used in landscape situations. Faculty who held assignments in extension, instruction, and research on ornamental plant diseases were Robert C. Lambe who served nurserymen and home gardeners, Wirt H. Wills who studied diseases of shrubs, and R. J. Stipes who worked with trees. During the Moore Era, Lambe took a leave in Mexico and graduate student Melinda Mulesky Gates was acting vegetable and ornamental crop pathologist, May 1976 to February 1987. Lambe retired on May 31, 1988 and Wills on September 30, 1990. Mary Ann Hansen, the Plant Clinician, also rendered considerable service to nurserymen and home gardeners. The retirements of Lambe and Wills brought to a virtual stop at Blacksburg the research on ornamental plants and shrubs. The work of Stipes with landscape trees has been continued, and ornamentals pathology was moved to the Hampton Roads Agricultural Research and Education Center in Virginia Beach.
During the Moore Era, retirements, position freezes, and changing commodity emphasis caused reapportionment of Stipes time on three different occasions. From 1984 to 1989, his teaching, research and extension assignment was 10, 75, 25. For 1989 to 1995, it was 25, 65, 10; for 1996, it was 30, 10, 60; and in 1997, it was 30, 0, 70. Note that research time steadily declined and extension time steadily increased. Strangely, although his primary assignment addressed landscape trees, most of his research publications were on peanut diseases. This is because he was co-chairman of student committees with Phipps, and both chairmen were accorded authorship when students published results from their dissertation research on peanut. It is apparent that Stipes functioned excellently as the on-campus chairman; it is also apparent that in doing so, his attention to landscape research may have suffered. Nevertheless, he pursued several objectives to significant results.
Stipes worked avidly to develop injection procedures and chemicals for control of Dutch elm disease and other wilts of trees. His research helped to bring about the labelling of Arbotect 20S and Alamo for use in chemotherapy of tree diseases. These are approved for control of Dutch elm disease and are being tested by Stipes for control of dogwood anthracnose.
The nature of Stipes' research and extension projects can be rendered by noting the titles of some of his talks:
"Some famous patients I have known." Delivered to several audiences.
"Trojan horses in Appalachian forests."
Chestnut blight, Dutch elm disease, dogwood anthracnose; Appalachian Biogeography Symposium, et al.
"Managing plant diseases around the home."
"Basics in biology and stresses of the landscape tree." - Master Gardeners' Training.
"Tree crisis on the horizon." Va. Tech Horticulture Club.
"Diagnostic methodologies in tree diseases." St. Louis, Mo., Urban Tree Conf.
"Tree tips on tree troubles." Roanoke City Extension Services.
"What's hot in tree troubles."
"Update on tree injection technology and injectables." Pesticide Applicators Training Session.
"Pines pining away." Tidewater Horticulture Conference.
"Use of Alamo in the management of Dutch elm disease." Arlington National Cemetary.
Stipes' topics were technical, educational, and usually entertaining. His audiences ranged from college students to kindergarten kids, from professional horticulturists to amateur gardeners and putterers. He could teach to the level of each. The technical aspects are boiled down in extension guide books for public utilization, for example. The Pest Management Guide for Home Grounds and Animals, Virginia Cooperative Extension Publ. 456-016 (revised annually), wherein management of diseases of the most commonly grown landscape trees is discussed. New technologies are introduced as soon as they become available. Much of the information on ornamental shrubs contained in Ext. Publ. 456-016 was developed by R. C. Lambe and W. H. Wills. Both worked on shrubby ornamentals early in the Moore Era (Rhododendron, azalea, boxwood, Japanese holly, Photinia, and Leucothoe.). Later, toward their retirements they emphasized fungicidal control of vegetable diseases. A significant contribution to ornamental plant pathology was a chapter on azalea diseases in a book on azaleas (R. C. Lambe, W. H. Wills, R. K. Jones, and D .M. Benson. 1985. Azalea diseases. Pp. 359-373. In = Azaleas. F.C. Galle, ed., Timber Press, Portland, Oreg. 486 pp.) The book predated the Compendium of Rhododendron and Azalea Diseases described below by one year.
Martha K. Roane had been inoculated with an interest in Ericaceous plants when during her graduate study years she took a special course in taxonomy. She was inspired to prepare a volume in the APS Press compendium series on her favorite topic, Rhododendron. Somehow, she established contact with Duane L. Coyier of the U.S.D.A. Horticultural Crops Research Laboratory at Oregon State University, Corvallis, Oregon. Martha and Duane organized a group of 17 authors to prepare the text. APS Press requires that a publishing fund be raised to defray the cost of publishing its compendia. Several organizations became financial sponsors and publication was assured. The sponsors were:
Amer. Rhododendron Soc., Middle Atlantic Chapter.
Amer. Rhod. Soc. Portland Chapter.
Amer. Rhod. Soc. Research Foundation.
Drs. Kenneth and Sandra MacDonald.
Oregon Association of Nurserymen.
University Faculty Book Publishing Comm., VPI&SU
Virginia Nurserymen's Association, Inc.
It can be seen that several Virginia-based organizations were involved. The Compendium of Rhododendron and Azalea Diseases was issued in 1986. Martha's photographs adorned the covers. Of the 19 contributing authors, four were connected with our department:
Author Topic Maynard G. Hale Mineral Nutrient Deficiencies and Toxicities, pp.46-48. Laurence D. Moore Air Pollution Injury, 00. 48-50.
Pesticide Phytotoxicities, pp. 50-51.
G. Myron Shear Moisture Stress, Head Injury and Winter Injury, pp.45-46. Martha K. Roane Introduction, p. 1.
Rusts, pp. 26-28.
Aid to Diagnosis, p. 53.
In addition, a Ph.D. alumnus of the Department contributed two sections:
Ronald K. Jones Botryosphaeria Dieback, pp. 10-11.
Rhizoctonia Web Blight, pp. 20-21.
Martha also prepared the index, which reminds me of an old adage: "Any fool can write a book; it takes a genius to make a good index!"
After the Compendium was published, Martha collaborated with Molly N. Cline of the Monsanto Corporation, St. Louis, Missouri, to assemble an APS Slide Set of 87 slides on Rhododendron and Azalea Diseases. No doubt Martha prevailed upon persons she had contacted while preparing the Compendium to contribute slides.
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