Progress 10/01/02 to 09/30/07
Outputs
During the five-year life of the project, knowledge concerning the nature and control of several onion diseases of economic importance in New York was successfully developed and/or extended thereby justifying the goals and objectives of the project. Soil populations of Burkholderia cepacia causing the bacterial canker-sour skin disease were reduced by crop rotation practices in both laboratory and field experiments. The field experiments were conducted cooperatively with a Cornell Cooperative Extension Educator (John Mishanec) and several New York onion growers. During 2006 a bacterial disease of onions new to New York occurred in Orange County. The disease was characterized by a distinct discoloration and scale pattern in the tissues of infected onion bulbs. The bulbs remained firm and were not soft to touch by hand. Such infected bulbs generally were impossible to detect on commercial grading lines and when packed caused shipments to be refused at the market because
of the defect (disease) detected when the onions were inspected. Research conducted during 2007 in cooperation with researchers in Georgia has indicated the disease most likely was caused by Pantoea ananatis which previously had not been detected in New York. Conidia of Aspergillus niger cultures, transformed with a green fluorescent protein when inoculated either onto onion seed and/or amended into soil in which clean onion seed was planted, infected the resulting seedlings. Subsequently, the transformed bacteria were reisolated from the onion plants at different stages in their growth. Populations of A. niger were found to be much higher in soils cropped to onion in the generally higher temperature soils in Orange County than those in Oswego County with generally lower temperatures. In cooperation with Dr. Martha Mutschler, the Cornell onion breeding program has continued to transfer the strong Botrytis leaf blight (BLB) resistant gene(s) from Allium roylei to A. cepa. Two BC2 F3
populations are now fixed for BLB resistance. Several new fungicides were identified in field experiments for managing onion leaf diseases. Control of onion smut was achieved by seed treatment with the fungicide Raxil in cooperation with Dr. M. R. McDonald in Canada, Dr. A. G. Taylor at Geneva, New York, and several Cornell Cooperative Extension Educators in central and western New York. An economically severe occurrence of Botrytis neck rot of onion caused by Botrytis allii occurred in western New York during the winter storage season of 2000-01. Studies begun in 2003 in cooperation with Cornell Cooperative Extension Educator, Christine Hoepting, and continued annually since then, have revealed that bare root onion transplants imported from out of state locations frequently are infected latently with the pathogen. Such infected transplants lead to Botrytis neck rot of onion bulbs in storage. They also can be the source of inoculum during the same cropping year for infection of onion
seedlings and plants grown from healthy seed which can result in Botrytis neck rot in the subsequently formed onion bulbs.
Impacts
The research conducted has developed new approaches and identified materials for control of onion diseases commercially important in New York. Specific rotation crops now have been identified that will reduce the soil population levels of Burkholderia cepacia in New York muckland soils, thereby providing onion growers in the state with cropping choices to reduce the potential for outbreaks of the bacterial canker-sour skin disease it causes. The bacterium Pantoea ananatis, cause of center rot of onions, was detected during 2006-07 for the first time in New York. Cooperative efforts with researchers in Georgia resulted in identifying the bacterium by using molecular primers they provided. Continued cooperative research on the pathogen and disease should provide the knowledge needed to develop effective control procedures for center rot. The role of Aspergillus niger as a seedborne and latent pathogen in onions causing black mold is now better understood by utilizing
cultures of the fungus transposed with a green fluorescent protein in seed and soil inoculation experiments. Commercial onion seed companies will need to develop seed treatments for control of A. niger as a seedborne pathogen. Soils in Orange and Oswego Counties were found to have greatly different levels of A. niger. This explains one reason why black mold occurs more frequently and at higher levels in Orange County than in Oswego County. Growers will need to use cultural programs to control the disease until commercial seed treatments are available to protect seedlings from infection by soilborne as well as seedborne A. niger. Several new fungicides identified as effective in controlling onion leaf diseases in the field experiments conducted are now registered for use in New York and can be utilized in combination with traditional fungicides. They will be available as substitutes for traditional fungicides when their registrations are cancelled because of environmental or other
concerns. Resistant varieties for control of Botrytis leaf blight should soon be available obviating the need for fungicidal control. Commercial plant breeders who request the resistant germplasm should have the material available in the near future. Cooperative research has been initiated to prevent infection of onion transplants by Botrytis allii. The cooperative effort by Cornell Cooperative Extension Educators, Dr. M. R. McDonald in Canada, Dr, A. G. Taylor at Geneva, and several New York onion growers led to successful experimental control of onion smut by seed treatment with Raxil. This Hatch project was augmented by financial support provided by the New York Onion Research and Development Program (administered by New York Ag and Markets), the Cornell IPM Program, and Agribusiness Companies. New York onion growers provided land and crops for conducting portions of the research. The Orange County Vegetable Improvement Association provided a research facility for conduct of
specific aspects of the research. Without the cooperative efforts by others as noted, and the supplemental financial support provided, the successful outcome of the project could not have been accomplished.
Publications
- Haudenshield, J. S., and Lorbeer, J. W. 2004. Analysis of cover crop rotations influencing soilborne population levels of Burkholderia cepacia. pp. 55-58. In: Proceedings of the 2004 Empire State Fruit and Vegetable Expo - Proceedings Two, Syracuse, New York. 109 pp.
- Haudenshield, J. S., Lorbeer, J. W., Gundersheim, N. A., and Mark, G. L. 2004. Ecological dynamics of Burkholderia cepacia causing canker-sour skin of onions and integrated pest management approaches leading to control of the disease. pp. 139-147. In: Proceedings of 2004 National Allium Research Conference, Grand Junction, Colorado. 250 pp.
- Lorbeer, J. W., Seyb, A. M., de Boer, M., and van den Ende, J. E. 2004. Botrytis species on bulb crops. pp. 273-294. In: Botrytis: Biology, Pathology, and Control. Y. Elad, B. Williamson, P. Tudzynski, and N. Delen, eds. Kluwer Academic Publishers, Dordrecht, The Netherlands. 428 pp.
- Lorbeer, J. W., Haudenshield, J. S., and Tuffley, J. W. 2003. Nature and management of bacterial canker-sour skin, black mold, smut, leaf blight, and seedborne diseases of onion pp. 162-166. In: Proceedings of 2003 New York State Vegetable Conference, Syracuse, New York. 232 pp.
- Lorbeer, J. W., and Loparco, D. P. 2007. The versatility of Botrytis allii causing Botrytis neck rot of onions. pp. 144-146. In: Proceedings of 2007 Empire State Fruit and Vegetable Expo and Becker Forum, Syracuse, New York. February 13-15, 2007. 207 pp.
- Hoepting, C. A., and Lorbeer, J. W. 2007. Detection of systemic and latent presence of Botrytis allii in onion transplants. pp. 54-61. In 2006 New York State Vegetable IPM Project Reports. NYS IPM Publication Number 131. 143 pp.
- Taylor, A. G., Hoepting, C. A., Nault, B. A., Lorbeer, J. W., and McDonald, M. R. 2007. Onion seed treatment and coating technologies. Acta Horticulturae: In Press.
- Mutschler, M., Goldschmied, P., Loparco, D., and Lorbeer, J. 2006. Botrytis leaf blight onion selections have improved fecundity and are nearing commercial availability. pp. 147-149. In: Proceedings of 2006 Empire State Fruit and Vegetable Expo, Syracuse, New York. February 13-16, 2006. 193 pp.
- Seyb, A., and Lorbeer, J. W. 2006. Soilborne Aspergillus niger propagules as a source for onion seeding infection. Phytopathology 96(6)S-106.
- Seyb, A. M., and Lorbeer, J. W. 2006. Population levels of Aspergillus niger in muck soil in relation to the inoculum load required for infection of onion seedlings. Phytopathology 96(6)S-182.
- Seyb, A. M., and Lorbeer, J. W. 2005. Identifying the inoculum potential in New York organic soils of Aspergillus niger pathogenic to onion. pp. 111-114. In: Proceedings of 2005 Empire Fruit and Vegetable Expo and Produce Marketing Conference, Syracuse, New York. February 14-17, 2005. 188 pp.
- Seyb, A. M., LoParco, D. P., and Lorbeer, J. W. 2004. Infection of onion seedlings by soilborne inoculum of Aspergillus niger expressing green fluorescent protein. Phytopathology 94:594. Publication No. P-2004-0643-AMA. American Phytopathological Society.
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Progress 01/01/06 to 12/31/06
Outputs
(1) Muckland soils cropped to onions during 2006 in Orange County and Oswego County for population levels of Aspergillus niger (cause of black mold) indicated considerably higher levels of the fungus in the Orange County soils than in the Oswego County soils. Outbreaks of black mold continued to occur in Orange County, but were rare in Oswego County, indicating the potential annual occurrence of black mold in Orange County which has the warmer average temperatures of the two counties. Onion growers in Orange County now are advised to harvest onions during the cooler temperatures of the day and maintain good airflow through freshly harvested onions in the field and indoor storages. (2) Pristine, used alone or in combination with other fungicides in several field trials in western New York, indicated control of Botrytis leaf blight under light disease pressure from the pathogen, Botrytis squamosa. (3) The cooperative effort with Cornell plant breeders in developing
onion germ plasm resistant to Botrytis leaf blight from an Allium roylei source continued successfully during 2006. Several backcross generations have been completed and the progeny continue to indicate strong resistance to infection by Botrytis squamosa utilizing mist chamber and controlled field screens. The most recent backcross generation of the crosses has produced onion plants yielding normal and large sized bulbs. (4) Artificial inoculation of onion seed with Botrytis allii continued to result in systemic infection of onion seedlings by the pathogen. Placement of the systemically infected seedlings in a mist chamber at 68 F for 5 days with continuous leaf wetness resulted in sporulation of B. allii on the cotyledons and first leaves of the seedlings, but the results were inconsistent compared to those achieved during 2005. (5) High levels of B. allii infection of bare-root onion transplants were detected in a number of shipments of the transplants into New York from out of
state sources. In 50 entries during 2006, 79.3 percent of the bare-root transplants had some level of latent B. allii compared to 0 percent for plug transplants grown in New York and 0 percent for direct seeded seedlings. The study was conducted cooperatively with Christine Hoepting of Cornell Cooperative Extension in western New York.
Impacts
During 2006, research on black mold caused by Aspergillus niger continued to indicate the importance of seed- and soilborne inoculum of the pathogen in the occurrence of the disease in New York. After undercutting and field drying, the two cultural techniques: (1) harvesting onions during the cooler periods of each day and (2) the maintenance of good airflow through onion bulbs in field and indoor storage, will be emphasized to New York growers, particularly those in Orange County where the warmest weather in the onion growing areas of the state occurs and where soil levels of the pathogen are the highest. Fungicide seed treatments are needed to minimize the role of seed transmission of A. niger into New York onion cropping systems. Studies on fungicidal control of Botrytis leaf blight (BLB) during 2006 indicated that Pristine will control BLB and can be added to the group of fungicides that New York growers have available to combat the disease. The breeding program
to control BLB has now produced good-sized advanced generation backcrosses highly resistant to BLB. Studies during 2006 again proved the role of transplant onion seedlings in introducing Botrytis allii (cause of Botrytis neck rot) into New York onion cropping systems. Programs to eliminate this source of the pathogen are being designed for application in transplant production fields. Plug transplants produced in New York were shown to be free of the pathogen and are an alternative to transplants produced elsewhere.
Publications
- Hoepting, C.A., K.E. Panek and J.W. Lorbeer. 2006. Detection and management of latent Botrytis allii in onion transplant seedlings in New York. pp. 50-62. In: Proceedings of 2006 National Allium Research Conference, College Station, Texas. December 7-8, 2006. 140 pp.
- Lorbeer, J.W. and D.P. Lo Parco. 2006. The versatility of Botrytis allii as an onion pathogen. pp. 13-14. In: Proceedings of 2006 National Allium Research Conference, College Station, Texas. December 7-8, 2006. 140 pp. (Abstract).
- Mutschler M., P. Coldschmied, E. Cobb, D. Lo Parco and J. Lorbeer. 2006. Transfer of Botytis leaf blight resistance from Allium roylei to onion (Allium cepa L.). p.14. In: Proceedings of 2006 National Allium Research Conference, College Station, Texas. December 7-8, 2006. 140 pp. (Abstract).
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Progress 01/01/05 to 12/31/05
Outputs
(1) Population levels of Aspergillus niger (cause of black mold) detected in commercial onion fields in Orange County, New York (muckland soil) when combined with results from laboratory temperature studies indicated that for infection of onion seedlings by soilborne inoculum of A. niger to occur, a high level of inoculum in the soil is required. In laboratory studies at 20 C, a level of greater than 7,000 conidia per gram of air dried soil (ads) was required to infect 20 percent of the seedlings. At higher temperatures, lower levels of the fungus resulted in higher levels of infection. Soil temperatures in Orange County during late March, April, and early May at soil depths in which onion seedlings germinate and grow can at times be 68 F and higher. Therefore, temperatures in Orange County muckland soils cropped to onions can be favorable for infection of onion seedlings by soilborne inoculum of A. niger during the planting season wherever propagule levels of the
fungus are 7,000 conidia per gram of ads or higher. (2) A cooperative trial evaluating selected fungicides and their combinations for control of onion leaf diseases was conducted in western New York on transplant onions. Because of extremely hot weather during July, the only leaf disease which occurred was Alternaria purple blotch at a low level. Data analysis indicated there were no difference in purple blotch control among the treatments. However, in one replication on a visual basis, the best treatment for controlling purple blotch was the standard mancozeb-chlorothalonil combination. In that replication, which was located on the shallowest muckland soil in the trial, Pristine and the other fungicides and their combinations tested based on the visual observation did not control purple blotch. (3) The cooperative effort with Cornell plant breeders in developing onion germplasm resistant to Botrytis leaf blight from an Allium roylei source continued successfully during 2005. Plants
with the greatest resistance to the disease now strongly resemble onion plants with normal sized bulbs. (4) Onion seed treatments with Raxil under field conditions as in previous years resulted in good control of the onion smut disease. (5) Onion seedlings grown from seed inoculated with conidia of Botrytis allii and then coated with Incotec binder became systemically infected with the fungus. Initial infection was through the cotyledon. Placement of fully developed and systemically infected seedlings in a mist chamber at 68 F for 5 days with continuous leaf wetness resulted in sporulation of B. allii on the cotyledons of the seedlings. (6) In a cooperative study with Cornell Cooperative Extension personnel, it was demonstrated that selected onion transplants grown and then shipped to New York from sources outside of the state were infected with B. allii. Plants grown form such transplants can develop a transplant Botrytis disease. On such plants large numbers of conidia of B. allii
are produced which can infect onion plants growing nearby or in adjacent fields leading to Botrytis neck rot in storage.
Impacts
Research conducted during 2005 continued to prove that systemic infection of onion seedlings by Aspergillus niger (and plants developed from the infected seedlings) can result from seedborne and soilborne inoculum of the fungus. A. niger also can infect wounded portions of onion plants during their growth and at harvest when either propagules of the fungus carried on windborne muckland soil particles or airborne conidia of the fungus are deposited on the plants. New York onion growers will be advised during 2006 that procedures for control of black mold should include seed treatments, crop rotation to reduce inoculum levels of A. niger in the muckland soils, undercutting and windrowing to completely dry the neck tissues of the plants prior to harvest, and placement of onions during storage under as cool and dry conditions as possible. Continued testing of traditional and new fungicides will provide growers with information concerning materials that will control onion
leaf diseases. The development of germplasm resistant to Botrytis leaf blight will lead to onion varieties resistant to the disease and help minimize fungicide usage. Continued biological and seed treatment studies will lead to procedures for controlling B. allii causing Botrytis neck rot and the transplant Botrytis disease. The use of Raxil and other fungicides as seed treatments to control onion smut and other seedborne pathogens should allow New York onion growers to discontinue using drench treatments and thereby increase efficiencies in planting and avoid soil compaction problems.
Publications
- Mutschler, M., Goldschmied, P., Cobb, E., LoParco, D., and Lorbeer, J. 2005. Progress towards transfer and mapping Alium roylei derived Botrytis leaf blight resistance in onion. pp. 104-106. In: Proceedings of 2005 Empire State Fruit and Vegetable Expo and Produce Marketing Conference. Syracuse, New York. February 14-17, 2005. 188 pp.
- Seyb, A.M., and Lorbeer, J.W. 2005. Identifying the inoculum potential in New York organic soils of Aspergillus niger pathogenic to onion. pp. 111-114. In: Proceedings of 2005 Empire Fruit and Vegetable Expo and Produce Marketing Conference. Syracuse, New York. February 14-17, 2005. 188 pp.
- Seyb, A.M., LoParco, D.P., and Lorbeer, J.W. 2005. The inoculum potential and population dynamics of Aspergillus niger in New York organic soils. Phytopathology 95:S95.
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Progress 01/01/04 to 12/31/04
Outputs
(1) Because the fluorescence of onion plant tissue corresponded to that for Aspergillus niger isolates transformed with a gene encoding for a green fluorescent protein, it has not yet been possible even after several experimental modifications to relate the presence of the isolates to specific tissues in onion plants in which the transformed isolates were determined to be latent by isolation and gene marker procedures. Therefore, a gene encoding for a red fluorescent protein was utilized to transform isolates of A. niger with that gene. Although several isolates were transformed (colonies grew on hygromycin amended agar indicating successful transformations), the red fluorescent protein has yet to be expressed in the isolates. Efforts are underway to resolve this problem. Propagule levels of A. niger in muckland soils cropped to onion ranged on average from 1000 to 6000 propagules per gram dry weight of soil in Oswego County and from 10000 to 25000 propagules in
Orange County. Muckland soils in Orange County cropped to onions for at least two growing season had higher populations of the fungus than soils cropped to pumpkin, squash, or left fallow. A glasshouse study including summer squash, butternut squash, pumpkin, pea, corn, soybean, and onion is ongoing to determine the role of these crops in regulating soil populations of A. niger in a muckland soil. (2) The most effective treatments to control a combination of Botrytis leaf blight and Alternaria purple blotch, both of which occurred at low disease levels in the 2004 fungicide trial, were Penncozeb 75DF at a full rate (3.2 lb/A) combined with Quadris 2.08F at a half rate (1.0 pt/A) and Bravo Ultrex 82.5WDG at a full rate (1.82 lb/A) combined with Quadris 2.08F at the half rate. A three way mixture of Penncozeb 75DF (full rate), Quadris 2.08F (half rate), and Switch 62.5WG (half rate was 1.0 lb/A) and a three way mixture of Bravo Ultrex 82.5 WDG (full rate), Quadris 2.08F (half rate), and
Switch 62.5WG (half rate) as well as a two way mixture of Switch at the full rate (2.0 lb) and Quadris (half rate) were a bit less effective in controlling the combination of the two diseases. Those combinations were more effective in controlling the diseases than several different rate combinations of Penncozeb and Bravo Ultrex. Penncozeb and Bravo Ultrex each applied individually at the full rate resulted in very little disease control. Switch at the full rate gave moderate disease control. Similar control was achieved with a Bravo Ultrex (full rate) and Switch (half rate) combination as well as a Penncozeb (full rate) and Switch (half rate) combination. (3) The cooperative effort with Department of Plant Breeding and Genetics in developing onion germplasm resistant to Botrytis leaf blight continued successfully during 2004. (4) Onion seed treatments with Raxil resulted in good control of onion smut. (5) Inoculation of onion seeds and seedlings with conidia of Botrytis allii
resulted in infection of the seedling radicles and roots developed from the seeds and the cotyledons and first leaves of the seedlings. B. allii subsequently formed conidiophores and conidia on those tissues.
Impacts
The utilization of A. niger isolates transformed with genes encoding for green and red fluorescent proteins will allow the utilization of marker isolates in future studies leading to increased knowledge of the nature of latency of the fungus in onion plants. Future research on A. niger, not only as a latent pathogen in onion seedlings and plants but also on its ecology in New York muckland soils cropped to onion, will lead to an increased understanding of etiological, ecological, and epidemiological aspects of its pathogenicity on onions and ultimately to improved procedures for New York onion growers to control the black mold disease caused by the fungus. The testing of traditional and new fungicides and their combinations will continue to provide New York onion growers with the fungicides needed for successful control of onion leaf diseases. The cooperative effort with the Department of Plant Breeding and Genetics in developing resistant germplasm to Botrytis leaf
blight ultimately will result in onion varieties resistant to the disease and thus either eliminate or greatly reduce the dependency on fungicides for control of the disease. Continued etiological, ecological, epidemiological, and seed treatment studies will lead to advances in procedures for controlling B. allii. The use of Raxil and other fungicides as seed treatments to control onion smut and damping-off diseases should allow New York onion growers to discontinue the use of drench treatments which can potentially cause soil compaction problems and impact negatively on efficiencies in planting.
Publications
- Goldschmied, P., Lorbeer, J., LoParco, D., Cobb, E., and Mutschler, M. 2004. Progress towards mapping Allium roylei derived Botrytis Leaf Blight resistance in onion. pp. 75 (Abstract). In: Proceedings of 2004 National Allium Research Conference. Grand Junction, Colorado. 250 pp.
- Haudenshield, J. S., Lorbeer , J. W., Gundersheim, N. A. and Mark, G. L. 2004. Ecological dynamics of Burkholderia cepacia causing canker-sour skin of onions and integrated pest management approaches leading to control of the disease. pp. 139-147. In: Proceedings of 2004 National Alllium Research Conference. Grand Junction, Colorado. 250 pp.
- Lorbeer, J. W. 2004. Biology and control of Botrytis species pathogen to onions, conceptual developments. pp. 8. In: Book of Abstracts. XIII International Botrytis Symposium. Antalya, Turkey. 179 pp.
- Lorbeer, J. W. 2004. Evolving concepts concerning the nature and control of Botrytis species pathogenic to onion . pp. 95 (Abstract). In: Proceedings of 2004 National Allium Research Conference. Grand Junction, Colorado. 250 pp.
- Lorbeer, J. W., Seyb, A. M., de Boer M., and van den Ende, J. E. 2004. Botrytis species on bulb crops. pp. 273-294. In: Botrytis: Biology, Pathology and Control. Edited by Y. Elad, B. Williamson, Paul Tudzynski, and Nafiz Delen. Kluwer Academic Publishers. Dordrecht/Boston/London. 428 pp.
- Seyb, A. M., LoParco, D. P., and Lorbeer, J. W. 2004. Infection of onion seedlings by soilborne inoculum of Aspergillus niger expressing green fluorescent protein. Phytopathology 94:594. Publication No. P-2004-0643-AMA. American Phytopathology Society.
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Progress 01/01/03 to 12/31/03
Outputs
(1) Specific winter cover crops grown on organic soils cropped to onion generally were effective in suppressing the population levels of the bacterium Burkholderia cepacia (cause of the bacteria canker-sour skin disease of onions) in the soils of five different fields. In the first of two trials, plots planted to buckwheat or hairy vetch had the lowest average population [20,000 colony-forming units (CFU) per gram dry weigh (DW) of soil]. Plots sown to field pea or left fallow had the highest average population (75,000 CFU). Plots seeded to yellow mustard or red clover had an intermediate average population (45,000 CFU). In the second trial, buckwheat and hairy vetch had the highest average population (25,000 CFU). Yellow mustard and red clover had the lowest average population (5,0000 CFU). Barley and sprint (blend of field pear and oat) had an intermediate average population (14,000 CFU). Several factors may have caused the reversal of the most effective and least
effective crops in the second experiment compared to the first in suppressing B. cepacia populations. However, generally it appears that hairy vetch is the most promising winter cover crop of those studied in suppressing populations of B. cepacia. The results of the experiments indicated the durability of hairy vetch in maintaining the suppression of B. cepacia populations is strong. Conversely the durability for yellow mustard and red clover appears passive. Additional experiments are needed to determine that feature for buckwheat. (2) Attempts to transform A. niger with the green fluorescent protein (GFP) were successful during 2003. Several transformed cultures of A. niger were utilized in pathogenicity studies to confirm that the transformed cultures were as pathogenic to onion as the cultures from which they were derived. In the pathogenicity experiments conducted, all of the transformed cultures tested were pathogenic and were recovered from the onion seedlings they had
infected. Additional onion seedlings and the resulting onion plants infected by the transformed cultures are now being used to study the nature of the endophytic presence and growth patterns of the fungus, at first in tissues of the seedlings and then in tissues of the resulting plants. Fluorescence microscopy is being used to determine the specific tissues in which the fungus (transformed cultures) grows and resides as an endophyte prior to causing black mold. (3) Results of a fungicide trial conducted during 2003 indicated the continued failure of the ethylenebis-dithiocarbamate fungicide mancozeb to control Botrytis leaf blight. However, when mancozeb was combined with chlorothalonil and/or Quadris in two and three way mixtures, each mixture was very effective in controlling Botrytis leaf blight as well as Alternaria purple blotch. Several other fungicides combinations tested showed promise in controlling the two leaf diseases. The promising development of germplasm for resistance
to Botrytis leaf blight continued during 2003 in the cooperative program with Cornell plant breeders.
Impacts
The results of studies completed thus far strongly indicating the suppression of B. cepacia (cause the bacterial canker-sour skin disease of onions) by growing specific rotational and winter cover crops on organic soils cropped to onions will encourage New York onion growers to adopt either one or both of the practices. It is anticipated that not only would the incidence of bacterial canker-sour skin be reduced by grower use of the practices, but also the occurrence of a number of other diseases of onion would be minimized. The successful transformation of A. niger cultures with the GFP and infection of onion seedlings by the transformed cultures should allow visual demonstrations by fluorescence microscopy during the upcoming year as to the nature of the fungus as an endophyte in onion plants prior to causing black mold of onion bulbs at harvest and in storage. Visual demonstrations made to onion growers of this nature of the biology of A. niger should encourage the
growers to use only onion seed not harboring the fungus for planting and thereby reduce the potential occurrence of black mold in the onions they grow from seed. Annual testing of traditional and new fungicides for control of onion leaf diseases has continued to provide New York onion growers with the critical information they need concerning the most effective fungicides and fungicide combinations to use to suppress the diseases. The development of onion germplasm for resistance to Botrytis leaf blight and other leaf diseases ultimately will result in reduced fungicide usage on New York onion farms.
Publications
- Haudenshield, J. S., and Lorbeer, J. W. 2003. Mediation of Burkholderia cepacia populations in organic soils by winter cover crops. p. 128. In: 8th International Congress of Plant Pathology Volume 2 offered papers, 9.23. (Abstract). 386 pp. Christ Church, New Zealand, February 1-7, 2003.
- Lorbeer, J. W. 2003. Botrytis leaf blight of onions. P. L2-5A. In: Proceedings of Botrytis Workshop at 8th International Congress of Plant Pathology, Christ Church, New Zealand, February 1-7, 2003.
- Lorbeer, J. W. 2003. Botrytis neck rot of onions. P. L2-5B. In: Proceedings of Botrytis Workshop at 8th International Congress of Plant Pathology, Christ Church, New Zealand, February 1-7, 2003.
- Lorbeer, J. W., Haudenshield, J. S., and Tuffley, J. W. 2003. Nature and management of bacterial canker-sour skin, black mold, smut, leaf blight, and seedborne disease of onion. pp. 162-166. In: Proceedings of the 2003 New York State Vegetable Conference. 232 pp. New York State Vegetable Growers Association, P.O. Box 70. Kirkville, NY 13082-0070.
- Haudenshield, J. S., Gundersheim, N. A., Mark, G. L. and Lorbeer, J. W. 2002. Multiseasonal population dynamics of Burkholderia cepacia in organic soils. pp. 119-126. In: Proceedings of 2002 National Allium Research Conference. 132 pp. December 11-14, 2002, Pasco, Washington.
- Haudenshield, J. S., Gundersheim, N. A., Mark, G. L., and Lorbeer, J. W. 2003. Multi-seasonal population dynamics of Burkholderia cepacia in organic soils cropped to onion, and the influence of non-onion crops. Phytopathology 93:534. (Abstract).
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Progress 01/01/02 to 12/31/02
Outputs
Assays of soil samples from fields cropped to onions and other crops during 2002 for population levels of Burkholderia cepacia, the cause of the bacterial canker-sour skin disease, indicated that the levels of the bacterium in soils cropped to onions varied from 20,000 to 200,000 colony forming units (CFU) per gram of air dried soil. Soils with a history of onion culture on which corn, geen beans, and pumpkin were grown showed significant levels of B. cepacia (up to 39,900, 20,300, and12,200 CFU/g soil, respectively). Other fields previously cropped to onions and then planted to radish repeatedly, radish and lettuce in succession, squash, soybean, and turfgrass had moderate or very low levels of B. cepcia resident in the soils. In turfgrass fields the levels ranged from 0 to 635 CFU/g of soil. For squash, soybean, and radish alternated with lettuce, the levels were 647, 825, and 909 CFU/g of soil, respectively. Radish fields sampled ranged from 647 to 8,230 CFU/g of
soil. In a miniculture system great differences were detected among the crops tested. Corn and soybean elicited over a 500 percent increase in the soilborne B. cepacia population levels. Millet, carrot, and beets reduced the levels of B. cepacia. Other crops found to induce only low-level increases of B. cepacia were turnip, radish, tomato, lettuce, pepper, and wheat. When onion seeds contaminated with Aspergilus niger, the fungus which causes black mold, were planted in soil not containing the fungus or when onion seeds not contaminated with A. niger were planted in soil artificially infested with the fungus, the roots, basal plates, cotyledons, and leaves of the resulting seedlings and plants became infected but without symptoms. When similarly infected seedlings were grown to plant maturity, A. niger survived in the onion plants without producing macroscopic signs of the fungus until plant maturity at which time symptoms of black mold became apparent either then or after the onions
were harvested. It also appears that onion plants not harboring A. niger can become infected with the fungus as the plants mature or at harvest. It is postulated that typical symptoms of black mold under the outer scales as well as neck region decay can result from the symptomless seedling infection, and that decay of the neck region of the bulbs also may result from direct infection of onion plants late in the growing season or at harvest. The levels of A. niger in soils of fields cropped to onions differed substantially between the fields (between 0 to 15,000 propagules of A. niger per gram of air dried soil) perhaps due to differences in cropping patterns or other cultural practices. During 2001 the levels ranged between 1,000 to 14,000 propagules per gram of air dried soil. Differences between fields possibly could lead to different occurrence levels of black mold on onions grown on the different fields. The environmentally friendly fungicides Quadris and Switch used in
combination with mancozeb or chlorothalonil continued to control leaf diseases of onions in 2002. Raxil as a seed treatment gave good control of onion smut.
Impacts
Several crops which have the potential of reducing Burkholderia cepacia levels in soils cropped to onions were identified during 2002. The most promising are radish, lettuce, squash, soybean, and turfgrass. It is anticipated that onion growers will consider this new knowledge as they plan programs for rotating onions with other crops to reduce the potential for the occurrence of the bacterial canker-sour skin disease caused by B. cepacia. The importance of seed transmission of Aspergillus niger causing the black mold disease of onions and its role as endophyte in onion plants until they mature and symptoms of the diseases occur was demonstrated. Eventually growers will insist that seed companies must provide seed free of the pathogen. Since A. niger can survive in soils cropped to onions, growers will become interested in developing cultural procedures and crop rotation programs to reduce inoculum levels of the pathogen in their fields. Future registration of Raxil as
a seed treatment for onion smut control would allow planting procedures without a water carrier thereby speeding up the planting process and avoiding the extra weight of the water on the planting equipment thereby creating less soil compaction. Quadris is now registered for use on onions in New York and it is anticipated that Switch will receive registration for use in New York within the near future.
Publications
- Lorbeer, J. W., Tuffley, J. W., Ransom, V. E., and Snover, K. L. 2002. The nature of Aspergillus niger as an endophytic fungus in onion plants and subsequent development of black mold. pp. 43-45. In: Proceedings of 2002 National Allium Research Conference. Washington State University. 132 pp.
- Mark, G. L., Gitaitis, R. D., and Lorbeer, J. W. 2002. Bacterial Diseases of Onion. pp. 267-292. In: Allium Crop Science: Recent Advances. Edited by H. D. Rabinowitch and L. Currah. Published by CABI International, Wellingford, United Kingdom. 515 pp.
- Tuffley, J. W., and Lorbeer, J. W. 2002. Endophytic activity of Aspegillus niger in onion. Phytopathology 92:S82. (Abstract).
- Lorbeer, J. W., Kuhar, T. P., and Hoffmann, M. P. 2002. Monitoring and Forecasting for Disease and Insect Attack in Onions and Allium Crops within IPM Strategies. pp. 293-309. In: Allium Crop Science: Recent Advances. Edited by H. D. Rabinowich and L. Currah. Published by CABI International, Wellingford, United Kingdom. 515 pp.
- Lorbeer, J. W., Tuffley, J. W., Ransom, V. E., and Snover, K. L. 2002. The nature of Aspergillus niger as an endophytic fungus in onion plants and subsequent development of black mold. p. 20. In: Conference Abstracts of 2002 National Allium Research Conference. Washington State University. 58 pp.
- Haudenshield, J. S., Gundersheim, N. A., Mark, G. L., and Lorbeer, J. W. 2002. Population dynamics of Burkholderia cepacia in organic soil. Phytopathology 92:S35. (Abstract).
- Lorbeer, J. W. 2002. Disease management of bacterial canker-sour skin, black mold, smut, and the leaf blight diseases of onion in 2001. pp. 106-110. In: Proceedings of the 2002 New York State Vegetable Conference and Berry Growers Meeting. New York State Vegetable Growers Association, P.O. Box 4256, Ithaca, NY 14852.
- Lorbeer, J. W., Haudenshield, J. S., Gundersheim, N. A., and Mark, G. L. 2002. Multiseasonal population dynamics of Burkholderia cepacia in organic soils. p. 53. In: Conference Abstracts of 2002 National Allium Research Conference. Washington State University. 58 pp.
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Progress 01/01/01 to 12/31/01
Outputs
Field studies conducted during 2001 and previously have indicated when muckland soils are maintained in continuous onion production, population levels of Burkholderia cepacia causing the bacterial canker-sour skin disease of onions at first increase and then decrease from the elevated levels during the growing season. During 2001 it was learned the population levels also rise again after harvest of the onions for a yet to be determined time period. Sampling of field soils during 2001 indicated that selected onion fields rotated to lettuce/radish, turf, and soybeans had extremely low populations of B. cepacia. A miniculture procedure, for use under controlled environmental conditions, was developed during 2001 to determine which other potential rotational crops and plant species regulate population levels of B. cepacia in New York muckland soils cropped to onion. The procedure developed during recent months thus far has indicated that corn greatly increases the levels
of B. cepacia in the soils while several selections of wheat decrease the levels. Thus corn is a crop to avoid growing on New York onion soils and wheat is a crop to consider for rotating with onions as well as for use as a winter cover crop and/or an organic windbreak for onion seed and seedling blowout control. Studies conducted during 2001 on Aspergillus niger causing black mold of onions proved the endophytic nature of the fungus in onion plants. Seedlings infected with the fungus from seedborne and soilborne sources developed into plants that continued to harbor the fungus in a symptomless manner. At harvest, although only some of the bulbs from the plants were visually detected with black mold symptoms, after a short heat and high moisture treatment at 86 or 92 F all of the bulbs developed black mold. Physiological changes in onion plants as they mature and/or environmental conditions such as high temperatures and moisture levels appear to regulate the change of A. niger from
the endophytic symptomless behavior to that of a pathogenic nature. In that respect, when the upper portion of a seed stalk and the connected flower head, both of which appeared healthy, although they were from one of the infected plants in the 2001 experiment, were placed in a high humidity chamber at laboratory temperature, A. niger from internal endophytic presence in the flower head subsequently developed heavy sporulation over the entire flower head after several days of incubation. In another study conducted during 2001, the population levels of A. niger in the soils of nine fields cropped to onion differed substantially between the fields (between 1,000 to 15,000 propagules of A. niger per gram of air dried soil). These differences possibly could lead to different occurrence levels of black mold on onions grown on the different fields. Experiments with the environmentally friendly new fungicides Quadris and Switch indicated the materials continue to look promising in
controlling leaf diseases of onion. The new fungicide Raxil used as a seed treatment continued to give good control of onion smut.
Impacts
Research conducted during 2001 indicated that bacterial canker-sour skin of onions caused by B. cepacia can eventually be managed by the use of rotational crops. Onion growers will now be much more willing to experiment at the commercial level with different crops rotated with onions to control the bacterial disease and be less likely to rely upon pesticides in an attempt to control the disease. Since A. niger is now understood to be a seedborne and soilborne pathogen of onion which can become endophytic in onion plants and then cause black mold in the onion bulbs at harvest and in storage, growers will pay more attention to the use of seed free of the fungus as well as consider the use of crop rotation to lower levels of the fungus in the soil of onion fields which have had a history of black mold and/or are detected to harbor high levels of the fungus in the soil. Since it is suspected that the previous cropping pattern of a field is also a factor that may enhance
elevated levels of A. niger in the soil, the selection of rotational crops for onion will become an important grower decision for control of black mold. The availability of the environmentally friendly fungicides Quadris and Switch will provide New York growers with an enhanced arsenal of materials to control onion leaf diseases and lesson concerns for quality of the environment. The effectiveness of Raxil as a seed treatment for control of smut and damping off diseases will allow growers to control the diseases without the use of a water carrier which they have desired to accomplish.
Publications
- Lorbeer, J. W. 2001. Bacterial diseases and black mold of onions. In: Education Session of Great Lakes EXPO 2001 (Fruit, Vegetable and Farm Market). pp. 49-50. Grand Rapids, Michigan.
- Lorbeer, J. W. 2001. Chemical control of four leaf diseases of onion in an IPM mode in New York. In: Proceedings of the Third International Symposium on Edible Alliaceae. pp. 226-227. Athens, Georgia.
- Lorbeer, J. W. 2001. Disease management of the leaf blight, bacterial canker-sour skin, black mold, and smut diseases of onion during 2000. In: Proceedings of the 2000 New York Vegetable Conference. pp. 161-166. New York State Vegetable Growers Association, Ithaca, New York.
- Lorbeer, J. W. 2001. Nature and control of onion diseases - current status and future prospects. Plant Pathology Keynote Address. In: Proceedings of the Third International Symposium on Edible Alliaceae. pp. 133-138. Athens, Georgia.
- Lorbeer, J. W. 2001. Soilborne and leaf blight diseases of onions. In: Education Session of Great Lakes EXPO 2001 (Fruit, Vegetable and Farm Market). pp. 45-46. Grand Rapids, Michigan.
- Lorbeer, J. W., Petzoldt, C. H., and Walters, T. W. 2001. Integrated pest management of Botrytis leaf blight of onion. Acta Horticulturae 555:129-132.
- Mark, G. L., and Lorbeer, J. W. 2001. Population dynamics of Burkholderia cepacia in organic soils cropped to onions and rotational crops throughout two successive growing seasons. pp. 228-230. Athens, Georgia.
- Mark, G. L., and J. W. Lorbeer. 2001. Population dynamics of the onion phytopathogen Burkholderia cepacia in organic soil cropped to onion. In: Plant Pathogenic Bacteria. S. H. DeBoer, ed. Kluwer Acadmemic Publishers, Dordrech, The Netherlands. pp. 315-318.
- Mark, G. L., and J. W. Lorbeer. 2001. The response of three phenotypically variable Burkholderia cepacia isolates to copper-based bactericides. In: Plant Pathogenic Bacteria. S. H. DeBoer, ed. Kluwer Academic Publishers, Dordrech, The Netherlands. pp. 341-344.
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Progress 01/01/00 to 12/31/00
Outputs
After testing a number of selective media for effectiveness in assaying for the presence of Aspergillus niger in organic soils cropped to onion, Prune Lactose Yeast Agar (PLYA) proved to be the most suitable for the purpose. Using PLYA the numbers of propagules of A. niger/g soil (air dried) in seven fields with different histories of levels of black mold caused by the fungus were 0.0, 0.3, 0.3, 0.6, 1.0, 2.8, and 3.9 x 1000 propagules. The substitution of lactic acid for the two antibiotics in PLYA and the addition of Rose Bengal has enhanced the effectiveness of the selective medium now designated as RAPLYA to monitor the levels of soilborne as well as airborne propagules of A. niger. Limited trapping of airborne conidia of A. niger in the canopy of onion plants detected much lower levels of A. niger than anticipated. The relative importance of airborne inoculum of the fungus in the disease cycle of black mold remains to be determined. In organic soils continuously
cropped to onion, population levels of Burkholderia cepacia causing bacterial canker and sour skin of onion increased during the first months of the growing season (April to late June or early July) and then decreased during July or August to the levels detected in April. Populations of B. cepacia in soils rotated with lettuce did not increase during the April to July period and ended at levels equal to or less than those detected in April.
Impacts
The understanding that A. niger can colonize the organic soils of fields cropped to onion, and was either not present or detected at very low to elevated propagule levels for those onion fields assayed, clearly indicates the potential importance of soilborne inoculum of the fungus in the disease cycle of black mold, particularly for those fields containing elevated levels of the fungus. It would presently appear that management of the disease will need to involve crop rotation considerations as well as the use of seed free of contamination by the fungus. Crop rotation would also appear to be the most promising procedure for managing bacterial canker and sour skin caused by B. cepacia.
Publications
- Mark, G. L. and Lorbeer, J. W. 2000. The response of three phenotypically variable Burkholderia cepacia isolates to copper-based bactericides. Poster 30. In: The 10th International Conference on Plant Pathogenic Bacteria Conference Program and Abstracts. (Abstract).
- Ransom, V. E. 2000. Investigation of potential inoculum sources of Aspergillus niger, the cause of black mold of onion. MPS Thesis. Department of Plant Pathology, Cornell University, Ithaca, NY. 89 pp.
- Lorbeer, J.W. 2000. Integrated pest management of Botrytis squamosa causing Botrytis leaf blight of onion. Paper L39. XIIth Intenational Botrytis Symposium. July 3-7, 2000. Reims, France. (Abstract).
- Lorbeer, J.W., Delen, N. and Tosun, N. 2000. Chemical Control. In: Encyclopedia of Plant Pathology, pp. 199-203, Volume 1. Edited by O.C. Maloy and T.D. Murray. Published by John Wiley and Sons, Inc., New York.
- Lorbeer, J.W., Mark, G.L., Snover, K. L. and Karp, M.A. 2000. Characterization and management of the bacterial, black mold, leaf blight, and smut diseases of onions. In: Proceedings of 2000 New York State Vegetable Conference. pp. 146-150.
- Mark, G.L. and Lorbeer, J.W. 2000. Burkholderia cepacia (sourskin): Its etiology in onions, population dynamics in organic soil, and response to copper based formulations. In: Proceedings of 2000 New York State Vegetable Conference. pp. 140-145.
- Mark, G.L. and Lorbeer, J. W. 2000. Population dynamics of the onion phytopathogen Burkholderia cepacia in organic soil cropped to onion. Paper 024. In: The 10th International Conference on Plant Pathogenic Bacteria Conference Program and Abstracts. (Abstract).
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Progress 01/01/99 to 12/31/99
Outputs
Onion flower heads were inoculated with spores of A. niger at 6 different stages of development from the period of tight flower head formation before the flowers opened to mature seed capsule formation. A seventh treatment involved inoculation of onion seed stalks by injection of spores of A. niger into the lacunar area of the seed stalks. The eighth treatment was the control. Umbels were collected at seed head maturation, dried, and the seed separated. The seed from each treatment was divided into 3 lots (not washed, washed, surface sterilized) and tested for the presence of A. niger. The sterilization treatment eliminated A. niger on the surface of the seed. The later the flower heads were inoculated the greater was the level of infestation (seed surface colonization by A. niger) and infection (internal colonization of the seed by A. niger. Internal infection of the seed averaged from 78-95% for the stages from full flower formation to mature seed capsule formation.
Treatment at earlier stages of formation had less than 46% of the seed internally infected by A. niger. Inoculation of seed stalks resulted in low levels of internal infection of onion seed (less than 5%) by A. niger. Onion seedlings become infected by seedborne inoculum of A. niger and this may lead to outbreaks of Black Mold in mature onion bulbs.
Impacts
The knowledge that seedborne inoculum of A. niger invades onion seedlings, symptomlessly ramifies through root and leaf tissue, and becomes imbedded in the basal plate indicates an endophytic relationship with the onion until plant maturity when the fungus becomes pathogenic causing Black Mold. This knowledge indicates that control of the disease should begin with seed not harboring A. niger.
Publications
- Lorbeer, J.W., Gundersheim, N.A. and Mark, G.L. 1999. Present status of bacterial diseases of onion and their control in New York. In: Proceedings of the 1998 National Onion (and other Allium) Research Conference. December 10-12, 1998, Sacramento, California. pp. 209-212.
- Lorbeer, J.W. 1999. Nature and control of onion diseases in New York. In: Proceedings of Third Scientific Conference on Onions in the Mercosur. August 30-31, 1999, Salto, Uruguay. pp. 123-129.
- Lorbeer, J.W., Mark, G.L., Gundersheim, N.A., Sirois, K.L., Holcomb, M. A. and LoParco, D.P. 1999. Biology and management of bacterial diseases, black mold, and leaf blights of onion. In: Proceedings of 1999 New York State Vegetable Conference. pp.134-137.
- Mark, G.L., Lorbeer, J.W. and Gundersheim, N.A. 1999. Characterization and quantification of Burkholderia cepacia isolated from onions and organic soil previously cropped to onion. Phytopathology 89:548. Publication No. P. 1999-0341-AMA. (Abstract).
- Sirois, K.L. and Lorbeer, J.W. 1999. Susceptibility of onion seed stalks and flowers to infection by Aspergillus niger Teigh. In: Proceedings of the 1998 National Onion (and other Allium) Research Conference. December 10-12, 1998, Sacramento, California. pp. 231-237.
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Progress 01/01/98 to 12/31/98
Outputs
Leaves of onion plants wounded or bruised at the base of the leaf axil, inoculated with Burkholderia cepacia, and maintained in a mist chamber at 30 C for one week developed typical symptoms of bacterial canker. B. cepacia then spread upward into the leaf blade tissue blighting the infected leaves and downward into the outer bulb scale resulting in typical symptoms of sour skin. This is the first experimental evidence in New York that typical sour skin decay of developing bulbs of onion plants can develop from infections through leaf axil tissue that initially exhibited typical canker symptoms. Previous experiments (Kawamoto and Lorbeer) had indicated that leaf axil tissue infected with B. cepacia which did not remain water congested resulted in blighting of the leaf but not in decay of bulb tissue. The connection of canker with sour skin bulb decay was not made at that time. A number of bacterial isolates were obtained from onion plants exhibiting bacterial canker.
Carbon metabolism (BIOLOG), colony morphology including color, and pathogenicity indicated that most isolates were B. cepacia which varied particularly with respect to colony pigmentation when grown on tryptic soil agar. Pigmentation was of three types: yellow, cream/yellow, and white. Pathogenicity of the B. cepacia isolates ranged from high to mild in an in-vitro onion slice bioassay. Bacterial ooze, tissue maceration, and water release were indicative of the highly pathogenic B. cepacia isolates.
Impacts
(N/A)
Publications
- Lorbeer, J.W., and Gundersheim, N.A. 1998. Present status of bacterial diseases of onion and their control in New York. 1998 National Onion (and other Allium) Research Conference: 33. (Abstract).
- Lorbeer, J.W. 1998. Nature and source of inoculum of Aspergillus niger causing the Aspergillus black mold disease of onions in New York. In: 1997 New York State Vegetable Project Reports Relation to IPM. Pages 110-114. NYS IPM Publication #123 (January, 1998) NYAES, Geneva, New York.
- Lorbeer, James, and Gundersheim, Norman. 1998. B. cepacia as a phytopathogen. APSnet Plant Pathology On-Line APS Symposium. "Burkholderia cepacia - Friend or Foe". Page 1 (Abstract).
- Lorbeer, J.W., Gundersheim, N.A., and Sirois, K.L. 1998. Leaf blights, bacterial diseases, and black mold of onion. In: Proceedings of the 1998 New York State Vegetable Conference. pp 198-202. New York State Vegetable Growers Association.
- Lorbeer, J.W., Petzoldt, C.H., and Walters, T.W. 1998. Integrated pest management of Botrytis leaf blight of onion. Acta Horticulturae (In press).
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Progress 01/01/97 to 12/31/97
Outputs
Botrytis leaf blight (BLB) occurred at a moderate level late in the growing season in the onion disease control experiments conducted during 1997. Other fungal or bacterial leaf blights did not occur or were present at insignificant levels. All treatments reduced levels of BLB as compared to disease levels in the no fungicide control treatments. The combination of Dithane F-45 4F and Rovral 4F gave good control of BLB as usual. The combination of Dithane F-45 4F and Bravo Weather Stik 6F gave effective control of BLB. The triple combination of Dithane F-45 4F, Bravo Weather Stik 4F, and Rovral 4F was slightly less effective than the first two combinations. Two Terranil treatments were slightly more effective than Bravo Ultrax 82.5 SDG and somewhat less effective than Bravo Weather Stik 6F. The experimental fungicide RH-141647 appeared to be most effective at the 0.582 qt rate and was one of the best treatments for the control of BLB. The fungicide Switch 62.5 WG also
was one of the best treatments for the control of BLB. Tilt 3.6 EC alternated weekly with Switch 62.5 WG was somewhat less effective. Tilt 3.6 EC applied on an alternate week schedule did not control BLB effectively. In 1996, when applied on a weekly basis, it was very effective in controlling BLB. Dithane F-45 4F applied by itself as usual performed poorly in controlling the disease. Mankocide (Mancozeb + Copper) was poor in control of BLB as rated on August 31 but resulted in the highest yield.
Impacts
(N/A)
Publications
- Coleman, P.M., Ellerbrock, L.A., and Lorbeer, J. W. 1997. Reaction of selected onion cultigens to pink root under field conditions in New York. Plant Disease 81:138-142.
- Lorbeer, J.W. 1997. Nature and source of inoculum of Aspergillus niger causing the Aspergillus black mold disease of onions in New York. Department of Plant Pathology, Cornell University, Ithaca, NY.
- Lorbeer, J.W. 1997. Onion Disease Management. In Proceedings of the 1997 New York State Vegetable Conference. pp. 174-178. New York State Vegetable Growers Association, P.O. Box 4256, Ithaca, New York
- Yohalem, D.S., and Lorbeer, J.W. 1997. Distribution of Burkholderia cepacia phenotypes by niche, method of isolation, and pathogenicity to onion. Annals of Applied Biology 130-479.
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Progress 01/01/96 to 12/30/96
Outputs
#Erwinia chrysanthemi which caused a severe bacterial decay of onion bulbs underfield conditions in Cayuga County during the hot and moist period of late July and early August of 1995 was isolated along with other onion decay causing bacteria from drainage ditch water used for drip and overhead irrigation in the same area during 1996. Although traces of the disease caused by E. chrysanthemi occurred in 1996, the disease was held in check by the relatively cool growing conditions. Similar cool growing and harvest conditions in Orange County held black mold of onion caused by Aspergillus niger in check during 1996. The occurrence of black mold is favored by high temperatures and high relative humidities such as were experienced during the summer of 1995 in Orange County where the disease was serious on a number of farms. Several lots of commercial and New York home grown onion seed were detected with high levels of infestation with A. niger. Other lots had moderate and
zero levels of infection. Tilt and the experimental fungicide RP 10673A both exhibited good control of Botrytis leaf blight (BLB) in field trials. The combination of Dithane F-45 and Rovral also gave good control and the mixture was determined to be synergistic in the action spectrum. Half dosages of Bravo 720 sprayed on selected onion cultigens (Kasmer Red, Wolska, Rawska, PI 273212 S1, and Spartan Banner 80) gave equal or better control of BLB than that obtained on other cultigens sprayed with full dosages of the fungicide.
Impacts
(N/A)
Publications
- DeMilia, M.S., Lorbeer, J. W. and Johnston, S. A. 1996. Guidelines for the analysis of synergism and other fungicide joint action effects. Phytopathology 86:(11, supplement):S121 (Abstract).
- Lorbeer, J. W. 1996. Introduction to symposium on synergism, antagonism, and additive action of fungicides in mixtures. Phytopathology 86:1261-1262.
- Lorbeer, J. W. 1996. Recent occurrences of bacterial bulb decay caused by Erwinia chrysanthemi. Proceedings of the 1995 National Onion Research Conference:135-139.
- Walters, T.W. and Lorbeer, J. W. 1996. Sources of resistance to Botrytis leaf blight of onion. Proceedings of the 1995 National Onion Research Conference:118-122.
- Walters, T. W., Ellerbrock, L. A., van der Heide, J. J., Lorbeer, J. W. and LoParco, D. P. 1996. Field and greenhouse procedures to evaluate onions for Botrytis leaf blight resistance. HortScience 31(3):436-438.
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Progress 01/01/95 to 12/30/95
Outputs
A total of 154 onion accessions, varieties, and breeding lines and 38 other Allium spp. accessions were evaluated for resistance to Botrytis leaf blight (BLB) during 1994-95. A. roylei and all A. fistulosum accessions were highly resistant. One A. cepa accession (PI 273212 from Poland), another from Macadonia (PI 357215) three open-pollinated varieties (selected by New York onion growers), and two Polish breeding lines were resistant (superficial lesions - no blighting). Since fertile hybrids between A. roylei and A. cepa can be produced, the resistance sources in A. roylei and those in A. cepa PI 273212 and the other A. cepa germplasm represent useful sources of BLB resistance. During 1994-95 two WEATHERCELL 2000 portable electronic weather stations were built, tested, and used in the on-line BLIGHT-ALERT warning system for BLB. The fungicides Fluazinum and Tilt gave promising control of BLB in 1994 (tests inconclusive in 1995). Fluazinum gave outstanding control of
lettuce drop during 1992-94. Bacterial bulb decay caused by Erwinia chrysanthemi and Aspergillus black mold caused dramatic levels of disease on onions in New York during 1995 and will need to be studied during 1996.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
A developing study on the nature of Alternaria and Stemphylium leaf diseases of onion in New York has indicated that at least two, possibly more, species of Alternaria and one pathogenic and one saprophytic species of Stemphylium are involved. During 1994 it was demonstrated that Alternaria porri causes dark purple concentric lesions, A. alternata causes brown elliptical lesions, Stemphylium vesicarium causes brown to black concentric lesions, and that S. botryosum is a primary saprophytic colonizer of necrotic onion leaves caused by pathogenesis of a number of onion leaf pathogens including Alternaria spp. and Stemphylium vesicarium. The nature of apparent direct leaf blighting by Alternaria spp. and S. vesicarium without prior lesion development in a number of instances is still not understood and is continuing to be investigated. Screening procedures involving inoculum production and inoculation procedures for determining resistance of Allium spp. and Allium cepa
(onion) cultivars and selections for resistance to Botrytis squamosa were developed for greenhouse and outdoor experiments. A misting system constructed for maintaining free moisture provided leaf wetness levels and durations that allowed for high levels of disease on susceptible cultivars.
Impacts
(N/A)
Publications
- LORBEER, J. W. 1993. Present status of Botrytis diseases of onion in New York. Proceedings of 1993 National Onion Research Conference. pp. 16-24.
- LORBEER, J. W., DEMILIA, M. S., AND MAGNUSON, S. P. 1993. Placement of BLIGHT-ALERT forecasts for Botrytis leaf blight of onion on-line in Orange County, NY during 1993. Proc. 1993 Natl. Onion Res. Conf. pp. 25-31.
- LORBEER, J. W. 1993. A serious outbreak of Stemphylium leaf blight of onion in New York. Proceedings of 1993 National Onion Research Conference. pp. 32-37.
- YOHALEM, D. S., AND LORBEER, J. W. 1994. Multilocus isoenzyme diversity among strains of Pseudomonas cepacia isolated from decayed onions, soils, and clinical sources. Systematic and Applied Microbiology 17:116-124.
- YOHALEM, D. S., AND LORBEER, J. W. 1994. Intraspecific metabolic diversity among strains of Burkholderia cepacia isolated from decayed onions, soils, and the clinical environment. Antonie van Leeuwenhoek 65:111-131.
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Progress 01/01/93 to 12/30/93
Outputs
An on-line delivery system was developed for providing commercial onion growers in Orange County, New York with recommendations from the BLIGHT-ALERT weather-based predictive system for timing fungicide applications for Botrytis leaf blight control. Computer software was developed for automated retrieval of weather data and calculation of BLIGHT-ALERT spray predictions from two SCS operated electronic weather stations BLIGHT-ALERT forecasts were then recorded on an answering machine dedicated to grower phone calls for spray predictions. A significant reduction in the number of pesticide applications necessary for successful Botrytis leaf blight disease control was obtained by the limited number of growers who used the on-line system during the summer of 1993. An implementation program is continuing for providing wide scale availability and usage of the BLIGHT-ALERT on-line system for commercial onion growers in Orange County and elsewhere in New York. Recent research
has suggested that a network of weather stations would be required to provide accurate BLIGHT-ALERT forecasts to the entire commercial onion growing region in Orange County. An inexpensive, portable, solar powered weather station, the Weathercell 2000, consisting of a microprocessor, external sensors, modem, and cellular phone, is currently under development for the establishment of such a network.
Impacts
(N/A)
Publications
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Progress 01/01/92 to 12/30/92
Outputs
Two electronic weather stations operated by the Soil Conservation Service as part of the Wallkill-Roundout Watershed Project were located during 1992 in the principal onion growing area of Orange County, New York. The reliability of BLIGHT-ALERT forecasts at distances from each station (Regelski and Jados) were determined by hygrothermographs spaced to cover a considerable area of this onion growing area and include locations where microclimates were suspected to differ from those at the weather station sites. Specific differences monitored during 1992 at several such sites and the weather station sites indicate at least one additional weather station is needed to determine general BLIGHT-ALERT forecasts for the entire area. Locations with specific microclimates (i.e. sheltered areas, lower or higher topography) may need additional monitoring for site-specific BLIGHT-ALERT forecasts. Although temperature differences between weather stations and hygrothermograph
locations occurred, they were only associated with evening and nighttime periods; significant microclimatic differences between weather stations and the specific hygrothermograph locations were predominately related to relative humidity rather than temperature. Since precise relative humidity measurements are needed for BLIGHT-ALERT forecasts, substitution of environmental micrologger units for hygrothermographs is indicated for utilization at sites of different microclimates.
Impacts
(N/A)
Publications
- LORBEER, J.W. 1992. Botrytis leaf blight of onion. pp. 186-211. In: Plant Disease of International Importance. H.S. Chaube, U.S. Singh, A.N. Muckhopadhyay (Eds.). Prentice Hall, Englewood Cliffs, NJ, USA. 376 p.
- LORBEER, J.W., AND DEMILIA, M.S. 1992. Prog. rept. of the demonstration program for placement of BLIGHT-ALERT on-line in Orange Co., NY & preparation for future regional expansion of the predictive system. Cornell U. Ithaca, 11 p.
- LORBEER, J.W., DEMILIA, M.S., AND LOPARCO, D.P. 1992. Spray trials for the control of diseases of onion & lettuce grown on organic soils in NY. pp. 97-111. Proc. 55th Ann. NYS Pest Mgmt. Conf. IPM Pub. #501. Cornell U. 210 p.
- LORBEER, J.W., DEMILIA, M.S., AND MAGNUSON, S.P. 1992. The effectiveness of BLIGHT-ALERT forecasts from a single weather monitoring location during 1992. 46 pp. Dept. of Plant Pathology, Cornell University, Ithaca, NY.
- YOHALEM, D.S., AND LORBEER, J.W. 1992. Characterization of diversity among strains of Pseudomonas cepacia isolated from clinical sources, soils, and infected onions. Phytopathology 82:248-249. (Abstract).
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Progress 01/01/91 to 12/30/91
Outputs
A weather-based predictive system (BLIGHT-ALERT) was developed in 1988 to time fungicide applications for controlling Botrytis leaf blight of onion. BLIGHT-ALERT operates after the critical disease level of 1.0 lesion per leaf has been reached and the first spray applied. This system functions by forecasting sporulation and infection periods of Botrytis squamosa. Weather parameters used in BLIGHT-ALERT were monitored during 1991 along a 3353 meter transect to determine the maximum radius for which predictive-system forecasts from a single weather-monitoring location are applicable. It was shown that the area fo reliable predictions using BLIGHT-ALERT from a single weather-monitoring location could be extended to an open area of 8727 acres. During the summer of 1991, numerous fields in Orange County, New York were monitored for the Stemphylium/Alternaria disease complex. General disease symptoms were characterized, leaf surface spore populations were analyzed, and
isolations were performed. Results suggested that Alternaria porri, causal agent of Purple blotch, and Stemphylium vesicarium, causal agent of Stemphylium leaf blight, are the primary contributing organisms to the Stemphylium/Alternaria disease complex.
Impacts
(N/A)
Publications
- DEMILIA, M.S. and LORBEER, J.W. 1992. Joint action effects of fungicides used for the control of Botrytis leaf blight of onion in New York. Phytopathology 82:242 (Abstr.).
- AWUAH, R.T. and LORBEER, J.W. 1991. Methyl bromide and steam treatment of an organic soil for control of Fusarium yellows of celery. Plant Disease 75:123-125.
- LORBEER, J.W., DEMILIA, M.S. and LOPARCO, D.P. 1991. Spray trials conducted during 1991 for the control of diseases of onion and lettuce grown on organic soils in New York. In:Proc. Fifty-Third Ann. NYS Pest Mang. Conf. Corn.
- LORBEER, J.W., DEMILIA, M.S. and MAGNUSON, S.P. 1991. A study conducted during 1991 of the effectiveness of BLIGHT-ALERT at increasing distances from the weather monitoring site. Dept. Plant Pathol., Cornell U., Ithaca, NY. 1.
- LORBEER, J.W., DEMILIA, M.S. and SCHOTTHOEFER, A.M. 1991. A study conducted during 1991 of the disease symptoms of the Stemphylium/Alternaria disease complex in New York. Dept. Plant Pathol., Cornell Univ., Ithaca, NY. 9 pp.
- RIST, D.L. and LORBEER, J.W. 1991. Relationships of weed reservoirs of cucumber mosaic virus (CMV) and broad bean wilt virus (BBWV) to CMV and BBWV in commercial lettuce fields in New York. Phytopathology 81:367-371.
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Progress 01/01/89 to 12/30/89
Outputs
An infection index for Botrytis squamosa was developed that uses temperature andleaf wetness duration to categorize leaf wetness episodes as insignificant, slight, moderate, or severe potential infection periods, given the presence of inoculum. Using this infection index, it was found that the frequency and severity of potential infection periods of B. squamosa in a commercial onion field in Orange County, NY, increased with increasing National Weather Service (NWS) precipitation probability (PP). Severe potential infection periods occurred in 0, 18, 24, and 84% of the 36-hr. forecast periods in which the maximum PP for the forecast period was <30, 30-40, 50-60, and >70%, respectively. It was concluded that a PP > 30% could be used to forecast severe potential infection periods of B. squamosa. A standard meterological score for assessing forecasting skill was used to evaluate the accuracy of PP forecasts in forecasting measurable precipitation (>1.3 mm) in a
commercial onion field. In contrast to a reported trend among NWS forecast offices of declining forecasting skill with increasing time after issurance of a forecast, skill of PP forecasts for the Lower Hudson Valley in New York (which includes Orange County) remained high for 36 hr following the forecast. This indicated that the use of PP> 30% as a decision rule for forecasting severe potential infection periods of B. squamosa should have equal predictive value for up to 36 hr in advance.
Impacts
(N/A)
Publications
- AWUAH, R.T. and LORBEER, J.W. 1989. Role of light, temperature, and method of propagation in cultural variability of Fusarium oxysporum f. sp. apii race 2. Mycologia 81:278-283.
- AWUAH, R.T. and LORBEER, J.W. 1989. A procedure for isolating Pyrenochaeta terrestris from onion roots. Ann. Appl. Biol. 114:205-208.
- LORBEER, J.W. and VINCELLI, P.C. 1989. Efficacy of dicarboximide fungicides for controlling Botrytis leaf blight of onion in New York. Proc. Nat. Onion Res. Conf., Denver, CO, Dec. 10-11, 1987. pp. 55-61. April 1989, 64 pp.
- LORBEER, J.W., ELLERBROCK, L.A. and RAMSEY, G.R. 1988. Production of healthy onion seed by applying fungicide sprays to seed onions during flowering. 5th Intern'l Congress of Plt Path, Paper 4-1, p. 405.
- RIST, D.L. and LORBEER, J.W. 1989. Occurrence and overwintering of cucumber mosaic virus and broad bean wilt virus in weeds growing near commercial lettuce fields in New York. Phytopathology 79:65-69.
- SHISHKOFF, N. and LORBEER, J.W. 1989. Etiology of Stemphylium leaf blight of onion. Phytopathology 69:301-304.
- VINCELLI, P.C. and LORBEER, J.W. 1989. BLIGHT-ALERT: A weather based predictive system for timing fungicide applications on onion before infection periods of Botrytis squamosa. Phytopathology 79:493-498.
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Progress 01/01/88 to 12/30/88
Outputs
Previously published modesl (sporulation index model and Botcast) fore forecasting sporulation by B. squamosa frequently failed to forecast major spore episodes of this pathogen when weather & Hirst spore trap data collected in a commercial onion field in Orange Cty, NY were used to evaluate the models. The sporulation index model for B. squamosa forecasted only 51.2% of the minor spore episodes (daily mean 1.0-9.9 spores/m3 air) and 58.7% of the major spore episodes (mean > 10 spores/m3) in a 7 yr data set. The DINOV submodel of the BOTCAST predictive system for B. squamosa forecasted 81.8% of the minor spore episodes but only 56.5% of the major spore episodes in a 2 yr data set in which all appropriate weather data were available. An alternative model was developed by deriving a set of decision rules (modifications from BOTCAST) & regression equations that identified conditions associated with the occurrence or non-occurrence of significant spore episodes.
Temperature, relative humidity, and calendar date were used as variables in the model, which was designed to issue a daily forecast--the Inoculum Production Index (IPI)--for the presence or absence of significant sporulation. The IPI model correctly forecasted 66.7% of the minor spore episodes & 94.2% of the major spore episodes in the 7 yr data (Orange Cty data) used to develop the model. Similar results were obtained with a 4 yr data set not used in model development (76.2 & 88.6% of minor and major spore episodes, respectively).
Impacts
(N/A)
Publications
- AWUAH, R. T. and LORBEER, J. W. 1988. Nature of cultural variability in Fusarium oxysporum f. sp. apii race 2. Phytopathology 78:385-389.
- LORBEER, J. W. and DEMILIA, M. S. 1988. Spray trials for the control of Botrytis leaf blight of onion conducted during 1988 in New York. Cornell Univ, Agr & Life Sci, Ithaca, NY. 7 pp.
- RIST, D. L. and LORBEER, J. W. 1987. Weed reservoirs of cucumber mosaic virus (CMV) and BBWV diseases of commercial lettuce. Phytopathology 77:1618. (abstract).
- SHISHKOFF, N. and LORBEER, J. W. 1987. A new leaf disease of onion in New York caused by Stemphylium vesicarium. Phytopathology 77:1713. (Abstract).
- VINCELLI, P. C. and LORBEER, J. W. 1987. Relationship of precipitation probability to infection potential of Botrytis squamosa on onion. Phytopathology 77:1620. (abstract).
- VINCELLI, P. C. and LORBEER, J. W. 1988. Comparison of predictive systems for timing the initial fungicide application to control Botrytis leaf blight of onion. Plant Disease 72:632-635.
- VINCELLI, P. C. and LORBEER, J. W. 1988. Forecasting spore episodes of Botrytis squamosa in commercial onion fields in New York. Phytopathology 78:966-970.
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