Progress 09/15/03 to 09/14/06
Outputs
Fungicides were tested yearly for foliar blight control in 4 greenhouse and 15 field trials. Field trials, in grower-cooperators' gardens in Wausau, WI, were featured during annual Research Field Days. Industry standards (chlorothalonil, mancozeb, B2 carcinogens, available only through Section 18 Specific Exemption labels) were compared to 29 others, including newer (boscalid, pyraclostrobin/boscalid), reduced-risk (azoxystrobin, fenhexamid, fluazinam, fludioxonil, pyraclostrobin, pyrimethanil, cyprodinil/fludioxonil, trifloxystrobin) and biopesticide products (Bacillus subtilis, harpin protein, phosphorous acid salts, polyoxin D zinc salt, Trichoderma harzianum). Results supported the registration of fenhexamid and polyoxin D zinc salt as non-food use pesticides against Botrytis blight. Fluazinam was especially helpful for foliar blight; our data supported fluazinam as a priority for registration through the IR-4 and a full-use label is anticipated within 12-18
months. Root rots have proved to be a problem for ginseng growers and are exacerbated by uncontrolled foliar blight; 16 trials evaluated 35 products, including 9 reduced-risk and 4 biopesticides, for control of disease caused by Phytophthora cactorum, Cylindrocarpon destructans, Fusarium sp. and Rhizoctonia solani. Mancozeb/zoxamide (available through a Section 18 Specific Exemption label), captan, flutolanil and reduced-risk fungicides, fludioxonil and fenamidone, have proved effective at limiting root rots. The TOM-CAST forecaster alerts growers to apply sprays when conditions favor disease spread, and calculates a daily disease severity value (DSV) of 0 (no disease) to 4 (disease) by using the time leaves are wet and average air temperature during the wetness periods (collected by a weather sensor). 3 years of research compared 3 fungicide programs (chlorothalonil alone, pyraclostrobin alternated with chlorothalonil or copper hydroxide) applied according to 7-day, 10-day, 10-DSV
and 15-DSV schedules. Although cold nights affected the 2004 trial, all schedules significantly reduced foliar blight in 2005-06 compared to the untreated. 7-day sprays were applied 16 times in 2005 and in 2006, while 10-DSV scheduled 10 and 7 sprays, and 15-DSV scheduled 6 and 5 sprays in 2005 and 2006, respectively. A spore trap, placed in a field where Alternaria blight caused significant plant death in 2004-06, evaluated weather effects on Alternaria spore production. 2006 spores are being counted. Within each 24-hour period in 2004-05, hourly atmospheric conidial concentrations were greatest during periods of rapidly decreasing relative humidity. Peak concentrations were seen following rain, and were especially high following periods with high weekly rainfall totals. Conidial concentrations and temperatures were higher in 2005 than 2004; temperatures >25C were 35.1 and 11.8 hours/week, respectively. Current cultural methods (growing under shade, overhead watering) increase
relative humidity and plant wetness and decrease air movement; favoring foliar disease. Changing the ginseng microenvironment may decrease disease occurrence; one grower has placed drip irrigation in his commercial garden.
Impacts
Replacing or rotating carcinogenic fungicides with effective reduced-risk or biopesticide products can decrease the exposure of humans and the environment to harmful products while maintaining quality and yield of the ginseng crop. Research indicates that alternating chlorothalonil (B2 carcinogen) and pyraclostrobin (reduced-risk) appears promising for foliar blight control, while decreasing the amount of harmful fungicides applied to ginseng up to 50%. Further reduction can occur by replacing harmful fungicides with other effective reduced-risk (fenhexamid, fluazinam) and biopesticide (polyoxin D zinc salt) products. Disease forecasters are computer programs that use weather information combined with how disease epidemics develop to alert growers to apply fungicide sprays only when needed. By optimizing fungicide sprays, growers typically make fewer total applications. Research has shown that the TOM-CAST disease forecaster may be a useful tool for ginseng growers.
Using TOM-CAST 10 DSVs reduced the sprays needed to control foliar blights to 10 in 2005 and 7 in 2006 (a reduction of 38% and 56% of the sprays, respectively) compared to 7-day applications. When applying chlorothalonil, this would result in a fungicide savings of $59/A and $89/A for 2005 and 2006, respectively. Effective disease management programs that combine all these techniques can reduce the number of fungicide sprays, growers' costs, pesticide residues on the produce, environmental contamination, and risk of development of pesticide resistance in the fungi.
Publications
- Hill, S.N., Hausbeck, M.K. 2006. Influence of environment on atmospheric concentrations of Alternaria panax conidia in cultivated American ginseng gardens. (Abstr.) Phytopathology 96:S48.
- Hausbeck, M.K., Harlan, B.R. 2006. Effectiveness of labeled fungicides for the control of foliar diseases on ginseng, 2005. Fungicide and Nematicide Tests 61:V141.
- Hausbeck, M.K., Harlan, B.R. 2006. Evaluation of TOM-CAST and fungicide programs for managing Alternaria blight of ginseng, 2005. Fungicide and Nematicide Tests 61:V142.
- Hausbeck, M.K., Harlan, B.R. 2006. Effectiveness of fungicides and the biopesticide Endorse 11.3DF to control Alternaria blight on ginseng, 2005. Fungicide and Nematicide Tests 61:V143.
- Webster, B.J., Hausbeck, M.K. 2006. Evaluation of reduced-risk fungicides and biopesticides for control of Alternaria blight of ginseng, 2005. Fungicide and Nematicide Tests 61:V065.
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Progress 01/01/05 to 12/31/05
Outputs
Four Wisconsin field and 2 Michigan greenhouse trials tested 63 treatments of 16 products used alone and in alternation/combination for control of foliar blights of ginseng, including Alternaria and Botrytis blights and powdery mildew. Untreated plants received an Alternaria blight severity rating of 4-10 (1=healthy, 10=dead). Products that proved significantly effective at reducing Alternaria (rating=1-3) included a biopesticide (Endorse); reduced-risk fungicides (Amistar 80WG, Cabrio EG, Omega 500F); other products (Bravo Weather Stik 6SC, Dithane 75DF, Kocide 2000 DF); and alternations of Dithane with Phostrol (biopesticide); Cabrio with Kocide, Bravo or Endorse; Endorse with Dithane or Bravo; and Dithane/Endorse/Cabrio/Bravo. Severity of Botrytis blight on untreated plants was 5.8-6.8. Fungicides that limited Botrytis (rating=1.3-2.8) included reduced-risk fungicides (Elevate 50WDG, Omega, Amistar) and other products (Bravo, Dithane, Endura 70WG, Kocide). Powdery
mildew was controlled (rating=1.8-3.0) by Amistar, Bravo, Dithane, Kocide and alternations of Dithane/Phostrol, while untreated plants had a 6.8 severity rating. The 2nd year of a Wisconsin field trial compared sprays of Bravo Weather Stik, and Bravo or Kocide alternated with Cabrio applied according to TOM-CAST 10- and 15-DSV and at 7- and 10-day intervals; numbers of sprays were 10, 6, 16 and 10, respectively. Untreated controls averaged 60.3 Alternaria-infected plants with a severity of 4.3. All treatments completely prevented Alternaria infection, except for Kocide alternate Cabrio applied at 10-day intervals. This treatment was better than the untreated controls, averaging 0.5 infected plants per 10 ft with a severity rating of 1.3. Spores of Alternaria panax were sampled from Wisconsin ginseng gardens for a 2nd year. Correlation of spore numbers with weather data to detect environmental influences on the occurrence of Alternaria blight is ongoing. Seed pathology research has
found the following pathogens present on ginseng seed: Alternaria panax, Alternaria alternata, Cylindrocarpon destructans, Fusarium sp., Phytophthora cactorum, Pythium sp. Preliminary research is investigating treatments that reduce seed-borne pathogen infection while preserving or enhancing germination rate. The identification of Alternaria spp. on the ginseng seed as a contaminant is an important finding. Addressing seed contamination could further reduce needed fungicide sprays by reducing initial inoculum. Drip irrigation technology was investigated in a ginseng research garden established at the Plant Pathology farm at Michigan State University. Similar technology is being tested on a 3-acre commercial ginseng garden in Wausau, WI. Field trials described were conducted in commercial ginseng gardens with grower cooperators. A field day was held in the Wausau, WI area during August with approximately 50 growers and industry personnel present. An in-depth grower workshop and meeting
were held in March to convey research results. Approximately 70 growers were in attendance.
Impacts
Wisconsin and Michigan provide 90% of the cultivated ginseng in the U.S. and 10% of the supply for the world. Many fungicides are restricted to a maximum number of applications per season. Fungicide resistance in the pathogen can be a concern. Growers need products with different modes of action to produce healthy plants. Effective alternative, reduced-risk and biopesticide products identified by this research that are labeled can be used in rotation with industry standards to reduce the amounts of B2 carcinogenic fungicides applied to ginseng gardens by up to 50% without compromising disease control. Use of the TOM-CAST disease forecaster can further reduce fungicide applications. During 2005, 10 and 6 sprays were saved compared to 7- and 10-day programs (16 sprays) without compromising Alternaria blight control, a 62.5% and 37.5% savings in fungicide applications, respectively. The identification of Alternaria spp. in association with ginseng seed indicates that
seed treatments are needed to reduce initial inoculum. Reducing initial inoculum through seed treatment will prevent the introduction of the Alternaria pathogen to new plantings and reduce the need for fungicides. As a result of this research, the biopesticide Endorse will be labeled for ginseng as a non-food use. The development of efficacy data has supported the prioritization of Moncut 70DF, Omega 500F, Cannonball 50WP, Captan 80WDG, Acrobat 50WP, and Gavel 75DF for residue studies in the IR-4 program. Once the residue studies are complete, data from our research will be used to develop the product labels.
Publications
- Hausbeck M.K., Harlan, B.R. 2005. Effectiveness of fungicides and the biopesticide Endorse 2.5WP to control Alternaria blight on ginseng, 2004. Fungicide and Nematicide Tests 60:V019.
- Hausbeck M.K., Harlan, B.R. 2005. Effectiveness of fungicides and the biopesticide Endorse 2.5WP to control Botrytis blight on ginseng, 2004. Fungicide and Nematicide Tests 60:V020.
- Hausbeck M.K., Harlan, B.R. 2005. Effectiveness of registered and unregistered fungicides to control Alternaria blight on ginseng, 2004. Fungicide and Nematicide Tests 60:V021.
- Hausbeck M.K., Harlan, B.R. 2005. Effectiveness of registered and unregistered fungicides to control Botrytis blight on ginseng, 2004. Fungicide and Nematicide Tests 60:V022.
- Hausbeck M.K., Harlan, B.R. 2005. Evaluation of TOM-CAST and fungicide programs for managing Alternaria blight of ginseng, 2004. Fungicide and Nematicide Tests 60:V023.
- Hill, S., Hausbeck, M. 2005. Detection of Phytophthora cactorum on ginseng seed and screening pathogen isolates for resistance to mefenoxam. Phytopathology 95:S42.
- Webster, B.J. 2005. Managing foliar blights on specialty crops. M.S. Thesis. Michigan State University, E. Lansing.
- Webster, B.J., Hausbeck, M.K. 2005. Evaluation of reduced risk fungicides and biopesticides for control of Botrytis blight of ginseng, 2004. Fungicide and Nematicide Tests 60:V060.
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Progress 01/01/04 to 12/31/04
Outputs
http://www.ipmcenters.org/pmsp/pdf/MIWIginseng.pdf. One greenhouse and 2 WI field trials each for Alternaria and Botrytis tested 68 treatments for foliar blight control. Included were reduced risk fungicides (Cabrio, Elevate, Endura, Flint, Omega, Pristine, Quadris, Scholar, Switch), biopesticides (Endorse, Messenger, PlantShield, Serenade), plant activator (Actigard) and industry standards/others (Bravo Weather Stik, Dithane, Iprodione, Scala, Topsin). All treatments significantly decreased Alternaria-infected plants compared to the untreated controls. Endorse and Quadris showed the least amount of disease; Topsin was less effective than the other treatments. Botrytis was significantly decreased by all treatments except Dithane (in one trial) when compared to the controls; standout products included Endorse, Endura and Pristine. A WI field trial compared sprays of Bravo Weather Stik, and Bravo or Kocide alternated with Cabrio applied according to TOM-CAST 10- or
15-DSV and at 7- and 10-day intervals. Night temperatures were cool; disease developed late but was severe. Numbers of sprays were 15, 10, 2 and 1 for 7-day, 10-day, 10-DSV and 15-DSV, respectively. Untreated controls averaged 175.5 infected and 50.8 defoliated plants. All programs prevented defoliation. Although all programs significantly reduced disease compared to the untreated, TOM-CAST did not meet grower standards for crop quality. Adjustments to TOM-CAST applications may be needed for extended periods of cool weather. Two spore samplers were placed in WI fields. Slides from the 2004 growing season are currently being examined for presence of Alternaria spores. Once counted, spore numbers will be correlated with weather data to detect environmental influences on the occurrence of Alternaria blight. OTHER RESEARCH: Diseased ginseng samples yielded 101 Phytophthora cactorum isolates in 2004; 94 were insensitive and 7 were sensitive to mefenoxam, demonstrating a need for
alternative fungicides to control this disease. Nine greenhouse trials tested 118 treatments for control of root rots of ginseng. Products included reduced risk fungicides (Amistar, Cabrio, Pristine, Quadris, Ranman, Reason, Ridomil Gold, Scholar, Zoxamide), biopesticides (Companion, Endorse, Phostrol, PlantShield), and industry standards and others (Acrobat, Aliette, Bravo Weather Stik, Captan, Curzate, Dithane, Gavel, Kocide, Moncut, Previcur Flex, Tanos, Terraguard, Terramaster, Topsin, experimentals). Topsin, Captan and Scholar proved effective against disease caused by Cylindrocarpon destructans. Disease caused by P. cactorum was effectively managed by Captan, Curzate and Kocide. Endorse, Moncut and Scholar controlled Rhizoctonia root rot, while Topsin proved ineffective. A fumigant trial evaluated six treatments for control of Cylindrocarpon and Fusarium root rots and northern root-knot nematode on ginseng. Plant vigor was not affected, but untreated plants had significantly
shorter roots and more severe nematode infection. Methyl bromide/chloropicrin and Telone C35 prevented nematode nematode gall formation.
Impacts
Reducing the amount of carcinogenic or other potentially harmful pesticides applied to ginseng crops is the goal of U.S. ginseng growers. The indentification of the biopesticide Endorse 2.5WP as an effective product is important and may lead to a non-food use label. The field demonstrations were viewed by the growers during a field meeting and findings of new management techniques will be implemented.
Publications
- Hausbeck, M.K., preparer. 2004. Pest management in the future, a strategic plan for the Michigan and Wisconsin ginseng industry. USDA Regional Pest Management Centers, Crop Profiles/PMSP. Online.
- Hausbeck, M.K., Harlan, B.R. 2004. Evaluation of the biopesticide Endorse to control Botrytis blight on ginseng, 2003. Fungicide and Nematicide Tests 59:V059. Online.
- Hausbeck, M.K., Harlan, B.R., Peever, M.J., Heil, J. 2004. Evaluation of the biopesticide Endorse to control Alternaria blight on ginseng, 2003. Fungicide and Nematicide Tests 59:V049. Online.
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Progress 01/01/03 to 12/31/03
Outputs
http://plantpathology.msu.edu/labs/hausbeck/hausbeckResearch.htm. Ginseng is a high value commodity for Wisconsin and Michigan with an estimated worth of more than $100 million. These states provide 90% of the cultivated ginseng in the USA and 10% of the world's supply. Management tools are needed to control fungal diseases of ginseng and insure the sustainability of this crop. OBJECTIVE 1: Identify effective alternatives to fungicides critical to ginseng production (mancozeb and chlorothalonil, classified as B2 carcinogens) by testing biopesticides, biocontrol agents, induced resistance products, and reduced risk or soft pesticides for control of Alternaria and Botrytis foliar blights. Two trials tested Dithane 75DF (industry standard, mancozeb), Quadris 2.08SC (azoxystrobin, reduced risk fungicide) and Endorse 2.5WP (polyoxin D zinc salt, biopesticide) for control of ginseng foliar blights. Alternaria blight in a field trial was severe, and Quadris 2.08SC was the
only treatment that significantly reduced incidence of stem infection (34.6%) when compared with the untreated plants (77.1%). Incidence of petiole infection was less than 20.0% on plants treated with Quadris, and Endorse 2.5WP (1.1 and 1.6 lb) alternated with Quadris. Applications of Quadris and Endorse alternated with Dithane 75DF limited severity of stem infection to 2.7 and petiole infection to 2.0 (1 = no lesions, 10 = girdled). A greenhouse trial tested products for managing Botrytis blight. Plants treated with Endorse had no Botrytis lesions at the end of this study. When infection was summarized over time by evaluating disease under the progress curve, Endorse (1.1 and 1.6 lb) was significantly better than Quadris at limiting disease. These trials identified two potential alternatives to the industry standard, a B2 carcinogen, for managing foliar blights of ginseng. OBJECTIVE 2: Reduce reliance on fungicides categorized as B2 carcinogens by establishing spray thresholds and
using a disease forecaster with reduced risk fungicides, or other effective alternatives for Botrytis and Alternaria foliar blights. A WatchDog weather station was placed in a grower cooperator's field in Marathon County, WI from July to October. It recorded temperature, relative humidity, leaf wetness and rainfall. This data will be used to choose a disease forecasting program to be used in next year's trials. The disease forecaster will be compared to a calendar-based spray program and evaluated for quality of disease control and amount of pesticide applied per acre. OTHER RESEARCH: Diseased ginseng samples from Michigan and Wisconsin were found to be infected with Phytophthora cactorum. Of the 114 isolates of P. cactorum tested in vitro on V8 agar plates amended with 100 ppm mefenoxam, 87 were insensitive and 27 were sensitive to the fungicide. This demonstrates a need for research to identify alternative fungicides for managing Phytophthora disease which can be used when mefenoxam
is ineffective.
Impacts
Reducing the amount of carcinogenic or otherwise harmful fungicides applied to ginseng crops would be beneficial to the environment and human health. Treatments of Quadris 2.08SC and Endorse 2.5WP alternated with Dithane 75DF (mancozeb, a B2 carcinogen) limited the severity of stem and petiole infection due to Alternaria blight in 2003. Due to resistance concerns, it is recommended that Quadris be alternated with another fungicide; therefore alternating Quadris or Endorse with the industry standard Dithane would reduce mancozeb use by 50% and prevent 7.5 lb/A of mancozeb being applied to ginseng fields in a growing season similar to 2003.
Publications
- No publications reported this period
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