Diseases of Soybeans

Several diseases, including Phytophthora root and stem rot, pod and stem blight, frogeye leaf spot, brown spot, downy mildew, Cercopsora leaf blight and purple seed stain, and Sclerotinia stem rot (white mold), are known to affect soybeans in New York. Little is known, however, about the incidence, severity, or yield effects of diseases in the state. Diseases generally are kept in check by the use of sound agronomic practices such as crop rotation and the selection of soybean varieties with resistance to diseases known to be a problem in the local area. Although there is little research information on which to base chemical disease control guidelines in New York, the following information on fungicides is included as a service to New York growers who may wish to apply fungicides.

Disease Management

Fungicidal Seed Treatment

Treatment of seed with protectant fungicides, professionally applied by the seed supplier, is recommended for all soybean seed planted in New York - with the exception of organic production. Fungicide treatment is especially needed when seeds are planted into cold wet soils or where there is a field history of damping-off or Phytophthora root rot. Planting of bin-run seed is discouraged, though planter box application of fungicide can be made by the grower at the time of seeding. Remember to read and follow pesticide labels carefully.

Foliar Fungicides

Several fungicide products are registered for use on soybeans by foliar application. The efficacy of these products for soybean disease control based on appropriate application timing and labeled rates is listed in Table 6.5.2 as a convenience for New York soybean producers. While each of the diseases listed occurs in the state, the data on the relationships between disease severity, yield loss, and economic return are not sufficient to base a recommendation for fungicide application to soybeans in New York. Good data from other parts of the United States, however, indicate that foliar fungicide application to a soybean seed crop (where environmental conditions and local disease pressure warrant it) can substantially increase seed vigor and germinability and can reduce the carryover of inoculum of seedborne diseases such as pod and stem blight and anthracnose.

Table 6.5.1

Table 6.5.1. Efficacy of seed-applied fungicides for control of soybean seedling diseases*

Fungicide active ingredientPythium sp.1Phytophthora sp.Rhizoctonia sp.Fusarium sp.1,3Sudden death syndrome (SDS)
(Fusarium virguliforme)
Phomopsis sp.

*The members of North Central Regional Committee on Soybean Diseases (NCERA-137) have developed the following ratings for how well fungicide seed treatments control seedling diseases of soybeans in the United States. Efficacy ratings for each fungicide active ingredient listed in the table were determined by field-testing the materials over multiple years and locations by the members of this group, and include ratings summarized from national fungicide trials published in Plant Disease Management Reports (and formerly Fungicide and Nematicide Tests) by the American Phytopathological Society at http://www.apsnet.org. Each rating is based on the fungicide’s level of disease control, and does not necessarily reflect efficacy of fungicide active ingredient combinations and/or yield increases obtained from applying the active ingredient.

The list includes ingredients in the most widely marketed products available as of the release date of the table. It is not intended to be a list of all labeled active ingredients. Additional active ingredients may be available but have not been evaluated in a manner allowing a rating. Many active ingredients and their products have specific use restrictions. Read and follow all use restrictions before applying any fungicide to seed, or before handling any fungicide-treated seed. This information is provided only as a guide. It is the applicator’s and users’ legal responsibility to read and follow all current label directions. Reference in this publication to any specific commercial product, process, or service, or the use of any trade, firm, or corporation name is for general informational purposes only and does not constitute an endorsement, recommendation, or certification of any kind by members of the group, or by the North Central Soybean Research Program. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer. Efficacy categories: E = Excellent; VG = Very Good; G = Good; F = Fair; P = Poor; NR = Not Recommended; NS = Not Specified on product label; U = Unknown efficacy or insufficient data to rank product.

Ratings of NR may mean that the fungal group listed is not a target of the specific fungicide active ingredient.

Please note: Efficacy ratings may be dependent on the rate of the fungicide product on seed. A number of different species of Pythium and Fusarium impact seed and seedling health in soybean. Therefore, wide ranges in efficacy may be observed in fungicide active ingredients listed in the table. Therefore several fungicide active ingredients are combined in seed treatments to provide protection to a broader spectrum of pathogens.

1Products may vary in efficacy against different Fusarium and Pythium species.

2Areas with mefenoxam or metalaxyl insensitive populations may see less efficacy with these products.

3Listed seed treatments do not have efficacy against Fusarium virguliforme, causal agent of sudden death syndrome.



Table 6.5.2

Table 6.5.2 Efficacy of fungicides for soybean disease control based on appropriate application timinga
FungicidesAnthacnoseBrown spotCercospora leaf blight2Frogeye leaf spot3Pod and stem blightSoybean rustWhite mold4Harvest restriction5
ClassActive ingredient (%)Product/Trade nameRate/A (fl oz)
QoI Strobilurins Group 11Azoxystrobin 22.9%Quadris 2.08 SC6.0-15.5VGP-GPPU6G-VGP14 days
Fluoastrobin 40.3%Evito 480 SC8,102.0-5.7GP-GPPUUNLR5 (beginning seed) 30 days
PicoxystrobinApproach 2.08 SC106.0-12.0GP-GPPUGG14 days
Pyraclostrobin 23.6%Headline 2.09 EC/SC106.0-12.0VGP-GPPUVGNL21 days
DMI Triazoles Group 3Cyproconazole 8.9%Alto 100SL2.75-5.5UVGFFUVGNL30 days
Flutriafol 11.8%Topguard 1.04 SC77.0-14.0UVGP-GG-VGUVG-EF21 days
Propiconazole 41.8%Tilt 3.6 EC Generics4.0-6.0VGGNLFNLVGNLR5 (beginning seed)
Prothioconazole 41.0%Proline 480 SC2.5-5.0NLNLNLG-VGNLVGF21 days
Tetraconazole 20.5%Domark 230 ME4.0-5.0VGVGP-GF-GUVG-EFR5 (beginning seed)
MBC Thiophanates Group 1Thiophanate-methylTopsin-M Generics10.0-20.0UUFVGUGF21 days
2,6-Dinitro-anilines Group 29fluazinam 40%*Omega 500 DF8,100.75-1.0 pintsNLNLNLNLNLNLGR3 (beginning pod)
SDHI Carboximides Group 7Boscalid 70%Endura 0.7 DF3.5-11.0NLVGUPNLNLVG21 days
azoxystrobin 25.3%
difenoconazole 18.63%
Topguard EQ 4.29SC75.0-7.0UVGUG-VGUEU21 days
Mixed Mode of Actionazoxystrobin 18.2% difenconazole 11.4%Quadris Top 2.72 SC8.0-14.0UG-VGP-GVGF-GVGNL14 days
azoxystrobin 7.0% propiconazole 11.7%Avaris 1.66 SC14.0-20.5UGFFUVGNL21 days
azoxystrobin 13.5% propiconazole 11.7%Quilt Xcel 2.2 SE10.5-21.0VGGFFUVGNLR6
benzovindiflupyr 2.9%
azoxystrobin 10.5%
propiconazole 11.9%
Trivapro SE813.7-20.7UG-VGP-GF-GGVG-ENLR6 or 14 days
cyproconazole 7.17%
picoxystrobin 17.94%
Aproach Prima 2.34 SC105.0-6.8UGP-GF-GUVG-ENL14 days
fluopyram 17.4%
prothioconazole 17.4%
*Propulse 3.34 SC76.0-10.2NLUNLUUUG21 days
flutraiafol 19.3%
fluoxastrobin 14.84%
*Fortix SC7,8,94.0-6.0UG-VGP-GG-VGUUUR5
prothioconazole 16.0%
trifloystrobin 13.7%

Delaro 325 SC3, 8

8.0-11.0UVGUG-VGUUNL21 days
pydiflumetofen 7.0%
azoxystrobin 9.3%
propiconazole 11.6%
*Miravis Neo13.7-20.8UUUVGUUUR6 or 14 days
pydiflumetofen 13.7%
difenoconazole 11.5%
*Miravis Top 1.67 SC13.7UVGF-GVGGVG-EU14 days
pyraclostrobin 28.58%
fluxapyroxad 14.33%
*Priaxor 4.17 SC 7,104.0-8.0VGG-VGP-GP-FUVG-EP21 days
trifloxystrobin 32.3%
prothioconazole 10.8%
Stratego YLD 4.18 SC84.0-4.65VGGFF-GUVGNL21 days
tetraconazole 7.48%
azoxystrobin 9.35%
Affiance SC10.0-14.0UVGVGF-GUUUR5 or 14 days
tetraconazol 17.76%
fluoxastrobin 17.76%
*Zolera FX 3.34 SC7,8,94.4-6.8UUUF-GUUUR5 or 30 days
thiophanate-methyl 21.3%
tetraconazole 4.2%
mefentrifluconazole 11.61%
pyraclostrobin 15.49%
fluxapyroxad 7.74%
Revytek108.0-15.0UVGF-VGVGUVG-EP21 days

aThis information was adapted for New York by Gary C. Bergstrom, Cornell University, from information developed by the North Central Regional Committee (NCERA-137) on foliar fungicide efficacy for control of major foliar soybean diseases in the United States. Efficacy ratings for each fungicide listed in the table were determined by field-testing the materials over multiple years and locations by the members of the committee. Efficacy ratings are based upon level of disease control achieved by product and are not necessarily reflective of yield increases obtained from product application. Efficacy depends upon proper application timing, rate, and application method to achieve optimum effectiveness of the fungicide as determined by labeled instructions and overall level of disease in the field at the time of application. Differences in efficacy among fungicide products were determined by direct comparisons among products in field tests and are based on a single application of the labeled rate as listed in the table, unless otherwise noted. Table includes fungicides available that have been tested over multiple years and locations. The table is not intended to be a list of all labeled products1. Efficacy categories: P=Poor; F=Fair; G=Good; VG=Very Good; E=Excellent; NL=Not Labeled for use against this disease; U=Unknown efficacy or insufficient data to rank product. Many products have specific use restrictions about the among of active ingredient that can be applied within a period of time or the amount of sequential applications that can occur. Please read and follow all specific use restrictions prior to fungicide use. This information is provided only as a guide. It is the responsibility of the pesticide applicator by law to read and follow all current label directions. Reference to products on this website is not intended to be an endorsement to the exclusion of others that may be similar. Persons using such products assume responsibility for their use in accordance with current directions of the manufacturer. Members of participants in the NCERA-212 or NCERA-208 group assume no liability resulting from the use of these products.
*Restricted-use pesticide.
1 Some fungicides not in this table may be labeled for soybean rust only, powdery mildew, and Alternaria leaf spot. Contact fungicides such as chlorothalonil may also be labeled for use.
2 Cercospora leaf blight efficacy relies on accurate application timing, and standard R3 application timings may not provide adequate disease control. Fungicide efficacy may improve with later applications.
3Fungicides with a solo or mixed QoI mode of action may not be effective in areas where QoI-resistance has been detected in the fungal population that causes frogeye leaf spot. In areas such as New York where QoI-fungicide resistant isolates of the frogeye leaf spot pathogen have not been detected, QoI fungicides may be more effective than indicated in this table.
4 White mold efficacy is based on an R1 application timing, and lower efficacy is obtained at an R3 application timing, or if disease symptoms are already present at the time of application.
5Harvest restrictions are listed for soybean harvested for grain. Restrictions may vary for other types of soybean (edamame, etc.) and soybean for other uses such as forage or fodder.
6Insufficient data is available at this time to make statements about efficacy of these products for diseases listed in the table.
7No sale, use, or distribution in Nassau or Suffolk Counties in New York.
8Aerial application is not allowed in New York.
9No application is allowed withing 100 feet of coastal marsh.
10No application is allowed withing 100 feet of aquatic habitats.