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 6.5.1 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 fungicides for soybean disease control based on appropriate application timing*
Fungicides Aerial web blight Anthacnose Brown spot Cercospora leaf blight 2 Frogeye leaf spot 3 Pod and stem blight Soybean rust White mold 4 Harvest restriction 5
Class Active ingredient (%) Product/Trade name Rate/A (fl oz)
QoI Strobilurins Group 11 Azoxystrobin 22.9% Quadris 2.08 SC 6.0-15.5 VG VG G F P -6 G-VG P Grain: 14 days; forage/hay: 0 days
Fluoastrobin 40.3% Evito 480 SC 2.0-5.7 VG G G F P -6 -6 NL R5 (beginning seed); forage: 3 days; seed: 30 days
Picoxystrobin *^Approach 2.08 SC 6.0-12.0 VG G G F P -6 G G 14 days
Pyraclostrobin 23.6% Headline 2.09 EC/SC 6.0-12.0 VG VG G F P -6 VG NL 21 days
DMI Triazoles Group 3 Cyproconazole 8.9% Alto 100SL 2.75-5.5 -6 -6 VG F6 F -6 VG NL 30 days
Flutriafol 11.8% Topguard 1.04 SC7 7.0-14.0 -6 VG VG F VG -6 VG-E F 21 days
Propiconazole 41.8% Tilt 3.6 EC Multiple Generics 2.0-4.0 P VG G NL F NL VG NL R5 (beginning seed)
Prothioconazole 41.0% Proline 480 SC 8 3.0-5.0-5.7 NL NL NL NL G-VG NL VG F 21 days
Tetraconazole 20.5% Domark 230 ME Multiple Generics 4.0-5.0 NL VG VG F G -6 VG-E F R5 (beginning seed)
MBC Thiophanates Thiophanate-methyl Topsin-M Multiple Generics 10.0-20.0 -6 -6 -6 F VG -6 G F 21 days
SDH1 Carboximides Group 7 Boscalid 70% Endura 0.7 DF 3.5-11.0 -6 NL VG -6 P NL NL VG 21 days
Mixed Mode of Action azoxystrobin 18.2% difenconazole 11.4% Quadris Top 2.72 8.0-14.0 -6 -6 -6 -6 VG -6 VG NL 14 days
azoxystrobin 7.0% propiconazole 11.7% Avaris 1.66 SC Quilt 1.66 SC 14.0-20.5 -6 -6 G -6 F -6 VG NL R6
azoxystrobin 13.5% propiconazole 11.7% Quilt Xcel 2.2 SE 10.5-21.0 E VG G F F -6 VG NL R6
cyproconazole 7.17% picoxystrobin 17.94% *┬žAproach Prima 2.34 SC 7,12 5.0-6.8 -6 -6 -6 -6 G -6 -6 NL Grain: 30 days; forage/hay: 14 days
puraclostrobin 28.58% fluxapyroxad 14.33% *┬žPriaxor 4.17 SC 7,12 4.0-8.0 E VG E F F -6 VG P 21 days
tetraconazole 7.48% azoxystrobin 9.35%td> Affiance SC 10.0-14.0 -6 -6 -6 -6 -6 -6 -6 -6 14 days
trifloxystrobin 32.3% prothioconazole 10.8% Stratego YLD 4.18 SC 9,10 4.0-4.65 VG VG VG F F -6 VG NL 21 days
* This information was adapted for New York by Gary C. Bergstrom, Cornell University, from information developed by the North Central Regional Committee on Soybean Diseases and the Regional Committee for Soybean Rust Pathology (NCERA-212 and NCERA-208) 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 gungicide 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 location. The table is not intended to be a list of all labeled products 2 Efficacy categories: NR=Not Recommended; P=Poor; F=Fair; G=Good; VG=Very Good; E=Excellent; NL=Not Labeled for use against this disease. Many products have specific use restrictions about the among of active ingredient that can be applied within a period of time or the among of sequential applications that can occur. Please read and folloe 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 in theis publication 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 NVERA-212 or NCERA-208 group assume no liability resulting from the use of these products.
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 populationthat 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.
8Proline has a supplemental label (2ee) for soybean, only for use on white mold in IL, IN, IA, MI, MN, NE, ND, OH, SD, WI. A separate 2ee for New York exists for white mold.
9Stratego YLD has a supplemental label (2ee) for white mold on soybean, only in IL, IN, IA, MI, MN, NE, ND, OH, SD, WI, but not in New York.
10Aerial application is not allowed in New York.
11No application is allowed withing 100 feet of coastal marsh.
12No application is allowed withing 100 feet of aquatic habitats.