MISSISSIPPI SOYBEAN PROMOTION BOARD PROJECT NO Annual Report. Title: Soybean disease monitoring for Mississippi soybean producers

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1 MISSISSIPPI SOYBEAN PROMOTION BOARD PROJECT NO Annual Report Title: Soybean disease monitoring for Mississippi soybean producers Project Leader: Tom Allen, EXECUTIVE SUMMARY Sentinel plots were planted throughout MS and were monitored for early detection of soybean rust and other foliar diseases. Even though rust was detected in all 82 MS counties, yield losses were minimal. In addition to scouting sentinel plots on an almost weekly basis from April through September (or when they reached R8 or physiological maturity), a total of 475 commercial soybean fields throughout the state as well as 367 kudzu patches were monitored during 2012 for the presence of numerous, economically important diseases and nematodes. If and when issues were observed, the information was reported to the state s producers so that remedial measures could be selected and applied. Soybean leaf samples from fields infected with frogeye leaf spot (FLS) were submitted to be tested for the presence of strobilurin-resistant strains of the causal organism, Cercospora sojina. Strobilurin and triazole fungicides, and their pre-mixes, did not reduce symptoms of Cercospora blight regardless of their application timing. BACKGROUND AND OBJECTIVES Numerous yield-limiting disease issues plague farmers throughout MS on an annual basis. Since 2005, soybean rust has been one of the most closely monitored diseases throughout the soybean producing area. Mississippi has cooperated at the regional and national level in monitoring for soybean rust by planting early-planted soybean plots, termed sentinel plots, to monitor for the presence of soybean rust. The information gained from these plots is used to provide farmers with management alternatives to avoid yield losses as a result of soybean rust infestation, or losing money by making an ill-timed fungicide application when the disease is not threatening. The main objective of the soybean disease monitoring project is to determine where important yield-limiting diseases are occurring (inclusive of soybean rust), and then disseminate this pertinent information using several different media sources so that farmers are aware of a potential threat as a result of foliar diseases. Throughout the 2012 season, Billy Moore, Andy Milling, Mike Steede, and Tom Allen scouted for soybean diseases throughout the state in commercial soybean fields as well as the 21 sentinel plots that were planted in counties along the edges of the state to serve as an early warning system for important diseases.

2 PROGRESS/ACTIVITY Objective 1. Monitor for foliar soybean diseases throughout MS to provide soybean farmers the necessary information to make informed, timely decisions regarding fungicide application(s) as well as product choices (either strobilurin or triazole) depending on the specific disease(s) present in commercial fields. Soybean diseases were monitored throughout the 2012 season by observing sentinel plots that consisted of MG III, IV, V, and VII varieties so that reproductive growth stages were present prior to those of the commercially planted soybean crop. Thus, important diseases such as soybean rust would likely be observed in the sentinel plots prior to making an appearance in commercial soybean fields. In 2012, sentinel plots were planted in 21 counties (Adams, Amite, Claiborne, DeSoto, Hancock, Harrison, Hinds, Issaquena, Jackson, Monroe, Newton, Noxubee, Pearl River, Pike, Tippah, Tishomingo, Walthall, Warren, Washington, Wayne, and Wilkinson). In addition, three of the locations (Amite, Wayne, and Wilkinson) were surrounded by electrified fencing to reduce the chance of deer predation (see attached photo of the Wayne County plot included as Figure 1). In addition to scouting sentinel plots on an almost weekly basis from April through September (or when they reached R8 or physiological maturity), a total of 475 unique commercial soybean fields throughout the state as well as 367 kudzu patches were monitored during 2012 (see map included as Figure 2). Commercial soybean fields were monitored for the presence of numerous, economically important diseases and nematodes. If and when issues were observed, the information was reported to the state s producers so that remedial measures could be selected and applied. Beginning in 2011/2012, MSU faculty and staff emeritus began to use sentinel plots as well as commercial soybean fields to monitor for all economically important soybean diseases, particularly those that could be managed with a timely fungicide application. In addition to monitoring for the presence of important diseases (e.g, Cercospora blight, frogeye leaf spot, soybean rust, target spot), we also contributed leaf samples to Dr. Carl Bradley at the University of Illinois to monitor for the presence of strobilurin-resistant fungi. The strobilurin class of fungicides (or QoI fungicides) have been widely used in soybean production systems throughout MS and have provided farmers with a broad-spectrum fungicide that has additional benefits when it comes to enhancing yield in continuous soybean systems. Objective 2. If the ability arises, determine the most effective fungicide management schemes by conducting efficacy trials specifically for soybean rust (SBR) timing. In addition, if strobilurin-resistant aerial web blight, Cercospora blight, or frogeye leaf spot are identified, fungicide trial plots could provide valuable information to the soybean industry (if identified early enough). Large-plot trial locations were conducted and data collection was limited. Due to time constraints, we were not able to collect samples or weigh grain from treated plots. However, one location in the Delta was evaluated to determine the benefits of Priaxor on Cercospora blight.

3 The application was made by air at approximately R5.1 and yield did not differ between the treated and non-treated plots. A second plot location near Water Valley, MS was sprayed with Priaxor as a rescue treatment for aerial web blight since the first fungicide application was deemed to be insufficient to manage the disease. Fungal isolates were collected from both locations and will be analyzed shortly in Starkville, MS for the presence of fungicide resistance. Soybean rust was detected in all 82 counties in MS (76 on soybean, 6 on kudzu) in Although the disease was detected earlier than normal (July on soybean) and we were able to find the disease in all 82 counties, yield loss as a result of soybean rust was still low except in a few fields. Conversely, AL reported some yield losses greater than 25% as a result of early infection and farmers not applying a fungicide in a timely manner. During the 2012 soybean season, the following economically important diseases were detected. Foliar fungal diseases: -aerial web blight -brown spot -Cercospora blight -downy mildew -frogeye leaf spot -soybean rust -target spot Viruses: -soybean mosaic virus -vein necrosis virus Soilborne diseases: -charcoal root rot -red crown rot (Oktibbeha County) -southern blight -stem canker -sudden death syndrome Nematodes: -reniform nematode -root-knot nematode -soybean cyst nematode Objective 3. Continue to monitor the environmental conditions at 3 locations (Eden, Hurley, Pond) where weather stations are present to determine if a specific correlation exists between environmental variables and infection of the local plant material (either kudzu or soybean) by the SBR fungus. Throughout the 2012 season we continued to collect environmental information from the three weather stations in southern MS. We are in the process of determining how we might add the weather stations to the list of stations that are already used to upload information to the internet without someone physically going and downloading the information from the weather station. Objective 4. Continue to make weekly radio updates during the soybean growing season for the Mississippi Radio Network (via Mr. Lynn Sheldon and/or Mr. John Winfield) on important topics occurring in soybean pathology or other pathology-related issues (e.g. foliar diseases, nematodes, fungicide application suggestions, presence of particular diseases and their proximity to the major production areas). Throughout the 2012 season radio updates regarding pertinent disease information were made on the MS Ag Network.

4 IMPACTS AND BENEFITS TO MISSISSIPPI SOYBEAN PRODUCERS Ideally, monitoring for yield limiting diseases throughout MS impacts all 2+ million acres of soybeans planted annually. As a team during 2012 (Billy Moore, Tom Allen, Andy Milling, Mike Steede), we observed more soybean acres in MS than any other single entity. Our weekly visits to soybean farms, sentinel plots, and kudzu patches throughout the MS soybean production area provided constant benefit to soybean farmers by showing we are aware of their needs as well as monitoring their crop acres should an issue arise. In locations where soybean rust was observed early, such as in George County on the farm of Mr. Artesia Farrell, we were able to suggest a fungicide to prevent yield loss as a result of soybean rust. In addition, while we were scouting Mr. Farrell s acres, we were also able to address additional issues on his farm that included root-knot nematode, southern blight, and a moderate soybean rust infection at early reproductive growth stages. END PRODUCTS Throughout the season, updates were provided to the farming community through the Mississippi Crop Situation Blog as well as radio interview/updates on pertinent disease management issues on the Mississippi Radio Network. Funds provided by the MSPB allowed us to spend considerable time on monitoring what diseases were present throughout the state, where they were located, and provide this information to farmers through several different outlets. During 2012, information regarding disease observations and their potential management options were distributed to the farming community via the following. Mississippi Crop Situation Blog updates (12). April 13, 2012 Allen, T.W Mississippi soybean sentinel plot program. Mississippi Crop Situation Blog. May 3, 2012 Allen, T.W Soybean seedling disease identification: Pythium damping-off and root rot. Mississippi Crop Situation Blog. May 18, 2012 Allen, T.W Southern blight of soybean observed in a few isolated fields. Mississippi Crop Situation Blog. June 15, 2012 Allen, T.W Preventive soybean fungicide applications: products, rate selection, timing. Mississippi Crop Situation Blog. July 16, 2012 Allen, T.W., and Irby, T Soybean rust detected in a sentinel plot and commercial soybean

5 fields in George County. Mississippi Crop Situation Blog. July 21, 2012 Allen, T.W General soybean disease update: July 21, Mississippi Crop Situation Blog. July 30, 2012 Allen, T.W., and Irby, T Soybean rust update: July 30, Mississippi Crop Situation Blog. August 3, 2012 Irby, T., and Allen, T.W Soybean update and additional management considerations. Mississippi Crop Situation Blog. August 21, 2012 Allen, T.W Soybean foliar disease update: August 21, Mississippi Crop Situation Blog. August 31, 2012 Allen, T.W., and Irby, T Impact of Hurricane Isaac on soybean rust and potential management decisions. Mississippi Crop Situation Blog. September 3, 2012 Allen, T.W Soilborne diseases and disorders of soybean: is it Sudden death syndrome (SDS) or is something else responsible. Mississippi Crop Situation Blog. October 5, 2012 Allen, T.W. Strobilurin-resistant frogeye leaf spot confirmed in Mississippi. Mississippi Crop Situation Blog. Mississippi Radio Network updates (15). Report regarding the status and construction of a rainout shelter to conduct seed quality research in Stoneville, MS. Mississippi Radio Network, April 23, Soybean disease monitoring and soybean rust update. Mississippi Radio Network, May 1, Rainout shelter project sponsored by MSPB. Mississippi Radio Network, May 8, Soybean rust update and general soybean disease outlook. Mississippi Radio Network, May 15, Southern blight showing up in soybean, general disease update, soybean rust report. Mississippi Radio Network, May 23, 2012.

6 Fungicide application at the R3/R4 timing as well as soybean rust update. Mississippi Radio Network, June 7, Diseases of minor important in soybean and a regional soybean rust update. Mississippi Radio Network, June 13, Fungicide use in dryland, non-irrigated soybean situations. Mississippi Radio Network, June 27, General soybean disease update and Downy mildew of soybean: no management practice necessary. Mississippi Radio Network, July 10, General soybean disease update and soybean rust fungicide suggestions. Mississippi Radio Network, July 17, Frogeye leaf spot update and fungicide suggestions and Pike and Jefferson County soybean rust finds. Mississippi Radio Network, July 27, Soybean disease update with specifics regarding soybean rust. Mississippi Radio Network, August 8, Soybean disease wrap up. Mississippi Radio Network, September 15, Presentations (16). Current and future plant disease issues facing MS row crop producers. MCIA Annual Meeting, Biloxi, MS, February 10, MS Plant disease situation Mississippi Agricultural Consultants Association Meeting, Starkville, MS, February 14, Foliar fungicide and insecticide impact on yield and net returns in Mississippi Soybean NCERA-212 meeting, March 6, 2012, Pensacola, FL. New disease situations in southern soybean production systems NCERA-212 meeting, March 6, 2012, Pensacola, FL. Foliar fungicides to prevent yield loss attributed to aerial web blight in Mississippi: 2010 and Southern Soybean Disease Workers, Pensacola, FL, March 8, Scouting for plant disease in corn, cotton, and soybean. Presentation made for the MS Scout School, Stoneville, MS, May 29, Scouting for plant disease in corn, cotton, and soybean. Presentation made for the MS Scout School, Starkville, MS, May 31, 2012.

7 Scouting for plant disease in corn, cotton, and soybean. Presentation made for the MS Scout School, Verona, MS, June 5, Scouting for plant disease in corn, cotton, and soybean. Presentation made for the MS Scout School, Clarksdale, MS, June 7, Proper fungicide use and timing for soybean farmers. Presentation made to local farmers and distributor representatives, Brooksville, MS, June 14, Row crop disease management corn, cotton, and soybean. Presentation made at the Agronomic Crops Field Day, Starkville, MS, July 19, Plant pathology general disease situation, fungicide use, and research trial update. Presentation made at the DREC Field Day, Stoneville, MS, July 19, Soybean disease update and row crop disease management. Presentation made at the North Mississippi Row Crops Field Day, Verona, MS, August 9, Early fungicide strategies in corn and soybean. Presentation made at the Delta Crop Summit, Stoneville, MS, November 13, Disease management in cotton and soybean. Presentation made at the Row Crop Short Course, Starkville, MS, November 13, Row crop disease management. Presentation made to Calhoun County farmers and agriculture community members, Pittsboro, MS, December 11, Proceedings. Allen, T.W., Coker, C.M., Damicone, J.P., Hollier, C.A., Isakeit, T., Joost, R., Marois, J.J., Monfort, W.S., Mueller, J.D., Wright, D.L., and Sikora, E.J A sentinel plot network across the southern United States: IPM to protect the U.S. Soybean Industry. 7 th International Integrated Pest Management Symposium, Memphis, TN, March 27-29, Refereed publications associated with MS disease monitoring efforts. Mundt, C.C., Wallace, L.D., Allen, T.W., Hollier, C.A., Kemerait, R.C., and Sikora, E.J Initial epidemic area is strongly associated with the yearly extent of soybean rust spread in North America. Biological Invasions DOI /s z. Future plans for output (3 refereed publications). 1) Presently, we (a national effort) are drafting a Feature Article to be published in Plant Disease regarding the soybean rust/disease monitoring that has been ongoing in the U.S. since Several drafts have been sent for review by the 3 main authors [Kiersten Wise (Purdue University), Ed Sikora (Auburn University), and Tom Allen

8 (MSU)]. The article would not have been possible without continued funding from the MSPB. 2) The 2012 season was the last year for the soybean rust hotline. A manuscript is being drafted regarding the connectedness of the telephone calls made to the hotline and how soybean rust information was disseminated. Much of this information can be used in presentations as well as included on the MSPB website once it has been completed. However, it may be several months (likely 10-12) before this will be completed. 3) A regional effort (AL, LA, MS) will be turned into an update regarding soybean rust in the U.S. since Much of the information to be contained in this particular manuscript would not have been possible without funding from the state check-off board. Graphics/Tables Figure 1. Photo of the sentinel plot in Wayne County, MS shortly after planting. Electrified fencing can be important at some sentinel plot locations to reduce the likelihood of deer browsing.

9 Figure 2. Map of scouted locations throughout MS that were relied on to gather important disease monitoring information. Red counties indicate a location where soybean rust was detected. During 2012, soybean rust was detected in all 72 counties (77 soybean, 5 kudzu).