We will be conducting a Soybean Scout School on Thursday, July 22 beginning at 10:00 a.m. at Summitville Grain and Feed Co. located at 219 Clark Rd, Manchester, TN 37355. We have lunch provided by Summitville Grain and Feed Co. If you are planning to attend, please RSVP for lunch by either e-mailing me at firstname.lastname@example.org or calling our UT-TSU Extension Office at 931-723-5141 by Wednesday, July 20. Our University of Tennessee Crop Production Specialist will be our instructors. Below is a list of our instructors and the topic they will be teaching about.
Dr. Heather Kelly – Diseases
Dr. Scott Stewart and Sandy Steckel – Insects
Dr. Larry Steckel – Weed Control
Dr. Angela McClure – Growth and Development
Dr. Nutifafa Adotey – Soil Fertility
Ryan Blair – Variety Selection
We will begin the program and have lunch at Summitville Grain and Feed Co. and end by visiting a nearby soybean field following lunch. If you have any questions, call our UT-TSU Extension Office at 931-723-5141.
Foliar Fungicides for Soybean Diseases
Some local soybean producers are now spraying their soybeans with a foliar fungicide. The best time to spray for late season diseases is at the R3 stage of growth. Under heavy disease conditions, and when soybean prices are really good, a second application might be beneficial at the R5 growth stage. The recent rains have made prospects look good for excellent yields, but that good moisture also creates the conditions for more late-season foliar diseases.
Moisture is the number one factor needed for disease development, but along with moisture, continuous soybeans, susceptible varieties and low soil fertility (especially low potassium and low pH) also increase the chances for yield loss from disease. Producers should consider spraying fields that are subject to these conditions. However, if there is little hope for a good yield (at least 30 + bushels per acre) spraying a fungicide might not be as economical as one that has a high yield potential.
Fungicide coverage of as many leaves and stems as possible is essential for good foliar disease control. If spraying with ground equipment, use at least 15 to 20 gallons of water per acre along with a fine droplet size (about 250 to 300 microns) and high pressure. If spraying with an airplane use at least 5 gallons water per acre and fly 6 to 12 feet above the soybean canopy.
Soybean rust is not a threat in Coffee County at this time. Therefore, all that is needed for control of late season diseases is an EPA approved Strobilurin fungicide such as Headline or Quadris with a surfactant such as NIS or a COC. A premix or tank mix of a Strobilurin plus a Triazole fungicide is also effective as long as there is an adequate amount of Strobilurin in the mix. When making a second application, it is wise to use a tank mix or a premix of Strobilurin plus a Triazole. This would help reduce the chances of a built-up of resistant fungi to the Strobilurin fungicides and help reduce the risk of soybean rust.
Using just a Triazole for late season diseases such as Brown Spot, Frogeye Leaf Spot and Anthracnose would not be the best choice for maximum control. Basically, the Triazoles are best used for soybean rust control. Triazoles are necessary when there is a high risk for soybean rust. The risk of rust is low at this time. We are continuing to monitor the rust situation by scouting sentinel plots and checking spore traps.
For more information on soybean diseases, disease resistant varieties and fungicides check the utcrops.com web site under soybean diseases.