For those still intending to apply a foliar fungicide to soybean, if you are using a triazole or triazole-containing product please be careful about the additives you include. Some folks are reporting foliar leaf burn very similar in appearance to Sudden Death Syndrome (yellow to brown areas between leaf veins). Injury seems to be the result of adding additional products (crop oil, glyphosate, micronutrients, some insecticides) not required on the fungicide label, to a triazole product. The hot weather we have been experiencing may be making the situation worse.
SDS generally shows up in spots in the field, and affected plants have brown vascular tissue with some rot on roots. New leaves emerging from the growing point will often show disease symptomology. Spray damage is typically visible only on affected leaves, lower stems are healthy and new trifoliates produced after the sprayer has left the field will be green and look normal. Dr. Newman has not had any measurable yield loss with leaf burn in some of his plot work, but the injury symptoms may be very worrisome. So, check your product labels and try not to go overboard with the additives.
I’m one of those that applied surfactant with a comb fungicide. Days later I thought the field had significant stem canker. My reasoning for the surfactant was the 100 degree temps and increased coverage.
Melvin typically puts a spreader/sticker in with his fungicide to help with leaf wetting, even though some products have no recommendation to add one in soybean. He noticed more burn this year with some of the combination work at Milan. I think more folks are using combos or adding triazole products into the mix this year and the hot temperatures may be adding to the symtomology.