Anne Dorrance, Pierce Paul
Stand and seedling problems in soybeans
Believe it or not parts of the state have significant amounts of corn and soybean planted. With our “shortened” spring it is going to be very important to assess fields and your seed treatments as soon as possible. Target those fields that receive 3 or more inches of rain and dig in the rows to find the seed. If the seedlings have beautiful white roots gently replant them. However, if the seedlings have areas on the root or hypocotyl that are soft brown, tan to dark brown; they are not going to make it. Corn and soybean are vulnerable to a number of seedling pathogens.
Pythium spp. We have identified more than 25 different species of Pythium that are highly pathogenic on both corn and soybean. Interestingly or puzzling is the fact that each of the seed treatments for Pythium are not effective towards all of these species (metalaxyl or strobilurin). If you do have stand failure it is important to reexamine the seed treatment and be sure to have a good mix and higher rates of products.
We have two Phytophthora’s in the state, P. sojae for soybean and P. sansomeana which infect both corn and soybean.
Finally, Rhizoctonia and Fusarium spp., particularly Fusarium graminearum can also infect young seedlings of both corn and soybean. We have observed F. graminearum most often in fields with a lot of corn residue.
As part of a regional study, we are collecting samples of seedlings with these symptoms of seedling blight and damping-off. Place seedlings in a plastic bag – no extra water and no paper towel. Put it in a box that won’t get crushed during mailing and ship to:
Soybean Pathology Lab, The Ohio State University/OARDC, 1680 Madison Ave., Wooster, OH 44691
Source : osu.edu