Recent heavy rains have caused problems for farmers in south central Illinois; we’re seeing phytopthora root rot affecting soybean fields. Phytophthora is a soil-borne water mold common in fields that are saturated and not well drained. Phytophthora can affect the plant at two different stages; one specifically targeting the stem. This happens before the root system is developed and during the VE/emergence stage. We call this the seedling blight phase, which can cause damping off. The second affects the roots of larger, more developed plants. The fungus infects the roots and grows into and along the root cells of the plants, which is what we are seeing right now.
Phytophthora root rot can be fairly easy to detect when dealing with the root rot stage. The roots will be a discolored brown and root nodulation will be minimal, causing a chlorotic nitrogen deficient plant. The disease will move up the stem from the soil line and dark to reddish brown lesions will continue up the stem. The dead tissue quickly becomes soft and water soaked. The plant will soon look wilted and chlorotic (yellowing) leading to death of the plant. Sometimes a few plants will be affected and other times large areas of the field will be affected. This disease generally affects individual plants within a row (one out of seven to 10 plants may be affected.) Infected plants will eventually wilt and die, with the leaves still intact but delivering devastating yield loss.
If your fields are affected by phytohphora root rot this year, there’s really nothing you can do about it this growing season. However, growers can plant varieties with phytophora resistance along with seed treatments to protect seedlings from the disease in future years. Stine has an outstanding lineup of Rps 1a/1c/3a phytophthora root rot-resistant varieties in its lineup for 2019. Additionally, our Stine XP seed treatments contain fungicides to protect your seed investment from unwanted soil-borne pathogens. Stine XP Complete, Stine XP-F&I and Stine XP-F all boast resistance to phytophthora spp.
To learn more about phytophthora root rot detection and prevention, contact your local Stine sales agronomist.