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Posted 29 June 2015. PMN Crop News.

Once Forgotten, Pythium Back on the Radar

Source: United Soybean Board Press Release.

Chesterfield, Missouri (June 3, 2015)--There are many different pathogens and diseases that soybean farmers are watching for in their fields. One such pathogen, Pythium, has recently been the subject of research by Jim Kurle, University of Minnesota Department of Plant Pathology associate professor.


“The last time anyone really looked closely at Pythium was probably close to 30 years ago,” says Kurle (pictured above). “It’s an important pathogen because it is a real problem in terms of early-season stand establishment, especially when there is excessive soil moisture or soil temperatures are low.”

There are now 30 identified Pythium species in Minnesota soils alone, which is considerably more than researchers knew existed previously. This means that farmers cannot focus on one single species to manage or control. Some of these species infect both soybeans and corn.

“There are a number of species, about four, that are pathogenic on both corn and soybeans,” Kurle said. “So the concern here is that they will be very difficult to manage using crop rotation. It also means they actually increase on either crop.”

Pythium pathogens are active at low temperatures and in wetter soils. A component of this study looking at a range of temperatures found a number of Pythium species are actually pathogenic and more active in warmer temperatures. Kurle pointed out that this may explain some of the root rot stand establishment problems farmers and researchers have seen under more ideal drying conditions.

The Pythium species used to be called a fungus at one time, but they actually behave differently.

“While this might seem to be the kind of information only scientists are interested in,” Kurle says, “it is very relevant because species like Pythium and Phytophthora are oomycetes. This means they are susceptible to a different group of fungicides than the typical treatments for fungi like Fusarium and Rhizoctonia, and so there needs to be different components used in seed treatment if you are dealing with Pythium.”

Kurle’s study shows that a number of seed treatments are effective on Pythium, at least very early. For farmers, that can be helpful in stand establishment.

Kurle’s research on Pythium is being funded in part by the Minnesota Soybean Research and Promotion Council. Look for future information on his research at

Courtesy Minnesota Soybean Research & Promotion Council