What can growers do, right now, to help reduce the devastating effects pathogens, such as aphanomyces and fusarium, have on pulse crops?
Michael Wunsch, plant pathologist with North Dakota State University, joins Kara Oosterhuis for this Pulse School episode to talk about what is and isn’t in farmers’ control.
Wunsch’s approach to disease management includes practical and applied research and aims to provide practices that farmers can implement “tomorrow.”
For fusarium and aphanomyces root rot, Wunsch has researched the return on investment for a fungicide seed treatment, and the impact soil temperature has on the effectiveness of these treatments. He’s also measured the impact of planting date.
“We know fusarium and aphanomyces are warm-temperature pathogens, and we had seen, anecdotally, that planting early seemed to reduce the root rot severity of these diseases,” says Wunsch.
Wunsch and his research team also looked at the use of crop rotation, which seems like a no brainer (and is the top recommendation for management, still), but fusarium and aphanomyces are notoriously long-lived in soils, so there may be more strategy to apply than just rotation.
Catch the full conversation for more details on the research methods, including planting dates and experimental design as well as key findings:
Widening crop rotations was also a part of Wunsch’s previous work at sites with and without previous histories of fusarium and aphanomyces in peas. He tested two, three, four, and six year rotations, comparing the data between the rotations.
“Soil temperature is the key here when it comes to planting date and how to optimize field pea agronomy performance,” says Wunsch.
Wunsch explains that root rot severity was less when the soil temperature was below 10 degrees C in the week after planting, at seeding depth, but emergence was very poor when temperatures were below 7.5 degrees C.
“The sweet spot for yield, where you maximize your yield, i.e. you reduce your root rot, but didn’t have terrible emergence problems, was between 7.5 and 10 degrees C at that two inch depth below the soil surface,” says Wunsch.
One of the things to remember is that when planting into cool soils, and there’s a history of other root rot pathogens, like rhizoctonia or pythium, a fungicide seed treatment becomes very important. As Wunsch warns though, a fungicide seed treatment and soil temperature aren’t enough for this fight — good crop rotation practices are also important.
“When we grew peas once every six years, and used a fungicide treatment and planted early, we were getting 48 to 49 bushel peas, in a field with horrible root rot pressure,” says Wunsch. “When we planted every four years, we got 39 to 40 bushel peas with the same practices.”