New soybean disease in Midsouth named taproot decline

In Delta Farm Press

A report from the 2016 Tri-State Soybean meeting

The Mid-South’s soybean “mystery malady” now has a name — taproot decline. Unfortunately, as those at the 2016 Tri-State Soybean Meeting heard, there remain many questions about treatment.

“When I started in 2007, I received numerous calls from consultants about a root-associated soybean disease that appeared different than the other root diseases in the Mid-South,” said Tom Allen, Mississippi State University plant pathologist. “Looking back, and based on some of the more prominent symptoms associated with this root disease, I think the disease was likely misdiagnosed as one of several other root-associated soybean diseases.

“When considering the specific time of year that most diseases occur, the vast majority of foliar diseases in Mississippi — and this also holds true for Arkansas and Louisiana — occur during reproductive growth stages.”

That doesn’t mean some of the root-associated diseases aren’t the result of infection that occurs earlier in the season. However, “the symptoms associated with those diseases are not generally observed until later in the growing season. The diseases that result from early infection but are not observed until advanced reproductive growth stages include Phytopthera root rot, charcoal rot, red crown rot, stem canker, SDS, and some nematode-related issues. In the field, the symptoms associated with these specific diseases are not generally observed until R5-plus.”

This new root-associated disease is interesting, said Allen, “because, quite frankly, if you know what you’re looking for the disease can be observed at both vegetative and reproductive growth stages. To properly observe and diagnose this new root disease you’ll have to spend a lot of time on your hands and knees looking at potentially infected plants.”

There is now a name “for what we have previously referred to as ‘the mystery disease.’ We are now referring to this particular disease as taproot decline. My colleagues from other states waited to name the disease until we were all on the same page to try and prevent confusion between states.”

For the rest of the story, read Delta Farm Press.

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