<body><div><figure><img src="https://img.particlenews.com/image.php?type=thumbnail_580x000&amp;url=3febu5_0ue9RlcR00" alt="https://img.particlenews.com/image.php?url=3febu5_0ue9RlcR00" width="1200" height="994" ><figcaption>Saturated soils and a full canopy favor the emergence of mushroom-like structures that lead to white mold. Photo courtesy Dylan Mangel/University of Nebraska</figcaption></figure>Increased precipitation this growing season could lead to more crop disease.Like 2010, 2018 and 2020, 2024 crops have seen consistent moisture and some standing water.“In general, I anticipate quite a bit more disease this year,” said Daren Mueller, professor and Extension plant pathologist at Iowa State University. “We’ve had lots of areas in the Midwest with additional or too much rain.”The crop is three or four weeks from seeing stem diseases in soybeans, and stalk rot will likely show up in August, Mueller said.One of the crop diseases of concern to plant pathologists is tar spot. Mueller said lesions of tar spot will show up on the same spot on both sides of a leaf. He said tar spot is sometimes mistaken for insect droppings, which can be wiped away. Tar spot cannot be scraped off.Mueller said tar spot produces spores that can be transported by rain or wind onto new material.“As new lesions appear on corn leaves, the spores can get wind blown and move pretty far,” he said.Mueller said if a field has too much tar spot, it is not worth treating, but plants can withstand low levels.<h2>People are also reading…</h2>If a farmer chooses to treat it, they need to line up the product and consider weather conditions and the stage of growth. Mueller said the longer the wait to treat tar spot, the more competition there is with other farmers to get product to treat the disease.“It’s all about the flexibility and ability to accept risk by the farmer,” he said.Mandy Bish, assistant professor and Extension crop pathologist at the University of Missouri, said tar spot showed up early in Missouri this year. At the beginning of July, tar spot had been confirmed in 19 counties. Bish said corn growers in nearly half of the state’s counties have reported tar spot since Missouri’s first confirmed case in 2018.“Tar spot has been present at low levels and restricted to the lower corn canopy in most of the confirmed cases of 2024,” Bish said.The tar spot fungus overwinters in infested corn residue. The fungus that causes tar spot prefers temperatures in the mid-60s to low 70s.Bish recommends fungicide applications at VT-R3. Fungicide applications earlier than VT and after R4 have not demonstrated a good return on investment, she said.Along with tar spot, Bish said southern rust is equally aggressive and has been seen along the Mississippi River this year. The pathogen comes up from the southern states because it cannot survive Missouri winters.She noted there are some cases of common rust as well, but most corn hybrids are resistant. Bish said the ability to differentiate between these two types of rust is important.Mueller said a disease he has seen this year at low levels is frog eye leaf spot, found in soybeans, which has appeared slightly earlier than is typical. He has also seen the mushroom-like structures that lead to white mold development. He said common rust will likely be seen at a decent level.</div></body>

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Agronomists eye 2024 disease threats

Increased precipitation this growing season could lead to more crop disease. Like 2010, 2018 and 2020, 2024 crops have seen consistent moisture and some standing water. “In general, I anticipate quite a bit more disease this year,” said Daren Mueller, professor and Extension plant pathologist at Iowa State University. “We’ve had lots of areas in the Midwest with additional or too much rain.”

Agronomists eye 2024 disease threats

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