The history of diseases in your fields is important to know and should help with future disease management decisions. A Purdue Extension plant pathologist says fields with a history of specific diseases will be more likely to see those appear again.
“A lot of the organisms that cause disease survive in the soil or the residue,” says Kiersten Wise. “So when we plant back in to those fields we are predisposing this year’s crop to the diseases that have been a problem in the past.”
Once soil-borne crop diseases are present in a field, they rarely disappear. When the right weather conditions present themselves, diseases such as sudden death syndrome, root rot, white mold and seedling blight can substantially decrease crop yields. But she says there are some fairly easy preventative management steps that can be taken for front end management of diseases.
“And so if you know of fields that have histories of specific diseases, for example SDS in soybeans, fields that have a history of that disease should always be managed accordingly. We can choose varieties that are more resistant to SDS to plant in to those fields, and we can also try to plant those fields last in the planting order to allows the soils to warm up to make it less favorable for the fungus that causes the disease.”
Weather plays a role in every disease, and Wise says the mild winter could result in more problems with soil-borne diseases in soybeans.
“They’ve been out there with this kind of moisture. They like the moisture and the warmer soils, and so when we plant into this situation we might see a few more issues with soil-borne diseases. Now our foliar diseases, the ones we really worry about in corn, it’s really going to depend more on the environment when corn gets in to tussling more towards July. That environment is going to really influence what disease problems we may see show up.”
Many fungicide purchases have rebates if the orders are placed before the crop is planted. Wise said corn producers should consider a few factors in deciding whether they might need to consider fungicide application.
“If farmers are planting into fields with a lot of residue, if they’re planting susceptible varieties and if their fields are continuous corn, they could possibly benefit from a fungicide later in the season if the environment is favorable for disease development,” she said.
Purdue Extension’s Corn and Soybean Field Guide offers more information and helps producers identify crop diseases throughout the growing season. It’s available for $7 in Purdue Extension’s The Education Store.
Growers who are uncertain about the identification of a disease also can send samples to the Purdue Plant and Pest Diagnostic Laboratory for diagnosis within a few days.