Watch out for these early-season issues
A combination of a warm winter, early planting window and now a dry, hot start to summer has caused some crop diseases and issues to blow up in parts of the Corn Belt, specialists say.
The good news is the hot, dry weather has kept some more common diseases at bay more than usual, says University of Illinois crop scientist Carl Bradley. Things like leaf blight and spot, in both corn and soybeans, have affected fewer plants this year on account of the weather.
"Weather is the major factor influencing plant diseases, and the relatively dry weather of late has contributed to the lack of diseases being seen," Bradley says.
Anthracnose leaf blight and Holcus leaf spot, both in corn, are showing up in some fields, but both are less problematic than normal because of the heat and its corresponding stimulus to crop growth.
"When corn plants begin to develop rapidly as the temperatures warm up, they tend to 'outgrow' this disease, with new leaves generally not being affected," Bradley says of Anthracnose leaf blight.
But, while the weather's stemmed the potential growth of diseases like these, it's also helped others thrive. Take Goss's Wilt in corn; in a normal year, early June's typically way too early for this disease to become a problem. But, agronomists in Nebraska say this year's been different so far.
"The disease can develop at any time during the growing season, but it has not typically developed this early in eastern Nebraska. Its impacts on yield are worsened the earlier it develops during the plants’ growth stages and the more leaf area that is affected by lesions. Development of the disease now on susceptible hybrids could have devastating impacts on yield if the disease continues to worsen in those fields," says Tamra Jackson-Ziems, a plant pathologist with the University of Nebraska Extension. "The disease does not appear to be widespread at this time, but scouting is recommended, particularly in high risk fields, to determine if disease has developed and to what extent."
Then there are conditions that, though not technically diseases, have taken their toll on the corn crop. Rootless corn syndrome has been an issue from the Plains to the eastern Corn Belt. Caused most often by dry conditions at and following planting, the syndrome causes both stunted and altogether failed root development, and it's been showing up a lot more than normal this year so far.
"Shortly after emergence, the nodal (or crown) root system begins to develop. It is these nodal roots that become the permanent root system. More roots develop from successive nodes as the plant develops," says University of Nebraska agronomist Tom Hoegemeyer. "Lots of conditions have been observed to cause this rootless appearance, most of them related to weather or planting. Planting too shallow (less than 1.5 inches) can be a problem, especially if heavy rain compacts or erodes the soil."