KNOXVILLE — Dry weather and heat are taking its toll on row crop across Marion County.
Rebecca Vittetoe, a field agronomist for the Iowa State Extension and Outreach in Marion County, said the heat and dry conditions are stressing the crops.
“Right now corn is pollinating or has pollinated, and now is not when we want to be experiencing a lot of stress,” she said. “This could affect how many kernels get pollinated, and also how many kernels get filled.”
Vittetoe said she is not too worried about soy beans as of yet. Typically corn begins to produce in July and soybeans in August.
The fields Vittetoe has walked through shows that pollination has occurred. She said she is beginning to see some tipping back. Tipping back is when pollinated kernels begin to abort the plant because the plant cannot fill them.
She said she has also seen some cornfields “firing.” This is when the leaves in the lower canopy of the corn begin to turn yellow and brown. The “firing” has began to move up the plant in some areas. Fields with sandy or compacted soil is where she has seen the most “firing.”
What Vittetoe has noticed with most cornfields in the area, is corn rolling the leaves.
“This is the [corn’s] defense of trying to conserve as much water as possible,” Vittetoe said.
It’s too early to know how much of an impact the heat and lack of moisture will have on the corn. Vittetoe said crops react the same way as humans. Humans do not do as well in extreme hit and little water.
Another issue that comes with the hot and dry weather is the impact herbicides have on weeds in row crops.
“From a weed standpoint, the hot weather makes it harder to kill weeds,” Vittetoe said. “When farmers were making their post applications in June and the first part of July, it was really hot.”
The hot and dry weather is also causing spider mite populations to build-up, Vittetoe said. Spider mites feed on the leaves of both corn and soybean plants.
Farmers should be keeping an eye out for spider mites. They are usually found on the underside of leaves, she continued. Spider mites are tiny and hard to see.
To check for spider mites, Vittetoe said hitting the underside of a leaf with a white piece of paper can help in detecting whether or not plants have them.
“If the hot and dry weather continues, we will likely see an early harvest,” Vittetoe said. “The next two weeks will really tell us on the corn side, especially with corn silage. The concern with silage is nitrate toxicity.”
Corn silage is when farmers use the entire plant to make feed and not just the grain, she added.
The bottom line is, if Southeast Iowa does not see rain soon, “It’s not looking good for the crops, especially the corn,” Vittetoe said.