Agronomists with the University of Illinois and Purdue University are taking note of weather-related seedling issues, urging producers to begin scouting their fields.
Purdue University plant pathologist Kiersten Wise says many eastern Corn Belt field planted in mid-April are showing signs of seedling blights. She says blights can be caused from cold temps, nutrient deficiencies, herbicide or anhydrous ammonia injury, wireworms or "wet feet," but also could be caused by seedling blights from fungi or fungal-like organisms.
Wise says growers can assess the level of seedling blight damage in their field and if enough of the stand is lost, fields might need to be replanted. "Roots of infected plants may be brown and discolored and can be soft or mushy," Wise said. "Infected plants may also have brown discoloration on the mesocotyl."
Before making replanting decisions, however, Wise suggests farmers read this publication.
University of Illinois agronomist Emerson Nafziger says the return to warm temps has resulted in rapid growth of the corn crop, but the dry pattern is also causing some concern. And while the state’s corn crop is nearly all planted and much of the crop is growing well, there are reports of "floppy" corn plants in western and northwestern Illinois and into southeastern Iowa.
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"It’s an easy problem to spot," said Nafziger. "Plants develop using water provided by the seminal (seed) root system up to the 3- to 5-leaf stage, after which the nodal roots -- those that develop from the base of the stalk -- take over and become the main root system for the rest of the season. If the nodal root system fails to develop, the plant become wobbly and may fall over; hence the name "floppy" corn. This problem has also been called "rootless" corn due to the absence of nodal roots."
Plants growing in dry soil often show some degree of purpling as well. Having plants turn purple may be preferable to having them turn pale green. "This is because purpling results from sugar accumulation in the plant, and sugars cannot accumulate without photosynthesis," said Nafziger.
"One question is whether plants perched on top of the soil will recover to become fully productive even if rain wets the soil enough to allow nodal roots to penetrate it and grow. Such roots tend to grow downward at a steep angle, which might give the plant a small advantage. But there may be fewer roots, and rapid water uptake might be a challenge," says Nafziger. "The risk of lodging will also increase due to less anchoring by the root system."