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ST. LOUIS (DTN) -- It's time to rough your cornfields up a little. Conditions are right in many fields for stalk rot this year. A firm push to the plant can alert you in time to minimize harvest losses, said University of Nebraska plant pathologist Tamra Jackson-Ziems.
Plants with the symptoms of stalk rot -- hollow or rotting, weakened stalks -- won't withstand the bullying, she pointed out. "You're basically simulating what wind does, and if you have stalk rot, the plants will not snap back up," she explained. "They'll fall over or stay bent, and you have a potential problem."
The same fungi that encourage stalk rot can also produce ear rots like Diplodia, Gibberella, and Fusarium, Jackson-Ziems noted.
A GOOD YEAR FOR BAD STALKS
Plant pathologists from Indiana, Iowa, Missouri, Minnesota and Nebraska are urging growers to scout now for stalk rots because many Midwestern fields saw the right combination of conditions to produce them this year.
A wet start to the growing season, such as much of the Midwest had, can encourage the early growth and infection of stalk rot pathogens, Jackson-Ziems said. Damaging events later in the season such as hail can exacerbate the problem.
"The pathogens that cause it are pretty much everywhere, and they're very opportunistic; they're sitting around waiting to infect the plant," Jackson-Ziems said. "Leaf wounds are just an open door for the pathogen to infect the plant."
Leaf diseases like Northern Corn Leaf Blight and Gray Leaf Spot were reported in many Midwestern corn fields this summer, and they also play a role in stalk rot.
"The plant is genetically programmed to fill grain at all costs, so it's going to continue to put carbohydrates into those kernels," Jackson-Ziems said. To feed the growing kernels, the plant turns to its "factories" -- the corn's leaves. So when a disease or hail event destroys the leaves, the plant is forced to do a quick and grisly re-routing. "It cannibalizes its own stalk tissue," Jackson-Ziems explained.
Healthy plants with especially high-yielding potential can also be vulnerable to this stalk-sucking phenomenon, noted Iowa State plant pathologist Alison Robertson.
The favorable growing conditions this summer delivered cornfields brimming with kernels, Robertson explained to growers in a university Crop News publication. "The corn plant will do everything to finish off the grain at the expense of using carbohydrates stored in the stalk, consequently leading to increased risk of stalk rots," she concluded.
To evaluate your field for this problem, plant pathologists recommend pushing at least 100 corn plants in a field to test their strength. Alternatively, you can pinch the lower stalk, between nodes, to feel for soft or hollow stems. If more than 10% of the tested stalks prove weak, move that field to the top of your harvesting list.
"Some people say you should even harvest them a little earlier, even if it means you have pay to dry the grain down," Jackson-Ziems added. "Because the alternative is if we have a lot of wind this fall, these plants are going to fall over, which makes harvest a nightmare, and farmers will leave yield on the ground."