Farm Progress

Assess corn rootworm control nowAssess corn rootworm control now

Checking performance of rootworm control this summer can help you plan for 2018 product selection.

July 18, 2017

4 Min Read
TAKING A TALLY: The third week of July is ideal time to evaluate cornfields for root damage and for emerging corn rootworm adult beetles. Peak beetle emergence generally coincides with corn pollination.

While harvest may be on the mind of some farmers, thoughts of hybrid selection for 2018 planting can seem premature. But according to Sean Evans, technology development manager at Monsanto, taking time to evaluate fields now will help farmers place the right product on the right acre to get the best return in 2018.

Planting delays caused by wet spring weather may provide more opportunities for corn rootworm populations in 2018. Adult corn rootworm beetles are attracted to green silks and pollen, so fields at risk for beetle invasions now include fields planted to later-maturing hybrids; delayed plant development because of uneven emergence; late-season weed populations; and in some cases, even adjacency to weedy soybean fields can attract a large number of egg-laying adult beetles.

As corn transitions from the vegetative to reproductive stage during the mid-July through August time frame, farmers’ field evaluations should center on plant development and overall plant health. This is the time to evaluate the plant, looking for signs of heat and drought stress, and any nutrient deficiencies. Pests and weeds can appear in full force, so be ready to respond if pressure is high.

Take time to evaluate corn roots
One pest to pay particular attention to is corn rootworm. According to USDA, perhaps the largest contributor to yield damage is the corn rootworm. Even moderate damage to corn roots by rootworm (also known as the billion-dollar bug) has been shown to cut yield by 15%.

While moderate levels of infestation can cause up to 15% yield loss, “yield losses of 50% or more are not uncommon when infestations are high,” says Evans. “Farmers need a comprehensive plan to control the billion-dollar bug.”

Getting in the field during rootworm hatch in late June and conducting a root dig is ideal, as early monitoring provides a good measure of which fields need to be watched closely for corn rootworm-caused problems. If a farmer didn’t get in the field during the early vegetative stage, the third week of July is the ideal time to evaluate fields for root damage and emerging corn rootworm adult beetles.

Peak beetle emergence at pollination
“The peak beetle emergence generally coincides with pollination and is a key period for field evaluations of product performance,” Evans notes.

Insect pest management is key to managing corn rootworm. “There is no silver bullet for controlling this pest,” he says. “Rootworm is an insect that’s best controlled with multiple tactics, including crop rotation, trait technology, soil-applied insecticide and, if absolutely necessary, foliar insecticide sprays. Deciding how to control corn rootworm is a big decision. If you are wrong, it can cost a lot.”

If your July field evaluations indicate a corn rootworm beetle population that is meeting thresholds, a proactive approach to next year’s crop may be a better management tactic than spraying now to suppress adult beetles. “Knowledge that can only be gained with field evaluations is the best way to go about selecting the products to place on your fields,” Evans says. “Only by spending time in the field to determine the assets and challenges that exist can a farmer make an informed product selection.”

Best defense is good offense
When considering a corn hybrid to plant in a field, the first consideration is yield goal followed by maturity and the growing degree units required for physiological maturity. Planting a range of product maturities can help reduce damage from diseases and environmental stress at different growth stages, while also spreading out harvesttime and workload.

“A majority of the acres in a farming operation generally should be planted to mid- and full-season corn hybrids due to the higher yield potential,” says Evans.

Farmers should consider soil type, tillage practices, the fertility program and what disease package is needed, followed by insect protection through traits. “If the field is at risk for corn rootworm, a full-season insect control option may be needed and the best product might be a SmartStax RIB Complete corn blend,” he says.

SmartStax RIB Complete provides full-season corn rootworm control for heavy-pressure situations like fields with a history of corn following corn. Also, SmartStax products provide insect control of the most above- and belowground insects, and it has two modes of action for maximum control over corn rootworm. The mix of 95% traited and 5% refuge seed allows a farmer to fill the planter and go.

To learn more about SmartStax and VT Double PRO RIB Complete products, contact a local seed dealer or find a local Genuity dealer at ​​​​​​​​​​​​​​​​​​

Source: Monsanto


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