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Green Weeds Complicate Early Corn, Soybean Harvest

25 September 2012

US - Fields with actively growing weedsfrom this summer's drought and recent rains could create problems for farmersduring harvest, a Purdue Extension weed scientist says.

The rain, along with early spring-planted crops and thedrought have led to fields that contain green weeds along with mature corn andsoybean crops. "It's a statewide issue," Bill Johnson said."Wherever we've gotten rain in the past few weeks we're seeing weeds popup."

Late-summer droughts or killing frost usually dry out theground so new, green weed growth isn't a problem for farmers. But this yearcrops are maturing earlier than normal and a killing frost is still weeks away.

Mr Johnson recommended that farmers use herbicides to get ridof weeds and dry out the ground to prevent future weed growth so they can havea timely harvest. But, he said, not many herbicides can be used soon beforeharvest.

"Herbicide application isn't mandatory, but it's goodpractice. If the weed growth is bad enough, it could create more wear and tearon machinery and hurt grain quality when harvesting crops," Mr Johnson said.

Harvest equipment is designed to gather mature crops, notgreen growth. Green weeds going through combines and other harvesting equipmentcan cause the machinery to break down and delay harvest.

Many fields, especially those with soybeans, are maturingunevenly in face of the extensive drought and will make harvest-aid herbicideapplications and harvest in general a challenge this fall.

Green weeds intermingled with corn and soybeans also cancause other problems after harvest.

"Weeds can increase moisture in yields and decreasegrain quality," Mr Johnson said.

In a year where crop yields and grain quality are already expected to be low, producers don't need extra problems like weeds messing withtheir harvests.

According to Mr Johnson, weeds that are actively popping upin fields across Indiana include morning glories, velvetleaf, foxtail, winterannuals and cover crops that are already starting to regerminate.

When applying herbicides to eradicate weeds, Mr Johnson reminds producers that most harvest aid products are contact herbicides andselection of spray volumes and nozzles is crucial to adequate coverage.

"Choose nozzles that allow for smaller droplets topenetrate the canopy and cover vegetation but are also large enough to avoiddrift issues," he said.

Most labels recommend at least 10 gallons per acre forground applications and a minimum of 5 gallons per acre for aerialapplications.

Mr Johnson and Travis Legleiter, a weed science programspecialist, advise producers to check the herbicide label for properapplication techniques prior to use. They've prepared a table outliningproducts that can be used as harvest aids in corn and soybeans, which can befound online at

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