Trees sprout up as pests in no-till fields
No-till farming has numerous benefits, but one issue that comes with the practice is trees sprouting up in fields next to corn and soybeans.
“They like undisturbed soil,” says Lowell Sandell, weed science Extension educator with the University of Nebraska-Lincoln. “No-till is ideal for establishment of the trees.”
Eastern red cedar is the most common tree to invade no-till fields, but Siberian elm and honey locust trees are also problems. And since the amount of herbicides needed to kill these trees will kill soybeans and corn plants, several different tools must be utilized to control the trees.
“It depends on how dense or widespread the problem is. Then it may only require spot treatment,” Sandell adds.
At a glance
• One of the downsides of no-till is the emergence of trees as pests.
• Red cedar is the biggest pest, but honey locust, Siberian elm are problems, too.
• Soil disturbance will help, but you lose no-till’s benefits.
Spot treatment includes walking or riding a four-wheeler through the field and applying herbicide to the trees. The ideal time to apply herbicide is when the trees are in full foliage, so they soak up the chemicals better. Spring is also a good time of year for spot treatment — once the plant has greened up and is actively growing to take up the herbicide.
Sandell says that the combine headers used on soybeans also contribute to the problem because they “just kind of chop everything off,” and then while the top of the tree has been sheared off and it appears dead, it could still come back the following year.
“We do no-till for soil conservation and to save trips across the field, but on the flip side it causes these problems,” Sandell says. “You can add some disturbance back to the system, but what you are giving up is soil conservation and erosion prevention.”
Several control options exist for trees up to 2 feet tall, including cutting, pulling, digging, mowing, use of goats and herbicide application. Individual herbicide treatments and cutting can control trees 2 to 10 feet tall; cutting is the most effective method for trees more than 10 feet tall. While 10-foot trees do not usually exist in fields, Sandell suggests removing large seed trees from fence lines to help prevent the spread of seedlings.
The Eastern cedar tree is a non-sprouter, so the tree will not regrow if clipped before the lowest ring of branches. Fire is a tool for rangeland cedar tree infestations, but not for cropland.
“If at all possible, we’d like people to get out and control them before there is a thick stand, and there’s no choice but to use heavy treatment and maybe have to take the field out of production for a year,” Sandell says.
He says a proactive approach is the most effective for keeping trees out of soybean and cornfields.
“The bottom line is, from the ecology side, no-till has created an environment for red cedar to survive and thrive, and herbicides safe for corn and soybeans aren’t effective for trees,” Sandell says. “Being timely about control is the best management tool.”
For more information about herbicide amounts, cost projections and application practices, visit weedscience.unl.edu. Click on “Weed Guide,” then scroll to “Noxious and Troublesome Weeds.”
UNDISTURBED SOIL: Various tree species are sprouting up in no-till fields because they like undisturbed soil. Photo courtesy of Lowell Sandell, UNL
This article published in the September, 2011 edition of NEBRASKA FARMER.
All rights reserved. Copyright Farm Progress Cos. 2011.