By Michel Elben
CORDOVA, Md., April 17, 2012 — When forage radish was planted as a cover crop last fall in the Delmarva area, farmers expected it to frost-kill within a few cold nights of mid-teen late December weather.
But this year, in many cases, it didn’t. Now new growth is budding from some surviving radishes, and some farmers are faced with chunks that have not yet decomposed.
"This is the first time in five to eight years that (the radishes) haven’t winter killed," saidJim Lewis, Caroline County Extension director and senior agriculture and natural resources agent. "And this winter isn’t even in the top five warmest winters."
Lewis said the radishes are difficult to kill and "the aggravating part is that the more mature (radish) isn’t going to easily decompose."
"The best option is to flail chop them and cut the root off when it's done growing," said Lewis.
Radishes are a good cover crop, said Lewis. He encouraged farmers to make their own decision on the best way to eliminate the crop.
The brassicas can be eradicated when the leaves reach eight to 12 inches in length.
This is when they are large enough to absorb the proper amount of a burn down application. According to Steve Groff, owner of Crop Cover Solutions, one quart per acre of glyphosate and one pint per acre of a 2-4D type herbicide will control tillage radish.
Greg Gannon, who farms in Talbot County, Md., has 600 acres of forage radish planted. He took Groff’s suggestions a week ago and used a combination of disking and herbicide.
Kyle Hutchison, of Hutchison Brothers in Cordova, Md., said he plans to spray the radishes he planted with his barley cover crop and not work them down.
"We'd like to keep the mulch out there for the soybeans that come after," he said.
Hutchison's radishes have started to flower and he said Groff's team advised him that he could use herbicide before the viable seedpods had established to maintain good fields for no-till.
Dr. Ray Weil, environmental science and technology professor at University of Maryland, said the radishes will be an easy kill compared to tougher barassicas like rapeseed.
"The flowers will not germinate until late in the summer," Weil said. "Radishes are not very competitive in the spring."
"We want to avoid working it under, we need all the help we can get if it gets dry (this summer)," Hutchison said.
Mark Van Gessel, University of Delaware Extension weed specialist, said he had started running trials on the different types of herbicides to remedy the over wintering radish.
Van Gessel said it was "a little early to see which application was most effective" but he began testing because he had received lots of calls about it. He said he plans to continue the trials but most farmers will have to make a decision before he comes out with a definitive solution.
"Doing something is better than doing nothing," Van Gessel said.
Some radishes have grown quite large, and if they are not dealt with it could make "planting feel like you're running over top of baseballs and softballs," said Lewis.
R. Dave Myers, Anne Arundel County Extension ag agent said through his observations, Anne Arundel County farmers are planning to plant right through after burn down.
"Their biggest problems will be negotiating through bigger radishes," Myers said.
Most planters have row cleaners that push the radishes aside allowing for good seed placement of the cash crop, Myers said.
The brassicas should then rapidly decompose and will release soil nutrients for use by the emerging cash crop.
"The last six years have been pretty cold," Lewis said. "Over a 20-year average, it's been about a one in five chance (of radishes over wintering)," he said, suggesting that amending regulations to account for warmer winters could ease farmers' issues in the spring.
"If MDA could give us a good herbicide control program and in winters like this we can do something in December or January instead of March, we wouldn't have to worry," he said. "Discussions like this need to take place."
Weil said he hoped farmers would continue to take advantage of the cover crop despite the unseasonably warm winter.