Alan Smock says their biggest challenge in farming the Vincennes University at Jasper Campus farm in 2012 was marestail, also known to some as horseweed. They are hoping to turn the farm in to a showcase for conservation practices that control soil erosion and protect water quality. Smock is a member of the Dubois County Soil and Water Conservation District that is managing and farming the land around the VUJC site.
Marestail took its toll, he said. They didn't realize that marestail had such a strong hold on that land, and it took over on part of the farm late in the season. Obviously they hope to rectify that this season. The land will be no-tilled.
Joseph Petrosino, an agronomist with Stewart Seeds, Greensburg, says that the temptation if you haven't applied a burndown by now is to leave out the 2,4-D. Otherwise they have to wait a week before planting soybeans after applying 2,4-D.
The risk, he says, is huge. Much of the marestail is glyphosate-resistant. If you're just getting in now, it's already bigger than you would like to spray it. What will likely happen is you will have a bunch of escapes and a situation similar to what Smock and the Dubois SWCD saw last year.
Instead, the agronomists suggests burning down with 2,4-D and waiting the week to plant. Suppose you can get it applied this week. You could still be planting legally by May 15. While tests have shown that soybeans respond to early planting too, the yield loss planting as late as May 26 is estimated at 7 bushels per acre on average.
"Even if you wait two weeks for the coast to clear after a high rate of 2,4-D, you may lose 7 bushels per acre if it pushed you back to late May," the agronomist says. Data from Ohio State University says not controlling marestail can cost you 8 to 14 bushels per acre. The agronomist believes applying 2,4-D and waiting will be an economical win in the long run.