Share Facebook Twitter Google + LinkedIn Pinterest We heard recently that there is as yet no approval or plans to sell the new soybean herbicide technologies for 2016. Some of you have been waiting for this miracle of science to bail you out of your weed resistance problems. Sale of dicamba or 2,4-D resistant soybeans will probably not happen until 2017 on a large scale. What we do have is the possibility of better management from you — the person who sets the weed control program on your farm. Many of your neighbors have found the solution to managing resistant weeds. You need to ask them for tips, all of which likely came originally from OSU’s Mark Loux.Marestail has two primary periods of emergence — from late summer into fall, and from late March through June. But we learned this year that marestail can germinate almost any time. We tend to think that spring-emerging marestail was the most problematic to manage. In years when I have seen a dry August, we tend not to have a lot of late summer and fall emergence which means we will probably have a shift to more spring emergers, or it will rain throughout October and flush all the seeds into the system as fall emerging marestail.Here’s the fall management suggestion:Start with a fall herbicide application — this is an integral part of marestail management. The primary role of the fall treatment is to remove the marestail plants that emerge in late summer and fall, so that the spring herbicide treatments do not have to control plants that have overwintered.An effective fall treatment results in a weed free seedbed in early spring, and more flexibility for the spring burndown/residual treatment timing. Marestail plants are small in the fall, and easily controlled with 2,4-D.No one I have talked with was ever sorry they spent money on fall applications.In the spring you’ll need to apply another burndown and make the application of an effective pre-emergent herbicide.Giant ragweed populations with resistance to glyphosate can occur in Ohio and appear to be increasing. Some populations have resistance or a high tolerance to both glyphosate and ALS inhibitor herbicides. Postemergence control of these populations in soybeans can be extremely difficult, and the most effective management strategy may be to plant corn. It is essential that no-till soybean fields with resistant populations receive a preplant treatment of 2,4-D ester, to ensure that that the field is weed free at the time of planting. This would be following your fall burndown application if you have marestail and the one when you apply residual herbicides.Include residual herbicides in the preplant burndown treatment (or apply these after planting where tillage is used), which involves the use of Scepter or a product containing chlorimuron or cloransulam.These herbicides will reduce the giant ragweed population and slow the growth of remaining plants to build more flexibility in the postemergence application window. None of these herbicides will control ALS-resistant giant ragweed, however.Use of Liberty in Liberty Link soybeans is still the most effective tool for management of glyphosate-resistant giant ragweed populations. OSU and Purdue research has shown that glyphosate- and ALS-resistant populations can also be managed with multiple applications of PPO inhibitors (such as Flexstar, Cobra), although this approach may lead to the development of resistance to these herbicides as well.And yes, new technology is coming, sometime, but it will still require good management and the application of a pre-emergent herbicide. Learn now and continue to implement those skills.Other updates are posted on the Weeds webpage: http://agcrops.osu.edu/specialists/weeds, particularly view the Site of Action videos under multi-media. The weed science weed team also has a blog where they post some good videos: http://u.osu.edu/osuweeds/.