Agricultural News
OSU Extension Provides Multiple Ways to Control Weeds in Sesame
Tue, 07 Jun 2011 15:01:49 CDT
Sesame is an increasingly popular option for Oklahoma producers looking for a rotational crop that can handle hot, dry summers. Currently, herbicide options for sesame production are limited. However, through a combination of herbicides and a vigorous, competitive crop, it is possible to produce high-quality sesame.
Preplant and burndown weed control
Because of its slow initial growth, sesame will not compete with early-season weeds and stands can quickly be lost due to over-growth of weeds. Therefore, it is very important to start the growing season with a clean, weed-free field. For broad-spectrum weed control, several glyphosate products are labeled for pre-plant applications and can be used any time prior to sesame planting. Sesame is very sensitive to glyphosate and should not be used after planting, unless the seed is adequately covered with soil.
For no-till production, 2,4-D can be added to glyphosate to improve control of many broadleaf weeds, such as marestail or pigweed. However, like many other sensitive crops, sesame should not be planted immediately after spraying 2,4-D. Previous research conducted by OSU and in Texas indicates that 2,4-D should be applied at least 2 weeks prior to planting. Other burndown herbicides, such as Sharpen®, should not be used prior to planting sesame.
Preemergence weed control
Currently, the only herbicide registered for preemergence use in sesame is Dual Magnum®. Dual Magnum should be applied at a rate of 0.67-1.33 pints/acre after planting but before sesame emergence. For maximum weed control, the higher rate should be used. Dual Magnum is effective on many grass and small-seeded broadleaf weeds, such as pigweed and kochia. It is important to remember that Dual Magnum does not have any postemergence activity; therefore, if any weeds are present, it is necessary to use glyphosate or tillage to control them prior to planting. Due to the lack of postemergence herbicide options, it is very important to use Dual Magnum as a preemergence treatment.
Postemergence weed control
The only postemergence herbicide options currently available for sesame include Select®, Select Max® and other products that contain clethodim as their active ingredient (for example, Shadow®, Volunteer®, Arrow® and several others). These products will only provide control of grass weeds and do not have any activity on broadleaf weeds. Because of the lack of postemergence herbicide options for broadleaf weeds, it is necessary to use Dual Magnum® as a preemergence treatment. Select®, Select Max®, and other products that contain clethodim must be applied before the flowering stage of sesame. If these products are applied during flowering, these flowers will not produce capsules and, as a result, yields will be reduced. This injury is known as "cap gap" and is easily recognizable by the lack of seed capsules on the stem. Research conducted by OSU in 2010 showed yield reductions of nearly 30 percent when sesame was treated with Select Max® during flowering compared to the untreated check, due to fewer capsules formed on the stem.
Thanks to Joe Armstrong, Extension Weed Specialist at Oklahoma State Univeristy, for this article over sesame.
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