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Looking for Options to Control Weed Escapes? Consider Your Inter-Row Cultivator (07/04/19)

Your row crop fields look good. Stands are excellent and the crop is uniform. Weed control, for the most part, is excellent.

Your row crop fields look good. Stands are excellent and the crop is uniform. Weed control, for the most part, is excellent. However, there are some weed escapes, perhaps herbicide resistant weeds in the field. Weeds are pushing 12-inches tall but there are not that many of them. However, you know failure to remove weeds will result in seed rain and potentially more weeds in the following season. What are my options?

•     Postemergence herbicides often are not a feasible option. Escaped weeds usually are too big to spray and likely will not be controlled with most postemergence herbicides, especially contact herbicides. And a repeat application of the herbicide you used previously will not work on herbicide resistant weeds.

•     Hand labor.  An excellent choice depending on the availability of labor, the size of field or the level of weed infestation. Sugarbeet growers participating in the annual survey of production practices at the 2018 Willmar, MN technical seminar reported the average cost of hand-labor ranged from $10.00-20.00 per acre.

•     Consider your inter-row cultivator. Its equipment you already own and have experience operating. Research conducted at NDSU in 2017 and 2018 reported inter-row cultivation removed at least 65% of emerged waterhemp escapes from postemergence herbicide application. But does cultivating do more harm than good? Producers asked if cultivation a few weeks after applying chloroacetamide herbicides postemergence to sugarbeet and preemergence to waterhemp to remove herbicide-resistant waterhemp would be effective without reducing the efficacy of their layby herbicides and without stimulating another flush of weeds. Cultivation timed near sugarbeet canopy closure interfered with waterhemp growth and allowed the crop canopy to suppress further emergence. However, we found a different result with escapeed lambsquarters. Escapes occurred earlier in the season (since lambsquarters germinates and emerges earlier in the season) and cultivation stimulated further lambsquarters germination and emergence, especially following a rainfall event or in an open canopy. In sugarbeet, a repeat glyphosate-application provided nearly 100% control of common lambsquarters , even when the lambsquarters plants were 8-12 inches tall.

 

Tom Peters

Extension Sugarbeet Agronomist

NDSU & U of MN

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