Dicamba labels allow use before, during, or after planting of grass crops including corn and wheat. Increasing prevalence of glyphosate-resistant kochia may influence growers to consider using sequential applications with residual soil activity of dicamba in their grass crop weed control strategies.
Spring Dicamba Application and Crop Planting Interval
Dicamba labels allow use before, during, or after planting of grass crops including corn and wheat. Increasing prevalence of glyphosate-resistant kochia may influence growers to consider using sequential applications with residual soil activity of dicamba in their grass crop weed control strategies. Kochia emerges early in the spring and if glyphosate and 2,4-D resistant biotypes are present there are few effective early-preplant burndown options available prior to planting broadleaf crops. Several people have inquired about the safety of soybean to dicamba residues in the soil from early preplant applications. The label gives the following information:
“Planting/replanting restrictions for Clarity applications of 24 fluid ounces per acre or less: No rotational cropping restrictions apply at 120 days or more following application. Additionally, for annual crop uses in this label including corn, cotton, sorghum, and soybean, follow the PREPLANT USE DIRECTIONS in section VI. Crop-Specific Information”
Preplant Applications:
Apply 4 - 16 fluid ounces of Clarity per acre to control emerged broadleaf weeds prior to planting soybeans. DO NOT exceed 16 fluid ounces of Clarity per acre in a spring application prior to planting soybeans. Following application of Clarity and a minimum accumulation of 1" rainfall or overhead irrigation, a waiting interval of 14 days is required for 8 fluid ounces per acre or less, and 28 days for 16 fluid ounces per acre. These intervals must be observed prior to planting soybeans or crop injury may occur. DO NOT make Clarity preplant applications to soybeans in geographic areas with average annual rainfall less than 25 inches."
The breakdown rate of dicamba would be slower in soils of the northern plains where soil temperature is lower and annual precipitation is less than in southern regions. This is a primary reason why dicamba has not been used nor recommended in North Dakota prior to planting soybean or other broadleaf crops. Studies will be conducted in 2014 and 2015 to observe the effect of different rates of dicamba on broadleaf crops planted immediately after application and also one year after application. With the registration of RU Xtend soybean in 2015 there will be concerns regarding broadleaf crop planting intervals following application of higher rates of dicamba than have not historically been used in North Dakota. We will continually update through <agdakota> list- serve the results of field studies.
Source : ndsu.edu