Issue No. 18, Article 7/July 24, 2009
Preharvest Intervals for Postemergence Soybean Herbicides
Most postemergence soybean herbicide labels specify a preharvest interval or a soybean developmental stage beyond which applications should not be made. Labels of some products, such as Pursuit and Extreme, indicate both a developmental stage (before soybean bloom) and a preharvest interval (85 days).
Preharvest intervals indicate the amount of time that must elapse between herbicide application and crop harvest. These intervals are established to allow sufficient time for the herbicide to be broken down or metabolized in the plant. Additionally, the preharvest interval reduces the likelihood of herbicide residues remaining on the harvested portion of the crop. Failure to observe the preharvest interval may result in residue levels in the crop that exceed established limits.
There also are restrictions on many postemergence soybean herbicide labels about whether the soybean crop may be used for livestock feed or if treated fields may be grazed as forage. Table 1 details preharvest intervals and grazing restrictions for multiple postemergence soybean herbicides.--Aaron Hager