Plan Ahead To Manage Weeds In Variable Weather

JOE BUNCK

EVEREST, KAN.
   Herbicide performance can be affected by the environment before, during and after application. It’s easy to stick with a weed control plan when the season is going well and the weather cooperates, but it’s also important to plan for challenging weather conditions.
   A wet spring will alter weed management plans by putting a stop to tillage or early season herbicide applications. When control applications are delayed, weeds will continue to grow and management plans may need to be altered to provide satisfactory control. New herbicide technologies from Bayer Crop Science Division can be used for control of weeds in the field around the time of planting and after the crop has emerged. Channel Seedsmen conduct Field Check Up Series visits to identify weed populations and work with farmers to help determine the best herbicide products for each field.

   Under drought conditions, generally fewer weeds germinate due to dormancy mechanisms that inhibit sprouting in inhospitable growing conditions. Weeds that do germinate often have a harder time establishing. Timely rains allow weed seeds to germinate, and those that emerge in low spots that hold water longer may be more resilient with less competition from other weeds.
   Weeds growing in drought conditions are often harder to control than weeds growing in wetter environments because physiological plant processes, photosynthesis, translocation and growth are all slowed and herbicides may not be metabolized. In drought conditions, herbicides are more effective on weeds smaller than 3 inches tall. Spraying earlier in the day helps boost herbicide efficacy before the heat of the afternoon causes plant physiology to slow down to conserve water.
   As planting season gets underway in Kansas farmers should consider scheduling their post herbicide application based on planting dates of individual fields, 21 days after planting is an optimum time to apply the post herbicide. Emerged weeds at planting may be larger than 4 inches after three weeks and thus become harder to control.
   Balancing the drive for high crop yields with weed control solutions and timely planting can be a challenge when dealing with unpredictable spring weather. Fortunately, new herbicide products from Bayer Crop Science Division are helping farmers stay flexible when weed control plans have to change. See your Channel Seedsman or visit Channel.com for more information about weed control. ∆
   JOE BUNCK: Channel Technical Agronomist