Watch out for “Hardened Off” Weeds

BY Dairyland Seed Agronomy Team

As planting progresses and finishes across the Dairyland Seed footprint, herbicide applications will begin for the season. Warmer weather is here, so more favorable growing temperatures means that crops and weeds alike will be growing rapidly in the coming weeks.

There are areas within our footprint experiencing drier conditions. These dry conditions, coupled with rising temperatures, can make weed control more difficult due to weeds “hardening off”. Weeds or plants that “harden off” are going into defense mode to protect themselves from stress. These plants form a thicker cuticle (which is the outer layer of leave tissue) to conserve moisture in the plant. If stress continues, these plants can lower respiration rates which can hinder growth but can make the weeds more difficult to control with herbicides. The following are some tips for herbicide applications in these stressed environments.

Ensure proper mixing order of herbicides. This can ensure full efficacy of the herbicides applied and increase weed control by avoiding antagonism or tie up in the spray solution.
Make herbicide applications during less stressful times of day. Applications made early in the day when temperatures are cooler are less stressful for weeds and crops alike. This can improve herbicide uptake by weeds and allow the crop to metabolize the herbicide easier reducing the chance of crop injury.
Proper use of water conditioners and adjuvants. Applying adjuvants, such as crop oils or surfactants, according to specific label recommendations can help improve herbicide efficacy during stressed periods as well. It is important to note that the use of these additives can increase the risk of negative crop response or “dinging” the crop. Adjuvants increase herbicide efficacy by allowing the herbicide to enter the plant more easily.

It is important to note that only certain areas of the Dairyland Seed footprint are experiencing these stressed conditions at this time. If you have questions regarding this topic, contact your local Dairyland Seed DSM or Regional Agronomist.