Crabgrass can be one of the most difficult weeds to control. There are many factors involved with controlling crabgrass using preemergent herbicides. These include herbicide selection, application rates, soils, cultural practices, environmental factors, and most importantly, timing.
Preemergent herbicides are applied prior to weed seed germination and post emergent herbicides are applied to actively growing weeds after weeds emerge. Most preemergent herbicides are characterized by very low water solubility. When properly applied, liquid preemergent herbicide forms an herbicide barrier. Once the emerging seedling’s tap root hits the barrier, the weed dies without injuring existing plants.
Granular preemergent herbicides control weeds through creating a barrier and volatilization. The active ingredient releases from the granule in a liquid and gaseous state and attaches to soil to fill the voids between carrier granules and complete the barrier. Herbicides with lower solubility and volatilization characteristics can have a less complete chemical barrier increasing weed break through potential.
Use the charts below to optimize crabgrass control, improve chances for success and help troubleshoot potential failures.
Maximizing Preemergent Herbicide Performance The best defense against turf weeds is a thick healthy lawn. Review your customer’s lawn health using the fundamentals guide below and address issues as needed before applying preemergent.
Another tool to determine the optimal timing for a pre-emergent herbicide application is the GDD (Growing Degree Days) Tracker. Enter your zip code and this tool will calculate the ideal range of dates to apply pre-emergent product in your area. This tool will adjust to the climatic changes from year to year.
Preemergent herbicides typically have longer residual properties than post-emergent herbicides, providing several months of control after application. LESCO preemergent control products are formulated based on proven science and engineered to work the first time, every time. Visit your local SiteOne or contact a LESCO representative to learn more about preemergent offerings.