Pre-Emergent Weed Control
Pre-emergent weed control is the most effective strategy for the control of grab grass and other grassy annual weeds. It is also the most cost effective way to control weeds. Crab grass is one of the more difficult weeds to kill once it has established. If you apply a pre-emergent to the lawn early in the season it will prevent the crab grass seeds from germinating.
Timing is everything when it comes to applying a pre-emergent. The first application should be preformed in tandem with a fertilizer. This is usually the first application we apply in our fertilization and weed control program. This application needs to happen in the early spring before soil temperature reaches 55 degrees.
Conditions that will impact the effectiveness and duration of the pre-emergent is the amount of rainfall received and microbial activity in the soil. Heavy amounts of rain can dilute and wash the chemicals too deeply into the soil to be effective. Soil microbes as well as ultraviolet light can begin to breakdown the chemical barrier formed by a pre-emergent herbicide. As a result we always do a second application of pre-emergent weed control in the month of May. By doing this we are able achieve almost a 100% control of grassy weeds, minimizing the use of post emergent herbicides.