When to apply Pre-Emergent?

This is a question that seems to come up almost everyday. Usually the question on when to apply pre-emergent this time of year is related to crabgrass and summer weeds. Researchers at the University of Maryland determined that the minimum daytime soil temperature to observe the initial emergence of crabgrass was 54 degrees. The major emergence of crabgrass, however, did not appear until soil temperatures were at least in the range of 60 to 70 degrees.  Around northeast Atlanta, the soil temperatures have been between 47-55 degrees the past week.  The optimum time to apply pre-emergent differs for each location depending on shade, soil type, moisture, etc. 

The earlier you apply pre-emergent the better control you may have initially, but more weeds could develop later in the summer if you do not come back again with another application.  If you apply it later, weeds may germinate before to you put it down causing a need for a post-emergent herbicide. 

With all this information, The golf course maintenance staff at Bears Best will be spreading our pre-emergent in the next 7-21 days depending on what the weather does during that time period. If it stays warmer and the soil temperatures continue to rise, we will apply it sooner rather than later. Here is a link to the risk levels of crabgrass provided on Syngenta's website. http://www.greencastonline.com/PestOutlooks.aspx?po_id=47