We know spring is on its way when the pre-emergent discussion has started. What should you know or remember about pre-emergent to make applications a worry-free process? We’ll tell you here.

Two of the most popular pre-emergent products out there today are prodiamine and dithiopyr. You can apply prodiamine and dithiopyr in the spring or fall; however, spring is the traditional time to put them down. You want to apply pre-emergent, historically, around the same time as the forsythia blooms in the spring (mid to late April in Central Indiana). Now, you can also use the growing degree day model to help you know when the best time to apply would be in your area. Check growing degree days with www.gddtracker.net.

Prodiamine prevents seeds from germinating, thus, it needs to be applied before crabgrass seeds germinate. If you put prodiamine down after the seedling has developed into a small plant, it will not work.

Dithiopyr will not only give you pre-emergent control by preventing seeds from germinating like prodiamine, but it will also provide you with post-emergent control of crabgrass to the first tiller (fifth leaf) stage of growth.

If you are in an area where, historically, the summer is pretty hot, you may want to split apply pre-emergent. A very hot summer can break down the chemistry quicker, and cause the products to not last as long. Split apply in April/May and then at the end of June for control.

In the late fall/early winter, apply prodiamine and dithiopyr once the soil temperatures are at or below 50 degrees (but not at freezing). The spread rate is a minimum of 175 lbs per acre and the higher rates are needed due to break down with microbial activity. Active ingredients per acre vary with geographic location. Be sure to apply the correct active ingredient for your area. Note: Good for low-budget clubs, which do not have an abundance of labor. When the fall timeframe is used, spring applications are not needed. Find more information on the fall application time here.

If goosegrass is also a concern for you, Ronstar is your answer. It is a great pre-emergent for goosegrass control. One thing to note about Ronstar: only the granular form can be used on cool-season turf. Ronstar, also, needs to be put down when it is still cool in the spring, preferably mid-April.

For more information on prodamine, dithiopyr, and Ronstar, contact your ATS sales representative.