Now is the Time to Apply Pre-Emergent

If you are interested in controlling annual bluegrass, rescuegrass, henbit, and chickweed (winter annual weeds) in your lawn this winter, apply pre-emergent herbicide in early Sep.  If you are interested in controlling sandbur, goosegrass, and crabgrass (summer annual weeds), apply pre-emergent herbicide in early February.  

If you would like more information on pre-emergent herbicides you can contact the County Extension Office.  Apply these products like a fertilizer according to the directions using a rotary spreader.  Uniform coverage (apply in 2 perpendicular directions) is very important to prevent weed escapes.  Some of these products will stain concrete, so make sure you blow it off your driveway when you are finished.  It may also stain on your pants' leg and spreader.  The product needs to be watered in with a 1/2 inch of water (run the irrigation until several tuna cans laid out randomly in the lawn are half-full).

The product will control winter annual weeds when applied in September and summer annual weeds like field sandbur when applied in February before the weed seeds germinate.  It will not control perennial weeds like dandelion that come back from vegetative structures.  The costs for these products will be around $26.00 per 12,000 ft.

Be careful putting herbicides on St. Augustinegrass.  The fewer herbicides placed on St. Augustinegrass the better.  Even if St. Augustinegrass is on the label, it may still be stunted for a month or more.  Fall pre-emergent herbicide applications for winter annual weed control (henbit, chickweed, annual bluegrass) are safer on St. Augustinegrass than spring applications, but they control different weed spectrums.  One can use the rest of the bag the next season.  The active ingredient can stunt root growth. 

Do not apply the product anywhere you plan to plant seeds like vegetables or flowers or have wild flowers.   You may need to apply again in July, but hopefully, a dense, aggressive turf will prevent sunlight from reaching the soil and stimulating summer annual weed seeds to germinate and a second application will not be necessary.

It is too early for nitrogen fertilizers, so do not apply a pre-emergent herbicide on a nitrogen fertilizer carrier.  A good winterizer is high in potassium and iron with little nitrogen (5-0-31).  Apply the nitrogen once a month starting in April; May would be better if you can be patient.  You may just be fertilizing winter annual weeds.  The more nitrogen fertilizer one adds, the more often one should mow.  If one cannot mow more often than once a week, then use nitrogen fertilizer more sparingly.  Always maximize the amount of slow release nitrogen and iron in the fertilizers for lawns.  More is not better.

The most effective change in management most home owners can make is to raise the height of their mower to the highest setting and mow regularly (only cut 1/3 of the blade off) (stop wheelie mowing).  Turf mowed regularly at a high setting will have longer roots and a closed canopy which will shade the soil, save water, and not stimulate weed seeds to germinate.

For more information please call the Wise County Extension office at 940-627-3341