By Tom Dominguez, Extension Service
For most areas early September is the time to be applying fall preemergents for the control of annual winter weeds in home lawns, sports fields and on golf courses.
One of the big reasons for poor weed control with the fall preemergent applications, is that individuals wait too late to make their treatments. Once the weed seed has germinated and the plant is growing, the majority of these preemergents will not control the weeds. The preemergents need to be applied before the weed seed starts to germinate.
Note, there are two exceptions to this. The preemergent herbicides Simazine and Kerb both have postemergent activity as well as preemergent activity. These two products can be applied after many of the winter weeds have already started to germinate and grow and still provide effective winter weed control. Many of the commercial lawn care companies and landscapers use these products in their program.
A second major reason for failure is not watering the herbicide in thoroughly. For these products to work, they need to be watered down into the top layer of the soil where most of the weed seed are germinating. Also, many of these herbicides are broken down by sunlight and if left on top of the turfgrass, they will loose some of their activity.
Preemergent herbicides are the most effective means for control of annual grassy weeds in turfgrasses. There is really not a real good option for controlling grassy weeds with a postemergent herbicide in the winter months.
If the turfgrass is completely dormant, then you can use herbicides such as Glyphosate (Roundup) or Glufosinate – ammonium (Finale) for winter grassy weed control.
However, for most of our winters, many of the turfgrasses being grown in home lawns and on sports fields and golf courses do not go completely dormant. Using one of these products when the turf is not completely dormant could cause severe injury to the turfgrasses.
Outlined below are some of the common preemergent herbicides being sold for use in turfgrasses.
These are products available to home owners. The list does not include commercial products commonly used by commercial operators, sports field managers and golf courses.
Note, some of these products may not be available in the different areas.
My recommendation would be to take the time to visit some of your local nursery and retail stores to see what is available in your area.
The information given herein is for educational purposes only. Reference made to commercial products or trade names is made with the understanding no discrimination is intended and no endorsement by New Mexico Cooperative Extension System and its agencies is implied.
Tom Dominguez is an agent with the Quay County Extension, NMSU Extension Service, He can be reached by emailing firstname.lastname@example.org or calling 461-0562.
Preemergent for homeowner use (nursery and retail outlets)
Company Trade Name Common Name
Green Light Amaze Grass and Weed Preventer benefin and oryzalin
Green Light Betasan Crabgrass Preventer bensulide
Vigoro Preemergent Crabgrass & Weed Control dithopyr
The Scotts Company Halts Crabgrass Preventer pendimethalin
PBI/Gordon, Inc. Betasan bensulide
Green Light First Down Granules benefin and trifluralin
Green Light Portrait Broadleaf Weed Preventer* isoxaben
Fertilome Fertilome Winterizer & Weed Preventer simazine