Q&A About Crabgrass & Quackgrass
Crabgrass is an annual grass type weed that appears above the soil in July and August. It is often confused with quackgrass which is a perennial grass type weed that appears in the lawn in April and May. Crabgrass is a very difficult weed to control. Crabgrass can be treated both pre-emergently, which are treatments applied before the weed appears above the surface, and post-emergently, or after the weed appears.
Guaranteed TurfCare has developed effective treatment schedules for Crabgrass that consists of multiple pre-emergent and post-emergent treatments. We call this service "Crabgrass Plus".
Common Consumer Questions About Crabgrass
Why is Crabgrass so difficult to control? Crabgrass cannot be controlled as effectively after the plant has emerged like broadleaf weeds can. As a result, one needs to rely heavily on pre-emergent treatments for a control program. Unfortunately, a pre-emergent application does not offer complete control.
How does a pre-emergent application work? The pre-emergent treatment, when watered into the soil, forms a partial barrier in the top 1/8" to 1/4" of the soil. If the sprout, from the newly germinated seed, makes contact with the herbicide in the soil, it will die before emerging above the ground.
Why are the results of a pre-emergent application somewhat unpredictable? There are several factors that can reduce the odds of a germinated weed sprout making contact with the herbicide in the top 1/8" of the soil. They are as follows:
- Some of the herbicide dissipates into the air before it is watered into the soil.
- The herbicide binds to the thatch and never reaches the soil
- Over a matter of weeks, the soil gradually reduces the herbicide to zero effectiveness.
What does Guaranteed TurfCare do to improve the results? To improve the odds of germinated weed sprout making contact with the herbicide in the soil, you need to apply more than one application. Two pre-emergent applications spaced 4 weeks apart, prior to July 1, will improve control. Post-emergent treatments applied directly to the emerged crabgrass plants in July will also be necessary. Additional pre-emergent treatments in July will help reduce August infestation levels. All of these additional treatments are part of our "Crabgrass Plus" program.
Why do I have so many weeds along the edges of the street and driveway? We call these heat-sink areas. The extra heat generated by the blacktop and concrete warm the soil, which germinates a higher percentage of weed seeds. The increased heat also stresses the turf, reducing turf density. Reduced turf density allows more sunlight to the soil, which also increases the weed seed germination rate.
The only solution is to re-establish a dense turf with a very aggressive watering program to keep the soil cooler.
Can I plant grass seed before or after a pre-emergent crabgrass treatment? You should not seed before a pre-emergent treatment, however, you can do some spot seeding after a pre-emergent treatment if you use new topsoil and seed into it.
When can I water, mow, or rake after a pre-emergent treatment? Wait 24 hours (to protect any broadleaf treatments), then water thoroughly before mowing or raking. Watering is necessary to improve the results of fertilizer and pre-emergent treatments.
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