By Gay Wilhelm, Master Gardeners of Placer County
Q: Crabgrass is spreading in my lawn. What can I do to stop it?
A: Who hasn’t done combat with crabgrass? What a foe! But there is help.
There are two kinds of crabgrass in California, smooth crabgrass and large or hairy crabgrass. Smooth is usually shorter and more common in turf grass. Large crabgrass can grow up to 2 feet and is more common in ornamental landscapes. However both are spread by seeds and from rooting of the nodes that lie on the soil. Therein lies the problem.
When digging out the pest you need to get all those nodes for if they break off another plant will take root.
Your first defense is to look at your cultural practices of your lawn maintenance. Vigorous growing lawns can combat an invasion of crabgrass. Crabgrass is not very competitive. Proper height when mowing, depending on the species is very important. Fertilization when actively growing will crowd out seedlings of crabgrass. Turf grasses adapted to your area will also increase vigor. Watering practices are also important. Overwatering or light daily irrigations can make turf more susceptible to invasions. Infrequent deep watering will lead to a healthier turf.
Crabgrass can be controlled with chemical herbicides. Using a pre-emergent in mid to late February will help prevent germination of seeds. Post-emergent herbicides can be used after crabgrass is established. Be sure to read the label to make sure that the product can be used on your type of turf grass. It is more effective when the crabgrass has only a few leaves. If the temperature is over 95 degrees, do not use herbicides as the turf may be damaged.
Sound like a war? These combatants are fierce but armed with determination I’m sure you are up to the challenge.
References: ipm/ucdavis.edu, “Crabgrass, Home and Landscape”.
More information regarding crabgrass can be obtained from University of California Statewide Integrated Pest Management website.