Crabgrass can certainly prove to be a worthy opponent to any homeowner with the goal of keeping their lawn looking its best all season long.
When Ben Franklin said, “An ounce of prevention is worth a pound of cure”, he probably wasn’t referring to this mid-summer annual weed but, nonetheless, his words surely do apply.
Knowing your rival
Crabgrass is classified as an annual grass weed. These are weeds that germinate from seed, grow vegetatively, produce seed and die within a 12 month period. Although crabgrass seems to be the most common, other annual grass weeds that routinely invade Ohio’s turfgrass areas are goosegrass, foxtail, barnyardgrass, and annual bluegrass.
Pictures #1 and #2 show two forms of crabgrass commonly found in lawns. Picture #3 shows a patch of tall fescue in a bluegrass lawn.
Tall Fescue is commonly mistaken for crabgrass because of its unsightly appearance in an otherwise uniform lawn. The control method for Tall Fescue is much different than that of crabgrass- A subject that we will discuss in another blog later in the year.
Your best line of defense
Although it is possible to treat crabgrass reactively, the pro-active approach is by far the recommended plan of attack for this battle. This pro-active approach should include a crabgrass pre-emergent. Although there are several different products on the market, they all essentially work the same way- by creating an invisible “shield” in the top layer of the soil that prevents the crabgrass from germinating. Now that we have the mental image of this shield, we can understand why it is important not to puncture the shield by aerating or de-thatching after the pre-emergent has been applied.
It is also important to note that this pre-emergent will also prevent grass seed from germinating in the spring.
Beating it to the punch
Crabgrass will begin to germinate when average daily soil temperatures reach approximately 55-60° F. The timing of the application of the pre-emergent herbicide is critical because, in most cases, once this weed has germinated you’ve already lost round 1 and will have to take a reactive approach.
With any lawn care program, the ultimate goal should be to thicken the lawn to the point that it acts as its own natural defense against invading weeds. A lush healthy lawn will shade the soil and choke out emerging crabgrass and broadleaf weeds. Good cultural habits including irrigation and proper mowing will dramatically help your lawn be the greener one on the other side.
DO’S AND DON’TS of Crabgrass Prevention