A weed is undesirable because it disrupts the aesthetic appearance and potentially its durability. The best method of weed control is to prevent weeds from becoming established by following proper turfgrass establishment and maintenance practices. A dense turf has few weeds.
Turfgrass weeds can be divided into three categories based on the strategy for successful control.
Annual Grass Weeds
Summer annuals include grasses such as crabgrass and goosegrass. Annual bluegrass is an example of a winter annual. Most grass weed seeds require light for germination, thus a dense stand of turf, maintained at 4 to 4 1/2 inches, will reduce annual grass weeds dramatically.
A preemergent herbicide will also control annual grass weeds. With a pre-emergent, timing is critical. The herbicide must be applied before weed seeds germinate but very early application allows the herbicide barrier to degrade and lose its effectiveness. For summer annuals, apply a preemergent herbicide when the soil temperature at 2 inches is 55 degrees for three or four consecutive days (about when the forsythia bloom). Control winter annuals with a late summer to fall preemergent application, but this timing is trickier because winter annuals germinate over a long period each fall.
Due to their physical differences from grasses, broadleaf weeds such as chickweed, henbit, dandelion, and plantain can be controlled with selective herbicides. The common turfgrass herbicides include 2,4-D, MCPP and dicamba or a mixture of these three. Dicamba can injure surrounding trees and shrubs so avoid use near desirable landscape plants.
Perennial Grass Weeds
These weeds are no different from their desirable counterparts. Therefore, the only method of control is to hand-pull (removing the entire root system) or spot-treat with a non-selective herbicide such as glyphosate and reseed the affected area.