Spring is just around the corner; birds are singing, tulips have emerged, trees are budding out, and the turfgrass is greening. Last year at this time I was getting ready to apply a preemergence herbicide to control the crabgrass in my lawn. But, does this mean now is the time to apply a herbicide this year? No!, even though spring fever has hit everyone, including myself, restraint is necessary, because we are experiencing a late spring warm up. This slow warming of the soil means the germination of crabgrass will also be delayed unless we receive some very warm, sunny days in the next couple of weeks.
The reason for the crabgrass delay is because this annual plant germinates when the soil temperature reaches about 60 F. Seeds require warm, moist soil conditions and light for germination. Once the seed has germinated, the plant quickly becomes established and usually out-competes your cool-season turfgrasses during the stressful summer. If uncrowded and undisturbed, a single plant may easily cover 6-10 feet in diameter. Plants are prolific seed producers in that a single plant can produce up to 150,000 seeds before a killing fall frost.
This article originally appeared in the April 14, 1993 issue, p. 48.
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