Impact of mowing and weed control on broadleaf weed population dynamics in turf

Various turf management activities may influence weed population dynamics and interfere with weed control. The effects of a biocontrol agent, Sclerotinia minor, a chemical herbicide, Killex (TM), and mowing height on broadleaf weed dynamics were examined in two turfgrass stands for two consecutive years. Mowing did not reduce the population densities of dandelion or the ground cover of broadleaf weeds. In the second year, mowing significantly reduced white clover density, but significantly increased broadleaf plantain density, particularly at the closest mowing height (3-5 cm). Apart from the close height, the S. minor and Killex (TM) treatments were equally effective in suppression of dandelion, white clover, broadleaf plantain, and prostrate knotweed in the second year. Common mallow increased in the herbicide treated plots and other species including yellow woodsorrel, yellow toadflax and lambsquarters increased in abundance in plots mowed at the 3-5 cm height and in plots treated with Killex (TM). Significant differences between the Killex (TM) and S. minor treatments on dandelion population dynamics were rarely present and did not favour either treatment. S. minor did not damage the turfgrass, but Killex (TM) reduced turf quality in 25% of the plots. The application of S. minor with a regular, medium height (similar to 7 cm) mowing regime was highly effective in controlling broadleaf weeds in temperate Kentucky bluegrass turf.