Selective Control of Annual Bluegrass in Cool‐Season Turfs with Fenarimol and Chlorsulfuron

Abstract

AbstractAnnual bluegrass (Poa annua L.) is a weed that presents turfgrass managers with serious problems upon infestation into desired turfgrass stands. This species can be managed as a turfgrass, but selective herbicides for its removal would be very useful in intensely managed turfs. In this study, fenarimol [3‐(2‐chlorophenyl)‐3‐(4‐chlorophenyl)‐5‐ pyrimidinemethanol] and Chlorsulfuron {2‐chloro‐N[(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐y1)‐aminocarbonyl]‐benzenesulfonamide} were tested in field and greenhouse trials over a 2‐yr period to determine their effectiveness as annual bluegrass (Poa annua L.) controls in both Kentucky bluegrass (Poa annua L.) and creeping bentgrass (Agrostis palustris Huds.) turfs. Fenarimol treatments in the field included rates of 0, 155, 306, 459, 612, and 765 g ha−1 applied eight times in 1984 until cumulative amounts of 1.2, 2.4, 3.7, 4.9, and 6.1 kg ha−1 were reached, and seven times in 1985 until cumulative amounts of 1.1,2.1,3.2,4.3, and 5.4 kg ha−1 were reached. In the greenhouse, fenarimol was applied at single application rates of 1.5, 3.0, 4.6, and 6.1 kg ha−1. Chlorsulfuron was applied in the field at single application rates of 18, 35, 70, 140, and 280 g ha−1 and in the greenhouse at single application rates of 70, 140, 210, and 280 g ha−1. Fenarimol was not effective in controlling annual bluegrass in the field or greenhouse and caused discoloration to the creeping bentgrass in the field at rates above 4.9 kg ha−1. Chlorsulfuron was effective in controlling all three annual bluegrass biotypes in the greenhouse and had no detrimental effects on creeping bentgrass or Kentucky bluegrass. In the field, Chlorsulfuron was effective in controlling annual bluegrass at one of the two testing sites.