Herbicides for Establishing Kentucky Bluegrass Turf from Plugs 1

The use of herbicides for controlling weeds while establishing turf from seed has been limited by the intolerance of seedling turfgrass plants to many herbicides. However, the introduction of vegetative techniques tor establishing Kentucky bluegrass has presented new possibilites for successfully using herbicides in conjunction with turfgrass establishment. The purpose of this study was to determine whether the use of preemergence herbicides is feasible while establishing Kentucky bluegrass from plugs. Greenhouse studies were undertaken to evaluate the effects of preemergence herbicides on the growth of single‐plant cultures of ‘A‐20’ Kentucky bluegrass ( Poa pratensis L.), All herbicides inhibited some aspect of growth as determined by measurements of roots, shoots, density, and rhizomes. In the field, however, only benefin (N‐butyl‐N‐ethyl‐ a,a,a‐trifluoro‐2,6‐dinitro‐ p ‐toluidine) and bensulide [ O‐O ‐diisopropyl phosphorodithioate S‐ester with N‐(2‐mercaptoethyl)benzene sulfonamide] reduced the lateral growth of ‘A‐20’ plugs while calcium arsenate and DCPA (dimethyl tetrachloroterephthalate) did not inhibit establishment of the turf compared to untreated plots. Where annual bluegrass ( Poa annua L.) was seeded in conjunction with plugging the fastest Kentucky bluegrass establishment and best weed control were in plots treated with oxadiazon [2‐tert‐butyl‐4‐(2,4‐dichloro‐5‐isopropoxyphenyl)‐ Δ 2 ‐l,3,4‐oxadiazolin‐5‐one]. Postemergence applications of endothall [7‐oxabicyclo(2,2,l)heptane‐2,4‐dicarboxylic acid] did not control annual weeds and reduced the amount of ‘A‐20’ in some plots due to its injurious effects on the plugs.