Phytotoxicity of Herbicides to a Penncross Bentgrass Green

Abstract

A ‘penncross' bentgrass (Agrostis palustris Huds.) golf-type green was treated in the spring with seven herbicides at three rates each for three consecutive annual applications to assess their phytotoxicity. Herbicides which caused slight foliage injury the first year were tri-calcium arsenate, dimethyl tetrachloroterephthalate (DCPA), and polychlorodicyclopentadiene isomers (bandane); moderate injury occurred with 2,6-di-tert-butyl-p-tolyl methylcarbamate (terbutol) and N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine (benefin). No injury was observed with O,O-diisopropyl phosphorodithioate S-ester with N-(2-mercaptoethyl)benzenesulfonamide (bensulide) and 1-(2-methylcyclohexyl)-3-phenylurea (siduron). For the second and third year bandane was reapplied at half and tri-calcium arsenate at one fourth the original rate. Loss of bentgrass sod the second year was slight with terbutol and bandane and moderate with benefin and DCPA. No sod loss occurred with tri-calcium arsenate, siduron, and bensulide. Sod loss the third year was slight with tri-calcium arsenate, moderate with siduron and DCPA, and severe with bensulide, benefin, bandane, and terbutol. A persisting sod loss the fourth season, an observation year, was nil with tri-calcium arsenate; slight with siduron, benefin, and DCPA; slight to moderate with bensulide; moderate with bandane; and severe with terbutol.