Cellular response of two turfgrass cultivars to selected herbicides

Root meristem cell, foliage, and root growth responses of Penncross creeping bentgrass (Agrostis palustris Huds.) and Tifgreen bermudagrass [Cynodon dactylon (L.) Pers. x Cynodon transvaalensis Burtt-Davy] to postemergence herbicides in solution culture were investigated with visual ratings, root and shoot ash weights, paraffin sections and photomicroscopy. The capacity of these cultivars to recover from herbicide injury was evaluated. Bentazon [3-(l- methylethyl)-(IH)-2,1,3-benzothiadiazin-4-(3H)-one 2,2- dioxide] and bromoxynil (3,5-dibromo-4-hydroxybenzonitrile) treatments resulted in reduced shoot and root weights of both cultivars. Cellular manifestations of herbicide injury were not easily detectable. Severe reductions of shoot and root weights of bentgrass and bermudagrass were noted for treatments of asulam [methyl[(4-aminophenyl)sulfonyl] carbamate] and sethoxydim [2-[l-(ethoxyimino)butyl]-5-[2- (ethylthio)propyl]-3-hydroxy-2-cyclohexen-l-one]. Prolific lateral root initiation abnormally close to root tips of bentgrass was induced by asulam. Bentgrass plants were killed following treatments of asulam and sethoxydim. Pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynl)benzamide] exposure killed test plants of both cultivars.