| Abstract/Contents: | Three commercially available and four experimental herbicides were applied in several rate combinations at various times and evaluated for preemergence control of goosegrass (Eleusine indica (L.) Gaertn.) in an annual bluegrass (Poa annua L.) and Kentucky bluegrass (Poa pratensis L.) turf. Experimental design was a randomized complete block with three replications and an individual plot size of 6 by 10 feet. materials tested were bensulide (2.6G)27 ((O,O-diisopropyl phosphorodithioate) S-ester with N-(2-mercaptomethyl)benzensulfonamide), benefin (2.5G) (N-butyl-N-ethyl-a,a,a-trifluoro-2,6-dinitro-p-toluidine), oxadiazon (2G) (2-tert-butyl-4-(2,4-dichloro-5-isopropoxy- pheynl)-delta2-1,3,4-oxadiazolin-5-one), butralin (2.3G and 2G with fertilizer) (4-(1,1-dimethyl ethyl)-N-(1-methylprop- yl)-2,6-dinitrobenzenamine), DCPA (75WP) (dimethyl 2,3,5,6- tetrachloroterephthalate) and siduron (50WP) (1-(2-methyl- cyclohexyl)-3-phenyl urea). The butralin 2.3G with fertilizer material contained 20-5-7 fertilizer and at 4 lb/A applied 1.2 lb N/1000 sq. ft. Plots were located on a sassafras silt loam on the 6th fairway of Green Hill Yacht and Country Club, Green Hill, Maryland. The fairway was mowed at a one inch mowing height and had a pH of 5.2 and organic matter content of 1.8%. Herbicides were reapplied at various rates on initially treated areas. Initial treatments were applied on April 2 with follow up treatments applied on May 7 and July 9, 1975. Plots were evaluated for goosegrass control, turfgrass injury, residual toxicity to fall germinating annual bluegrass and turfgrass quality. On July 9, 1975 stress on Kentucky bluegrass and annual bluegrass turf was noticeable from April 2, 1975 applications of bensulide (3.6G) at 20 lb/A, butralin (2G with fertilizer) at 6 and 8 lb/A, and siduron (50WP) at 12 lb/A. Butralin (2G with fertilizer) produced stress on Kentucky bluegrass with split applications of 4 lb/A in April plus 2 lb/A in May (4 + 2 lb/A) and 4 + 4 lb/A in April and May. On September 26, 1975 excessive stress was still noticeable on the Kentucky bluegrass and annual bluegrass turf from single applications of bensulide applied at 15 and 10 lb/A in April and combination treatments of 10 + 5 + 5 lb/A in April, May and July, 10 + 5 lb/A in April and May, 10 + 5, 15 + 5 and 20 + 5 in April and July respectively. In this instance split rates did not seem to significantly reduce the injury. Also noticeable was the stress from oxadiazon (2G) treatments of 4 lb/A in April, 2 + 1 + 1 lb/A in April, May and July, 2 + 1 lb/A in April and May, and 3 + 1 lb/A in April and July. Butralin (2G with fertilizer) treatments producing noticeable stress on September 26, 1975 were 6 and 8 lb/A in April, 4 + 2 + 2 lb/A in April, May and July, 4 + 4 lb/A in April and May and 8 + 2 lb/A in April and July. By September 26, 1975 materials and rates providing statistically similar (5% level of probability) suppression of goosegrass with minimal injury to the Kentucky bluegrass and annual bluegrass turf were: benefin (2.5G) at 3 + 0.75 lb/A in April and July (13% goosegrass), oxadiazon (2G) at 2 and 3 lb/A in April (10% and 6% goosegrass respectively), oxadiazon (2G) at 2 + 2 lb/A in April and May (0% goosegrass), and 2 + 1 lb/A in April and July (0% goosegrass). Butralin (2.3G) at 8 lb/A in April (17% goosegrass), 4 + 2 + 2 lb/A in April, May and July (8% and 8% goosegrass respectively). Butralin (2.3G + fertilizer) at 4 + 2 lb/A in April and May (18% goosegrass) and 6 + 2 lb/A in April and July (12% goosegrass). Check plots contained 37% goosegrass on September 26, 1975. |
|---|
