Monday, November 13, 2006
70-22
Effect of Chemical Growth Regulation Strategies on Anthracnose Severity of Annual Bluegrass Putting Green Turf.
John C. Inguagiato, James A. Murphy, and Bruce B. Clarke. Rutgers University, Dept. of Plant Biology & Pathology, 59 Dudley Rd., New Brunswick, NJ 08901
Chemical growth regulation on golf putting greens has become commonplace in recent years. Turf managers are currently using these materials at increased rates and decreased intervals; and the effect on anthracnose, caused by Colletotrichum cereale, is unknown. Nineteen treatments were arranged in a randomized complete block design with four replications. Trinexapac-ethyl (TE) was applied at various rates (0.3-, 0.4-, and 0.6-L ha-1) and intervals (7-, 14-d) April to September 2005 and 2006. Mefluidide (2.2-L ha-1) or ethephon (15.9-L ha-1) was applied 6 and 20 April 2005 or 31 March and 12 April 2006 both without and with trinexapac-ethyl (0.4-L ha-1) applied at two intervals (7- or 14-d) throughout the season. Anthracnose incidence declined linearly with increased TE rate in 2006, but not in 2005. Anthracnose damage was reduced 18-30% on 3 and 21 July 2006 by TE applied every 7-d compared to 14-d (mean of two rates). Interval of TE did not significantly affect disease in 2005. Mefluidide (ME), without and with TE, reduced disease 51% on 2 July 2005, and 14-39% in 2006. However, ME alone had 38-67% and 19-61% greater disease than the combinations of ME+TE in 2005 and 2006, respectively. No difference was observed between TE and ME+TE in either year. Ethephon (ET), with and without TE, had 30-51% and 24-78% less disease than untreated turf in 2005 and 2006, respectively. Ethephon alone was not different from combinations of ET+TE over both years. Trinexapac-ethyl was 45% less effective than ET+TE at reducing anthracnose on 15 July 2005, and 52% less effective on 3 July 2006. Ethephon, without and with TE, had 15-73% less disease in 2006 than ME without and with TE. There was no difference between ET and ME in 2005.