John C. Inguagiato, James A. Murphy, and Bruce B. Clarke. Rutgers University, Dept. of Plant Biology & Pathology, 59 Dudley Rd. Rutgers Univ., New Brunswick, NJ 08901
Sand topdressing has been associated with a potential increase in anthracnose disease on putting green turf. The effect of sand topdressing rate (0, 0.3 and 0.6 L m-2) and frequency (7-, 14- and 28-d) on anthracnose severity was evaluated in North Brunswick, NJ using a randomized complete block design during 2006 and 2007. Treatments were applied in a factorial arrangement to annual bluegrass turf maintained at a 3.2-mm mowing height. The topdressing rate of 0.3 L m-2 increased anthracnose on 12 July 2006 compared to no topdressing; however, less disease was observed in topdressed plots compared to non-topdressed plots from 7 to 16 August 2006. Topdressing rate was inversely related to disease from 28 August to 6 September 2006. Sand applied at 0.6 L m-2 reduced disease compared to non-topdressed plots from 25 July to 2 August 2007. Topdressing frequency did not affect disease until 7 August through 9 September 2006, when anthracnose was reduced in plots topdressed every 7-d compared to 14- and 28-d intervals. By early August 2007, frequency had not affected disease. Topdressing rate interacted with frequency in August and September 2006 indicating a cumulative benefit of sand topdressing. In early August, 0.6 and 0.3 L m-2 sand every 7-d had less anthracnose than no sand, while only the 0.6 L m-2 level at the 14-d frequency had less disease than no sand. By September, anthracnose was less severe in plots receiving 0.6 L m-2 of sand at all frequencies and 0.3 L m-2 of sand at the 7- and 14-d intervals but not the 28-d frequency. A topdressing rate and frequency interaction was becoming evident (p = 0.093) by early August 2007. Contrary to the common perception, these data indicate that sand topdressing does not generally increase anthracnose and can enhance recovery from this disease.
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