Nitrogen fertility, mowing height and topdressing effects on anthracnose

By |  February 18, 2015 0 Comments
A measuring tape is placed along plots to measure ball roll distance on annual bluegrass putting green turf receiving different levels of nitrogen fertility, mowing height and sand topdressing.

A measuring tape is placed along plots to measure ball roll distance on annual bluegrass putting green turf receiving different levels of nitrogen fertility, mowing height and sand topdressing.

Anthracnose on annual bluegrass (Poa annua) greens, caused by Colletotrichum cereale Manns, can be suppressed by increasing nitrogen fertility, mowing height and sand topdressing. Effects of these practices on disease severity and ball roll remain unknown.

A three-year field trial was initiated in 2012 in North Brunswick, N.J., to evaluate the effects. Treatments were all combinations of mowing height (0.09 and 0.125 inch), N fertility (2.05 and 4.1 lbs. N/1,000 ft2/year) and sand topdressing (950 and 2000 lbs. sand/1000 ft2/year during 2012; 750 and 1650 lbs. sand/1000 ft2/ year during 2013 and 2014). Trinexapac-ethyl was applied weekly at 0.125 oz./1000 ft2, and lightweight vibratory rolling was performed three times/week.

As expected, increased N fertility, mowing height and sand topdressing reduced disease severity; reported as the area under the disease progress curve (AUDPC). N fertility accounted for the majority of the variation in AUDPC, and mowing height accounted for a slightly greater amount than sand topdressing. Interestingly, more frequent sand topdressing produced greater disease suppression when turf was maintained under low nitrogen and low mowing (compared to high) in 2012 and 2014.

Recovery from disease damage was enhanced by higher mowing, increased N fertility and more frequent topdressing. Recovery was substantially hindered by low mowing under infrequent topdressing. In regard to ball roll distance, the relative importance of management factors differed from that observed with AUDPC responses. Increased mowing height caused a substantial reduction in ball roll distance; greater N fertility and sand topdressing had minimal effects on ball roll distance. These findings suggest that priority should be given to lowering mowing height rather than reducing N fertility or sand topdressing rates to increase ball roll distance without greatly increasing the risk for anthracnose.

James Hempfling, graduate research assistant, Bruce Clarke, Ph.D., extension specialist in turfgrass pathology and James Murphy, Ph.D., extension specialist in turfgrass management, are at Rutgers University. For more information, contact Hempfling at james.hempfling@rutgers.edu.

Photo: Youssef Elkhateeb

This article is tagged with and posted in Research


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