Anthracnose Development on Annual Bluegrass Affected by Seedhead and Vegetative Growth Regulators

摘要

The impact of plant growth regulators on anthracnose (Colletotrichum cereale) severity in annual bluegrass (Poa annua) putting greens has been a concern for turf managers. Two field studies assessed the influence of mefluidide (ME; applied twice at 0or 0.69 fl oz/1000 ft~2) or ethephon (EP; applied twice at 0 or 5.0 fl oz/1000 ft~2) and three application intervals of trinexapac-ethyl (TE; 14 days, 7 days, or not applied) on anthracnose severity and seedhead production of annual bluegrass mowed to aheight of 0.125 inch from 2005 to 2007. Growth regulators did not enhance anthracnose, but occasionally and inconsistently reduced disease severity. Mefluidide had little effect on anthracnose, but ethephon reduced disease 3 to 22% compared to non-EP-treated turf. Trinexapac-ethyl applied every 7 or 14 days reduced anthracnose 4 to 29% and 4 to 16% compared to non-TE-treated turf, respectively. Ethephon reduced seedhead cover 12 to 47%, while ME suppressed seedhead cover 12 to 15%. Trinexapac-ethyl-treated turf retained seedheads for longer periods than non-TE-treated turf, especially when applied every 7 days. Few meaningful interactions occurred in anthracnose or seedhead cover between TE and ME or TE and EP. Thus, TE and EP, or ME can be used on annual bluegrass turf to reduce seedheads without intensifying anthracnose, and may occasionally reduce disease severity.