Mefluidide Applications for Annual Bluegrass Seedhead Suppression Based on Degree‐Day Accumulation¹

Abstract

Mefluidide [N‐(2,4‐dimethyl‐5‐{[(trifluoromethyl)sulfonyl] amino}phenyl) acetamide] is an effective growth regulator for annual bluegrass [Poa annua var. reptans (Hauskins) Timm.] seedhead suppression. The effectiveness of mefluidide is dependent on the rate and timing of application. The objective of this field study was to determine the lowest effective rate and the proper time for mefluidide application based on growing degree‐days (GDD). Soil types were a fine, mixed, mesic Aeric Ochraqualf and fine‐loamy, mixed, mesic Typic Glossoboric Hapludalfs for Columbus, OH, and East Lansing, MI, respectively. The rates evaluated were 0.140, 0.070, and 0.035 kg ha−1 of mefluidide. The applications were made at 15, 25, 30, and 45 GDD. Degree‐days were accumulated using a sine curve as an approximation of the diurnal temperature curve. The base temperature used was 13°C. Mefluidide applied between 15 and 30 GDD at 0.140 kg ha−1 gave excellent seedhead suppression. Mefluidide applied between 15 and 30 GDD at 0.070 kg ha−1 gave moderate seedhead suppression. Applications of mefluidide at 45 GDD or at the 0.035 kg ha−1 rate were unacceptable.

Anthracnose Severity on Annual Bluegrass Influenced by Nitrogen Fertilization, Growth Regulators, and Verticutting

“…Ong and Marshall (1975) found that assimilate redistribution to ABG roots increased when developing seedheads were physically removed compared to where seedheads were allowed to mature. Mefluidide limits seedhead production of ABG (Danneberger et al, 1987) and it provided the greatest control of seedheads in our study. Several studies have shown that application of ME re‐allocates photosynthate away from shoots and seedheads to root and crown tissues (Cooper et al, 1987, 1988; Hanson and Branham, 1987).…”

Early and Late Postemergence Control of Dallisgrass in Tall Fescue

“…GDD models have been shown to accurately predict the growth of various cereals and grasses (6,10,16,20,23,25,26,28,38). Additionally, GDD models have been used to maximize the efficacy of insecticide (36) and plant growth regulator (7,13) applications to managed turfgrass systems.…”

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

“…In the current study, ME probably did not sufficiently inhibit seedhead production (only 12 to 15% reduction) to adequately divert photosynthate from the developing inflorescence (27) to improve root growth and reduce disease. Timing of ME application can influence seedhead suppression (9). Danneberger et al (9) evaluated annual bluegrass seedhead suppression with ME applications based on growing degree days.…”

“…Timing of ME application can influence seedhead suppression (9). Danneberger et al (9) evaluated annual bluegrass seedhead suppression with ME applications based on growing degree days. They observed that ME applications at 25 and 30 accumulated growing degree days (base 32°F beginning 1 April) provided the greatest seedhead suppression; whereas ME applied at 15 and 45 degree days was less effective.…”