The annual bluegrass weevil (ABW) is one of the most troublesome insects for golf course superintendents in the northeastern and mid-Atlantic U.S. And according to GCM Magazine, the pest is spreading to new regions in southern parts of Quebec and Ontario in Canada, western North Carolina, and eastern Ohio. At the same time, more populations of the ABW are becoming resistant to currently available insecticides.

 

Annual bluegrass weevils are small, black beetles that cause significant damage to turf when the larvae hatch from eggs in the spring. Initially, larvae feed from within the turfgrass stem. Once older larvae become too large to fit within the stem of the plant, they exit the plant to feed on the crown, causing severe damage. ABW larvae cause turf to die, resulting in small yellow or brown spots. Since the damage is to the crown, recovery is often very slow. As the infestation spreads and becomes more severe, the small spots can enlarge and affect larger swaths of turf.

 

Up until recently, the common consensus for treating ABV involved early-season insecticide treatments to suppress overwintered adults and to control the first and second generations of ABW early in the season to avoid multiple generations and overlapping life stages in the summer and fall. However, recent findings published in GCM Magazine recommends not applying adulticides until populations have reached peak densities, as males are unlikely to be mature and few females are inseminated before this period. The findings go on to say that because most ABW adults do not feed between emergence from overwintering sites and arrival on short-mown golf course surfaces in the spring, systemic insecticide applications are unlikely to be effective against adults. Instead, the recommendation states that turfgrass manager may benefit from using onsite weather stations or growing-degree-day data loggers to predict population peaks.

 

These findings suggest an entirely different treatment method than traditionally thought. It also means that turfgrass managers who prefer to control adult ABV with short-term residual insecticides can wait until the peak adult emergence from overwintering sites. However, the challenge with peak emergence is it can vary greatly depending upon a golf course’s geographic location and springtime temperature fluctuations. Relying upon visual identification also is not ideal and may result in the need for a second treatment application.

 

Onsite weather stations, such as those available through Spectrum Technologies, can help predict population peaks of the annual bluegrass weevil by measuring weather conditions, such as humidity, temperature, and rainfall. Turf managers also can set up alerts via phone, text, or email immediately when temperatures cross the selected threshold, essentially removing the guesswork from identifying peak emergence periods.

 

Learn more Spectrum’s weather stations and view the different models available.