Pest Information: The Annual Bluegrass Weevil
Distribution and Seasonality of the Annual Bluegrass Weevil
The annual bluegrass weevil (ABW) is the most troublesome insect pest for golf course superintendents in the northeastern United States. ABW is largely a specialist on highly maintained Poa annua, damaging playing surfaces such as fairways, tees, approaches, collars and even greens. Once limited to southern New England, impact from the insect has spread over the past four decades to areas as far north as the Canadian provinces of Ontario and Quebec, to as far west as eastern Ohio and south to the mountains of North Carolina. Identifying and suppressing overwintered adults is a key to controlling future generations of the pest.
Movement on Golf Courses
In the spring, starting as early as March, ABW adults move to susceptible golf course turf from adjacent overwintering sites such as litter along tree lines, in tall grass and other protected areas. From mid-April to May, overwintered females lay eggs in the stem or under the leaf sheaths of annual bluegrass. Then from late May through mid-June, larvae of this first generation cause extensive turf damage, first as stem borers and then as crown feeders.
In late June through early July, after pupation in the top layer of the soil, adults of the first generation emerge, feed, mate and lay eggs to start the cycle anew with a second and sometimes third generation. As the summer progresses, the life stages and generations become less synchronous, making it more difficult for golf course superintendents to interpret the life cycle and target the insect for control.
Early season control of the first generation of ABW is vital for avoiding the problem posed by multiple generations and overlapping life stages in summer and fall. As such, Syngenta presents its Optimum Control Strategy as a tool to mitigate ABW damage.
The Challenge of Controlling Annual Bluegrass Weevil
There are many reasons the annual bluegrass weevil is difficult to manage:
Early spring weather conditions determine when ABW adults become active.
Once active, ABW cycle through reproductive stages quickly, producing up to three or four generations in any given season.
Larvae from ABW reproduction develop at different rates.
Treatment products vary based on ABW lifecycle stages.
Detecting, monitoring and tracking ABW development requires multiple techniques supported by WeevilTrak.com.
Generational Control Depends on Early Detection and Proper Timing of Spring Applications
The key to successful ABW control is proper decision-making on the timing of early-season treatments. Missing an opportunity to control ABW early in the spring often means dealing with them all summer long.
The WeevilTrak database contains multiple years of degree day information that has been thoroughly reviewed and is used to refine when the treatments in the Syngenta ABW Optimum Control Strategy should be applied. For many years, superintendents have successfully used forsythia bloom stage as their primary phenological indicator for initiating a monitoring and control program for adults.
Conversely, degree day monitoring offers a marked improvement over phenological indicators because of the precise manner in which heat accumulation in the spring is recorded and translated into a decision making process. Degree day monitoring devices are strategically placed on WeevilTrak monitoring courses to identify the latest date that the various treatments of the Optimum Control Strategy should be applied. The first treatment is often recommended regardless of whether ABW adults have been observed, because of the irregular nature of this pest.