Pyrethroid resistance in the Connecticut region

Pyrethroid resistance by annual bluegrass weevils was first documented in Connecticut during 2005.

This finding should not have been surprising considering that pyrethroids had been the primary insecticides used for ABW control since the mid- to late 1990s and that as many as six or more applications per year were made on many courses.

Subsequent studies by researchers from the University of Rhode Island and the Connecticut Agricultural Experiment Station confirmed high levels of pyrethroid resistance on numerous golf courses in Connecticut and, to a limited extent, other states.

This research also showed that enhanced metabolism by several enzyme systems was a major contributing factor to pyrethroid resistance by ABW. Metabolic resistance is particularly troublesome because there is potential that the resistance may be conferred to other classes of insecticide that feature different modes of action.

In general, adult insects have greater metabolic capacity than immature stages. And within the immature stages (larvae or nymphs) metabolic capacity increases with age.

So in order to maintain as many products as possible in an ABW management program, it is important to increase the use of ABW larvicides and to use them targeting the earliest possible larval instar.

The fact that insect enzyme systems metabolize insecticides from numerous insecticide classes could provide an opportunity for synergism using tank-mixtures of appropriate pesticides.

Research conducted against pyrethroid-resistant ABW populations by leading turf entomologists during 2009 showed surprising levels of ABW control when Acelepryn® was tank-mixed with bifenthrin. This suggests that there may be synergism when two active ingredients with demonstrated efficacy against ABW are used in conjunction to control resistant populations.

First Generation Control—Fairways

FIRST APPLICATION: The first application will utilize a tank-mixture* of DuPont™ Acelepryn® insecticide at 12 fluid ounces per acre combined with a labeled rate of a pyrethroid product. The timing of this application will be based on degree day monitoring (check this Web site for proper timing in your area).

SECOND APPLICATION: The second application will be made roughly two to three weeks after the first application and will consist of a labeled rate of a pyrethroid product. The timing of this application will be based on degree day monitoring (check this Web site for proper timing in your area).

THIRD APPLICATION: The third component of the program targeting first generation ABW larvae is an application of DuPont™ Provaunt® insecticide at 12 ounces per care during late May or June to control late hatching larvae (check this Web site for proper timing in your area).

First Generation Control—Greens, Tees and Surrounds

FIRST APPLICATION: The first application will utilize a tank-mixture* of Acelepryn® at 12 fluid ounces per acre combined with a labeled rate of a pyrethroid product. The timing of this application will be based on degree day monitoring (check this Web site for proper timing in your area).

SECOND APPLICATION: The second application will be made roughly two to three weeks after the first application and will consist of a tank-mixture* of Acelepryn® at 12 fluid ounces per acre combined with a labeled rate of a pyrethroid product. The timing of this application will be based on degree day monitoring (check this Web site for proper timing in your area).

THIRD APPLICATION: The third component of the program targeting first generation ABW larvae is an application of DuPont™ Provaunt® insecticide at 12 ounces per acre during late May or June to control late hatching larvae (check this Web site for proper timing in your area).

Control of Summer Generations—Greens, Tees, Surrounds and Fairways

First-generation adults generally appear in late June and early July, making them obvious targets for another adulticide application featuring one or two applications of a chlorpyrifos product.

By the middle of July, ABW populations have usually become asynchronous—meaning that all life stages are present at the same time and there often is not a single dominant stage. Late July through early August is prime time for a final ABW insecticide application.

Provaunt® should be considered the product of choice for this application because, in addition to excellent activity toward ABW larvae, Provaunt® provides surprisingly good control of ABW adults. An application of Provaunt® at 12 ounces per acre in this time period should carry most courses through to the end of the year.