Treating for the annual bluegrass weevil with the Optimum Control Program
2011 DuPont Optimum Control Program—For Control of ABW Plus Grubs and Caterpillars
A total program approach is being recommended for annual bluegrass weevil (ABW) control.
Given the recent documentation of pyrethroid resistance by certain ABW populations—primarily in Connecticut—this program incorporates a range of insecticides with different modes of action.
Each insecticide will be utilized to target the most vulnerable life stage for that particular product. The program anticipates the worst-case scenario of a prolonged period of egg laying by overwintered ABW adults and also recognizes that, under some circumstances, even high levels of control of first generation larvae will not completely prevent damage by summer generations of ABW.
First Generation Control
Three products featuring three different modes of action will be incorporated in the program designed to prevent damage from first generation larvae in May and June.
FIRST APPLICATION: The first application will call for an adulticide — usually a pyrethroid, but chlorpyrifos is also an option. This application will be based on degree days; however, be sure to carefully monitor for adults and check the WeevilTrak Web site for proper timing in your area.
The adulticide application accomplishes three important tasks:
1. Based on the contact activity of these active ingredients, it reduces overall ABW pressure by killing overwintered adults as they walk from overwintering sites onto areas of highly managed annual bluegrass.
2. It prevents early egg laying by gravid overwintered female ABW.
3. In keeping with the concept of trying to provide insecticide protection over a roughly two-month period, it allows Acelepryn® to be applied slightly later in the season as was recommended in 2010.
SECOND APPLICATION: DuPont™ Acelepryn® insecticide is a remarkably forgiving product when applied for white grub or caterpillar control. For white grubs, excellent control will be achieved from applications made anytime between early April and late July. For caterpillars, a single application of 8 fluid ounces per acre will provide season-long control of cutworms, armyworms and sod webworms.
Although Acelepryn® is highly active against ABW larvae (see Table 1), timing is critical because effective control is thought to depend on the systemic uptake of Acelepryn® by the annual bluegrass plant.
This suggests that it is important to have Acelepryn® moving in the transpiration stream of the annual bluegrass plant when the young (and extremely vulnerable) ABW larvae hatch and begin to chew their way into the stem. Empirical evidence suggests that Acelepryn® will provide high levels of control of ABW larvae that hatch about three weeks after application.
The timing of this application will be made roughly two to three weeks after the first application and will be based on degree day monitoring (check the WeevilTrak Web site for proper timing in your area).
Acelepryn® applied at 12 fluid ounces per acre accomplishes three important tasks:
1. It provides about three weeks of ABW larval control.
2. It provides season-long white grub control.
3. It provides season-long cutworm control.
THIRD APPLICATION: The third component of the program targeting first generation ABW larvae is an application of DuPont™ Provaunt® insecticide during late May or June to control late hatching larvae.
This application is critical because June is often when the first period of really hot weather occurs in the northeast, which makes annual bluegrass exceptionally vulnerable to damage.
University turfgrass researchers and private consultants from throughout the region will be monitoring ABW larval development, and this information will be available here on the WeevilTrak Web site.
Provaunt® applied at 12 ounces per acre will:
1. Target the early third instar larvae as they emerge from the annual bluegrass stem and move to feed on the crown of the plant.
2. Provide two to three weeks of residual control, which will complete the control program for first generation ABW larvae.
Control of Summer Generations
First generation ABW populations may reach more than 300 larvae per square foot of turfgrass. Under such high population pressure, even programs that provide exceptionally high levels of control will allow a certain number of individuals to survive and produce subsequent generations throughout the summer.
Early in the summer, there is still some predictability of the dominant ABW life stages present in turfgrass.
First generation adults generally appear in late June and early July, making them obvious targets for another adulticide application featuring a pyrethroid or 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 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.
Notes