For those superintendents who have battled annual bluegrass weevil over the years, it is common knowledge that there is no one shot, silver bullet cure/control option. ABW is a complex insect with multiple generations of adults and with several larval instars within each generation. Thus, it makes complete sense that a multi-product, programmatic approach is a necessity, in an effort to maximize control and minimize damage throughout the year. Based on reviewing numerous research trials over the past ten years, a solid ABW solutions program would be similar to the following:
First Generation ABW
- Overwintering Adults – Generally found in early to mid-April, it would be important to apply a product such as UP-Star® SC (bifenthrin) or another synthetic pyrethroid to knock back the adult populations. Acephate® 97UP (or another organoposphate, such as chlorpyrifos) are also options, where pyrethroid resistance is prevalent.
- Early Instar Larvae – By late April to early May, it is common to find early instar larvae in the sheath/stem of the annual bluegrass plant.For control at this stage, it would be necessary to use a systemic insecticide, such as Avatar® PLX (acephate + imidacloprid), Acephate® 97UP, spinosad, or chlorantraniliprole.
- Late Instar Larvae – By mid-May to early June, late instar larvae have often exited the plant and usually can be found between the residual biomass and the upper root zone.Control options at this time would include products such as, Acephate® 97UP, Avatar® PLX, chlorpyrifos, spinosad, cyantraniliprole or indoxacarb.
Second Generation ABW
- Second Generation Adults – These adults are commonly found in mid to late June.At this time, control options would include products such as UP-Star® SC (or another SP) and Acephate® 97UP (or another OP).
- Second Generation Adults or Late Instar Larva – Found in late June or early July, control options would include Acephate® 97, spinosad, or indoxacarb.Additionally, for those looking for grub control, Avatar PLX (acephate + imidacloprid) could also be positioned at this point at a one-time 8 lb/A rate.
- Miscellaneous Larvae – At this point in the summer, depending on your program, you may or may not see any additional larval damage, but it is imperative that you continue to check on a regular basis.In the event larvae are present, your control options, to be positioned two to three weeks following your last application, would be products such as Acephate® 97UP, chlorpyrifos, spinosad, or cyantraniliprole.
Third Generation ABW
- It is possible to see a third generation of ABW adults and larvae, depending on the weather patterns through the year.In the event that adults and larvae are present in late August to early September, it would be recommended to make an application of Acephate® 97, spinosad, or indoxacarb to assist with the control.
The challenge of controlling an ABW outbreak throughout a typical golf season can be rather daunting. The common feedback from most superintendents has been that once you know you have an infestation, it is most important to stick with the control program from start to finish of the ABW season. Failure to do so usually results in unfavorable turf damage.
It is important to mention a few things. First, in areas where synthetic pyrethroid resistance is a primary concern, one of the alternative active ingredients mentioned should be used. Second, product labels should always be read and understood prior to any pesticide application. Finally, it is important to understand that some of these products and/or active ingredients may have seasonal application limits and it is important to follow these limits to the letter of the law to avoid any possible fines.