May 13, 2002
Grub Control:
Preventative treatment vs. curative treatment

If you had beetles last year, you can bet you'll have grubs this year. If you're a landscape manager looking for early preventative control with minimal impact to the environment, humans and wildlife, your best option may be a new preventative grub treatment.

     According to Pam Charbonneau, OMAFRA turf­grass specialist at Guelph, Ontario, the only real advantage of curative chemicals is they allow turf managers to monitor an area and spray only once when the threshold has been surpassed. Curative treatment applications are timed for the grub's late first and early second instar stages, which occur in mid- to late August. "It's nearly impossible to go in any earlier, since you can't see the grubs themselves," Charbonneau explains. "Wait until after the first of September, and your turf will already have sustained damage."

     MERIT, designed for preventative control was recently introduced for use in Ontario. Charbonneau states that a preventative control product, such as MERIT is a good alternative to curative control measures as the product requires no evidence of damage before treatment and offers long-lasting residual benefits.

     This new, preventative treatment is applied from before egg laying through hatch, which generally occurs between June and August. The grubs are destroyed before they begin their feeding frenzy. "Efficacy with preventative treatment is good because the grubs are targeted when they are very small," she points out. "The only drawback is that you may end up treating areas that aren't infested. You will need to rely heavily on past history of areas of infestations." Leo Blydorp, Bayer technical specialist in Ontario, agrees that applying these products to areas historically prone to grub infestation is the best way to work preventative products into a conscientious pest management program. "If you noticed adult beetles in certain areas last year, your best bet is to spray the areas early," suggests Blydorp.

     Other potential infestation problems are assoc­iated with open, sunny areas with dry, sandy soils. Blydorp cautions that once eggs have hatched and signs of damage are visible, landscape managers are forced to take more drastic measures. "At this point, the grubs are large and harder to kill with insecticide," he explains. "Several spray applications of a curative chemical may be required to control the infestation." Blydorp adds that rates are higher for a single application of the currently recommended curative products than they are with a preventative treatment product.

     Another point for the preventative treatment regime is that typically these products, MERIT included, have a longer residual effect, Charbonneau notes. This is a new addition to the turf manager's control mechanisms, and it also means timing of the application is less critical for busy turf managers. "A residual benefit does exist with a properly timed curative," she admits, "but curatives all have a short residual, so it is very important to time your application accurately."

     Characteristics of curative and preventative control methods are supported by ongoing research on control of white grubs and European chafer on turf, according to Fred Vaughn, president of Vaughn Agricultural Research Services. Vaughn's Cambridge- based, independent pesticide testing company has worked in the Food Systems 2002, Pest Management Research Program, a joint research effort undertaken by OMAFRA, whose goal is to reduce pesticide use by 50 per cent in the next three years.

     Vaughn is a fan of preventative control. "I'd favour a preventative for effectiveness. A preventative treatment can reduce the amount of damage the turf could sustain. Curatives are fine - they work well enough, but you risk damage from both grubs and predators alike. Skunks and raccoons will tear up the turf in search of their prey, leaving an unsightly mess - a real nightmare for managers of an aesthetic crop like turf.

     "Preventative products may cost a little more, but I'd pay the premium in a heartbeat. They are so much better," he says.

     Take the time to analyze the life cycles and make an appropriate treatment choice for your turf. The new preventative grub treatment option now available may fit into your business.