Be Aware & Vigilant

08/01/2010 02:00:00 AM
Renee Stern

“New growth (eventually) becomes old growth,” says Jim Price, entomologist at the University of Florida’s Wimauma research center.

Over time, the damage hinders plant growth and production.

Identify pest, then treat

In strawberries that damage—a black streaking on leaves—is obvious at a glance, Price says.

In other plants damage may show up either as undersized leaves or leaves that are crinkled with brown streaks, Ludwig says.

But other thrips as well as broad mites produce similar effects, Seal says. Growers always should pinpoint which problem pests are in their fields in order to devise the most effective control program.

Chilli thrips are whitish, with a small band on their abdomen, and are smaller than either melon or western flower thrips, he says.

So far, Price has found chilli thrips only in isolated spots on commercial farms, mainly on strawberry field margins, where the pest has migrated in from nearby landscaping plants—unlike western flower thrips, which typically blow in and cover fields more uniformly.

“Be aware of your vulnerability to the problem,” he says. “If you’re near residences with landscape plants, scout accordingly.”

Consider treatments’ effects on other insects, too

Shrub roses, a popular landscaping plant with a growing season that runs from spring to fall, are a particular concern, Ludwig says.

Neighboring nurseries can pose similar threats, Seal says. And consider quarantining transplants to be sure they’re pest-free before setting them out in fields.

After scouting fields, growers should follow recommended spray plans and rotate pesticide classes to manage resistance.

And, Osborne says, keep the big picture in mind. Going overboard on sprays against chilli thrips may lead to a more dangerous problem with western flower thrips, which vector tomato spotted wilt virus and other diseases.

“We don’t want to create a resistance problem in western flower thrips,” he says.

“Growers can make their own problems,” Frantz says. “There are some pesticide use patterns that can trigger [pest] population increases.”

Frequent pyrethroid sprays are a prime example, he says. Pyrethroids wreak havoc on thrips’ predators and other beneficial insects. The end result can be a population explosion in western flower thrips.

In addition to neonicotinoids as a foliar spray, the researchers suggest other traditional thrips’ controls, including abamectin (marketed as Agri-Mek, among other brands) and spinosads, such as Radiant.

Biological controls also play a role. Osborne cites one study that’s demonstrated the benefits of predatory mites to manage the pest.



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