IPM strategy pushes away pests while pulling in beneficials

02/18/2013 04:51:00 PM
Renee Stern

As an introduced species, Western flower thrips flourish on cultivated crops but are forced to "duke it out" with their native cousins on weeds and other native plants. There, Florida flower thrips "can flood the environment," he says.

The native thrips outcompete Western flower thrips.

Encouraging Florida flower thrips means growers trade "the risk of a little bit of damage versus the bigger problems of Western flower thrips," Frantz says.

In the second year of Surround treatments, the predator-prey ratio hit the critical level for pest suppression and extinction a week earlier than in the control plots, Frantz says. One predator for every 180 thrips is considered enough for suppression, while increasing the numbers to one predator per 40 thrips achieves control.

The underlying is unclear, Tyler-Julian says.

Theories include an irritant effect, uncomfortable levels of light from the kaolin's reflective qualities, the pest's problems with gripping the plant and laying eggs through the additional material—or a combination of these.

Kaolin sprays may be a harder sell for pepper and tomato growers than other pieces of the push-pull strategy, Frantz says.

The whitish residue must be washed off fruit after harvest.

But because benefits appear within two weeks of use, growers may be able to reduce the amount and number of sprays over the season, simplifying cleanup, he says.

A trap-crop border

Meanwhile, planting alternate host plants on the edges of field rows reduced the number of thrips on pepper and tomato plants, Tyler-Julian says. Those tests found a correspondingly lower incidence of tomato spotted wilt virus.

Infected Western flower thrips transmit the virus while feeding on plants as adults. Laying eggs on infected plants passes the disease to a new generation that acquires it as larvae to spread tomato spotted wilt virus in its turn.

Keeping infected adults away from vulnerable crops stops that chain from continuing.

Parts of the state, including Palm Beach County, have low populations of minute pirate bugs.

"Farms are too clean," Funderburk says. "There's not enough wild vegetation" to attract beneficials or to serve as traps for Western flower thrips.

That's where companion plantings of sunflowers for peppers and Spanish needle for tomatoes come in. But more work is needed to determine best practices as well as any additional benefits, he says.

One of those benefits seems to be in aphid control, says Gene McAvoy, a University of Florida regional vegetable Extension specialist in LaBelle.

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