UC Davis researchers are reporting the largest successful use of integrated pest management in the commercial floriculture industry. They controlled two key pests on cut-rose plants by following a careful program of introducing predators, applying pesticides and revising culture (growing) conditions.

As a result, they reduced pesticide use, which is good for worker health and safety, the environment and the growers' bottom line.

Cut-rose production is the largest component of California's $300 million cut-flower industry. The most recent data available, from 2001, shows that the state's production represented 66 percent of the U.S. rose crop, with a wholesale value of $45 million.

The study -- conducted in collaboration with eight commercial growers in San Diego, Santa Barbara and Santa Cruz counties — showed that a predatory mite called Phytoseiulus persimilus could effectively and economically control twospotted spider mites (Tetranychus urticae).

To control western flower thrips (Frankliniella occidenalis), growers limited pesticide spraying to 70 gallons per acre in the upper canopy -- where thrips are most prevalent -- rather than applying the typical full-volume spray of 275 gallons per acre in conventional cut-rose greenhouses. The growers also implemented cultural controls, such as removing fully open flowers, where thrips lay their eggs.

The study appears in the April-June issue of UC's peer-reviewed journal California Agriculture: CaliforniaAgriculture.ucop.edu.

—California Agriculture and UC Davis News Service