Cooperative Extension Contra Costa
UC Delivers Impact Story

Redberry mite management in blackberries

The Issue

Redberry mite management in blackberries
The partially ripe redberry mite fruit is a symptom of redberry mite.
The redberry mite is a small eriophyid mite affecting blackerries. Fruit infested with redberry mite are often rendered partially or completely unripe, and are inedible. Historically, redberry mite has negatively impacted blackberry production in Santa Cruz and Monterey counties, and has, at times, left 50 percent or more of the crop unmarketable.

Dormant season applications of the chemical lime sulfur has been used as the main management strategy against redberry mite, but provides only limited control of the pest. The need for a more effective and lower environmental risk alternative to lime sulfur for the control of redberry mite has been seen as essential to keeping blackberry production sustainable in the region.

What Has ANR Done?

In 2003, Santa Cruz County UC Cooperative Extension Farm Advisor Mark Bolda, in cooperation with industry partners, began trials to test various conventional miticides and horticultural oils as possible alternatives to lime sulfur as redberry mite control materials. Subsequent trials over three crop seasons evaluated the performance of various products and rates of application as well as timing to discern best control of the pest.

The Payoff

Environmentally friendly horticultural oils control redberry mite in blackberry

Several materials were identified as being effective for redberry mite management over time, however, the most efficacious were horticultural oils. This finding is especially important because horticultural oils have a lower environmental impact than lime sulfur, are relatively easy to use by growers, and, when applied three to four times after blackberry plants flower, control redberry mites well with little negative effect on fruitfulness.

Within two years of this discovery, it is estimated that at least 50 percent of blackberry acreage in Santa Cruz and Monterey counties use this new pest management strategy.

Contact

Mark Bolda, Strawberry and Caneberry Farm Advisor, UC Cooperative Extension, Santa Cruz County
Telephone(831)763-8040, mpbolda@ucdavis.edu