This article will discuss the redberry mite in blackberries, as the time to begin operations for its control is rapidly approaching. 

 

Redberry mite is a serious pest of commercially produced blackberries in Santa Cruz and Monterey counties in California. Redberry mite activity prevents berries from ripening uniformly, causing from one to many druplets to remain as a bright red cluster on the otherwise black and fully ripe fruit. Affected druplets never do ripen, causing the entire fruit to be inedible and unmarketable. 

 

Varieties of blackberry, such as Ollalieberry, which bear fruit in the early part of the season, from late May to the beginning of July, tend to have less redberry mite damage and are less of a concern. However, later bearing varieties such as Chester, Triple Crown, Navaho and Apache do get redberry mite and an absence of control can lead to significant losses.

Horticultural oils, such as Golden Pest Spray Oil, when used at the rate of 1.2 to 2% volume oil to volume water carrier, should begin to be applied after the blackberry reaches green fruit or when you see the first pink fruit. Follow the first application with two to three more applications, spaced 2 or 3 weeks apart. These applications will give significant control of redberry mite, while causing less harm to fruit yield than the traditional lime-sulfur or sulfur sprays.

The minimum amount of water carrier for oil applications should be 50 gallons per acre.

The potential for phytotoxicity of oil product or oil product mixes has not been fully evaluated for all blackberry varieties in all growing areas. Small plot tests are prudent to determine safety margins of particular blackberry varieties for specific environmental conditions in different growing areas.

There are several insecticides mentioned for control of redberry mite in this article. Before using any insecticides, check with your local Agricultural Commissioner's Office and consult product labels for current status of product registration, restrictions, and use information.