Disease management in organic rabbiteye blueberries

Abstract

Non-indigenous fruit crops such as peaches, apples, and vinifera grapes have limited potential for organic production in the southeastern United States due to the substantial pest pressures associated with the long growing season and the warm, humid climate. In contrast, rabbiteye blueberries, which comprise a large majority of the blueberry acreage in the Southeast, are native to the region and are well adapted to cope with its challenging climate, poor soils, and extensive pest complexes. Although rabbiteye blueberries are resistant to several important diseases affecting other blueberry species, all rabbiteye cultivars appear susceptible to mummy berry disease and most are affected by one or more foliar diseases such as Septoria leaf spot, Gloeosporium leaf spot, and/or leaf rust. This article briefly reviews old and new approaches for controlling these diseases organically. Mummy berry can be managed by pathogen exclusion, soil cultivation against overwintering primary inoculum, and application of a Bacillus subtilis-based biofungicide against secondary infection of flowers. For foliar diseases, host resistance is the first line of defense, whereas fish oil-based biofungicides have provided promising levels of disease suppression on susceptible cultivars. Knowledge gaps and future research needs are discussed. © 2008 by The Haworth Press. All rights reserved.