Evaluation of different control strategies for the management of redberry disease associated with Acalitus orthomera (Eriophyoidea: Eriophyidae) in commercial blackberry crops

Abstract

In Mexico, redberry disease in blackberry (Rubus sp.) was first observed in Tacambaro, Michoacan, in 2011, causing losses greater than 70%. In this study, the eriophyid mite species associated with buds and berries and its association with redberry disease were identified. Based on morphology, the specimens of mites collected from the buds and fruits were identified as Acalitus orthomera (Keifer in Bull Dept Agric State Calif XL(3):93–104, 1951) (Acari: Eriophyidae). The eriophyid mite densities in the buds of fruiting laterals were moderately to highly positively correlated (ρ = 0.6–0.95) with redberry disease incidence at harvest. In the second part of this study, the effects of different management strategies on the density of A. orthomera in fruiting lateral buds and redberry disease incidence were evaluated. Two IPM and organic experimental plots were established during the 2014 and 2016 seasons. Treatments were based on sequential or alternating applications of lime sulfur, plant extracts, soybean oil, the entomopathogenic fungus Hirsutella thompsonii, and acequinocyl, abamectin, and hexythiazox. Treatments were applied either from budbreak or the start of the blooming period. Management programs based on the application of lime sulfur alone or in blocks or alternating with acequinocyl, abamectin, or neem extracts were effective in reducing A. orthomera densities in buds and the incidence of redberry disease when applied either after budbreak or at the beginning of the blooming period; some of these treatment schemes are feasible for use in organic systems. These results will contribute to optimizing the management of redberry disease in blackberry in the context of integrated pest management.