Intercropping garlic plants reduces Tetranychus urticae in strawberry crop

Abstract

The effect of aromatic plants on number of twospotted spider mite (TSSM), Tetranychus urticae Koch, when intercropped with strawberry were assessed in the field. During the first year, chives (Allium schoenoprasum L.), coriander (Coriandrum sativum L.), fennel (Foeniculum vulgare Mill.), garlic (Allium sativum L.), oregano (Origanum vulgare L.), or sweet marjoram (Origanum majorana L.) were intercropped with strawberry. Assessments were performed on TSSM populations by taking six samples from July 20 to September 20, 2012. During the second year, garlic plants were intercropped between rows of strawberry at three densities in greenhouse and field. Mobile forms and eggs numbers (only in field) of TSSM were evaluated from April 18 to June 05 (greenhouse) and June 06 to August 14, 2013 (field). It was found that intercropping with garlic caused a greater reduction of TSSM (up to 52 %) in strawberry plants when higher populations of TSSM occurred in the field. TSSM reduction was found in one sample when fennel and chives were intercropped with strawberries (42 and 50 % reduction, respectively); this also occurred when populations of TSSM were higher. The three densities of garlic plants (one, two and three rows among the strawberry rows) reduced TSSM mobile forms by 49, 53 and 60 % (greenhouse) and 44, 51 and 65 % (field), and eggs by 38, 43 and 64 % (field), respectively. The results suggest that intercropping garlic plants between strawberry rows is a promising strategy to reduce TSSM populations.