Effect of management spontaneous cover crop on rosy apple aphid, green apple aphid and their natural enemies in an apple organic orchard

Abstract

Cover crops have been reported as shelters for pest but also for natural enemies. Nevertheless, there is not agreement about their influence on pest presence on apple trees. An experiment was conducted in 2004-2006 in an IRTA-Estació Experimental de Lleida organic apple orchard located in Les Borges Blanques (Lleida, Spain) in order to evaluate the influence of cover crops on the presence of pest and natural enemies on apple trees. Three cover crops were tested and compared to a bare soil: (1) spontaneous cover crop where Plantago lanceolata L. was the most abundant specie, (2) no-mowed spontaneous cover crop, (3) spontaneous cover crop mowed when weeds were 30 cm tall. Cover crops tested affected neither the presence the rosy apple aphid nor aphid natural enemies. Nevertheless, the green apple aphid was more abundant in bare soil trees than in cover crop trees