Does Psa affect kiwifruit susceptibility to leafrollers?

Abstract

Analysis of kiwifruit industry pest monitoring and spray diary data showed increases in the incidence of leafroller larvae on fruit during crop monitoring in the 2011/12 season in regions with the virulent strain of the disease Pseudomonas syringae pv. actinidiae (Psa-V). Four factors were considered as explanations: Psa-V infection and its effects on plant defences, leafroller sprays, Psa-V sprays and leafroller sampling. The most plausible cause of the increased leafroller incidence is Psa-V infection. A putative mechanism is hormonal 'cross-talk' resulting in a trade-off between pest and pathogen resistance. The susceptibility of vines to leafrollers in Psa-V-infected regions appears to persist for several weeks longer after fruit set than in uninfected vines. The paper discusses the need to develop a better understanding of the interactions of biotic and abiotic stressors on plant defence responses to pests and diseases and to incorporate these into a plant-defence-centred approach to Integrated Pest Management. © 2013 New Zealand Plant Protection Society.