Archivio Journal of Plant Pathology

Abstract:

Phytoplasmoses are severe diseases of grapevine and other crops, for which no effective means of control are available. However, plants infected by phytoplasma can undergo spontaneous symptom remission (recovery), a long-known phenomenon. A strategy to reduce the number of symptomatic plants could thus arise from the stimulation of plant defence systems to induce recovery. The aim of the present study was to evaluate the effectiveness of field treatments with resistance inducers to promote recovery in Bois noir (BN) infected grapevines. Five commercial products (Chito Plant, Aliette, Kendal, Bion, and Olivis) described as plant defence promoters were sprayed on the canopy of BN-infected grapevines of cv. Chardonnay. Treatments consisted of weekly sprays in spring-summer 2007 (seven applications) and 2008 (thirteen applications). All treatments increased the number of recovered plants with respect to the control. The best results were obtained with Kendal, Olivis and Bion, while Aliette and Chito Plant performed better in the first than in the second year. Molecular analysis of leaf vein extracts from recovered plants failed to detect the phytoplasma. An induction of host defence is likely to be responsible for the effectiveness of these resistance promoters in the control of BN.