Effects of Trichoderma asperellum and Trichoderma gamsii and hot water treatment on Phaeomoniella chlamydospora in grapevine plant propagation material.

Phaeomoniella chlamydospora, associated with Petri disease and Esca in young and mature plants, respepectively affects plant propagation material frequently as latent infections. Curative methods are few and scarcely effective and hence proactive prevention measures are indispensable to limit the presence of the pathogen especially in young vineyards. In this study, the biofungicide RemedierTM (ISAGRO S.p.A, Milan, Italy) composed by Trichoderma asperellum icc012 and T. gamsii icc080 and hotwater treatment (HWT) were applied individually and in combination for controlling P. chlamydospora during the propagation process in nursery and at planting in pots. Cuttings of 1103 Paulsen (P) rootstock or grafted plants cv. Italia/1103P were used in experiments carried out in the nursery (trials 1 and 2), and grafted plants Italia/1103P in the pot experiment (trial 3). The biofungicide was applied by soaking cuttings during the hydration stage, at planting and 15, 30 and 60 days afterwards. Propagation material artificially inoculated with a conidal suspension (106 spores ml-1) of P. chlamydospora strain CIA43.2, marked with benomyl resistance, was used after the first BCAs application. In trial 3, HWT plants were also compared. In all trials, the appropriate untreated and non-inoculated controls were also used. At uprooting, quality status of each plant was assessed at three different points and the presence of P. chlamydospora was evaluated by isolation on appropriate media. BCA-treated vines showed a significant (p≤0.05) increase in stems and roots development even as compared to untreated ones subjected to HWT. Phaeomoniella chlamydospora and Botryosphaeriaceae sp., the fungi isolated with prevalence higher than 10%, were significantly reduced (up to 100%) by HWT. BCAs reduced P. chlamydospora CIA43.2 up to 70%. These results contribute to an integrate management of esca and Petri disease in grapevine.