Control of the fungi Lasiodiplodia theobromae, the causal agent of dieback, in cv. syrah grapevines

Carine Rusin,Renato Vasconcelos Botelho,Fabio Rossi Cavalcanti,Marcus André Kurtz Almança,Cacilda Márcia Duarte Rios Faria,Patrícia Carla Giloni De Lima

doi:10.4025/actasciagron.v43i1.44785

Abstract

Grapevine trunk diseases are among the most important limiting factors of worldwide viticulture. In this context, we aimed to verify the effect of chemical fungicides, biological agents and plant extracts on the control of Lasiodiplodia theobromae in pruning wounds and their physiological effects in cv. Syrah grapevines. Plant extracts (clove, cinnamon, garlic, rosemary and lemongrass), commercial fungicides (difeconazole, tebuconazole, mancozeb, sulfur, pyraclostrobin, fosetyl-Al, and azoxystrobin), chitosan, Trichoderma harzianum and Bacillus subtilis were used for the in vitro trials. The protection of pruning wounds in the potted vines was studied using fosetyl-Al, tebuconazole, Trichoderma harzianum, Bacillus subtilis, garlic extract and clove extract. The experiments were carried out through two vegetative cycles: 2015/2016 and 2016/2017. The length of wood discoloration, pathogen re-isolation percentage, fresh mass of the pruning material, peroxidase activity, fluorescence, chlorophyll index, phenological stages, shoot length and leaf area were evaluated. The treatments with clove, garlic extract, tebuconazole, pyraclostrobin, mancozeb, fosetyl-Al and B. subtilis reduced mycelial growth by more than 90%. In the grapevines, the use of T. harzianum decreased the re-isolation of L. theobromae, but no differences were verified for the other plant evaluations. We concluded that the use of T. harzianum would be a potential option for wound protection without altering the physiological aspects of cv. Syrah grapevines.

Highlights

Grapevine trunk diseases (GTDs) are among the most important limiting factors of viticulture in the world
The genus Lasiodiplodia is the causal agent of grapevine dieback, which is referred to as black dead arm or Botryosphaeria canker
In Brazil, Lasiodiplodia theobromae (Pat.) Griff. & Maubl (Correia et al, 2013) and Lasiodiplodia brasiliense (Correia et al, 2015) were isolated from grapevine decline symptomatic plants. These pathogens usually infect plants via pruning wounds and grafting points (Úrbez-Torres & Gubler, 2009); they can be passed from the grapevine mother plants to the young through grafting or other processes of propagation at nurseries (Gramaje & Armengol, 2011)

Summary

Introduction

Grapevine trunk diseases (GTDs) are among the most important limiting factors of viticulture in the world. Several trunk fungi may be responsible for these diseases, affecting both Vitis vinifera L. and Vitis labrusca cultivars Among these fungi, the genus Lasiodiplodia is the causal agent of grapevine dieback, which is referred to as black dead arm or Botryosphaeria canker. & Maubl (Correia et al, 2013) and Lasiodiplodia brasiliense (Correia et al, 2015) were isolated from grapevine decline symptomatic plants. These pathogens usually infect plants via pruning wounds and grafting points (Úrbez-Torres & Gubler, 2009); they can be passed from the grapevine mother plants to the young through grafting or other processes of propagation at nurseries (Gramaje & Armengol, 2011). The infection is favoured by conditions that reduce plant vigour, such as frost, high temperatures in the summer months, poor nutrition and poorly conducted pruning, and is associated with several disease symptoms, including foliar chlorosis, stunted growth, the dieback of shoots, spurs and side-branches, canker of the trunk or side-branches, wedge-shape cankers in the vascular tissue and mortality (Larignon & Dubos, 2001)

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