Modeling the Effects of the Environment and the Host Plant on the Ripe Rot of Grapes, Caused by the Colletotrichum Species.

Tao Ji,Vittorio Rossi,Irene Salotti,Ming Li,Chaoyang Dong

doi:10.3390/plants10112288

Abstract

Ripe rot caused by Colletotrichum spp. is a serious threat in many vineyards, and its control relies mainly on the repeated use of fungicides. A mechanistic, dynamic model for the prediction of grape ripe rot epidemics was developed by using information and data from a systematic literature review. The model accounts for (i) the production and maturation of the primary inoculum; (ii) the infection caused by the primary inoculum; (iii) the production of a secondary inoculum; and (iv) the infection caused by the secondary inoculum. The model was validated in 19 epidemics (vineyard × year combinations) between 1980 and 2014 in China, Japan, and the USA. The observed disease incidence was correlated with the number of infection events predicted by the model and their severity (ρ = 0.878 and 0.533, respectively, n = 37, p ≤ 0.001). The model also accurately predicted the disease severity progress during the season, with a concordance correlation coefficient of 0.975 between the observed and predicted data. Overall, the model provided an accurate description of the grape ripe rot system, as well as reliable predictions of infection events and of disease progress during the season. The model increases our understanding of ripe rot epidemics in vineyards and will help guide disease control. By using the model, growers can schedule fungicides based on the risk of infection rather than on a seasonal spray calendar.

Highlights

Ripe rot of grapes is an important disease that can cause severe yield losses and deterioration of grape vines, and reduces grape and wine quality, including color and flavor
The relational diagram describes the main stages of the Colletotrichum spp. life cycle, including the following: (i) production and maturation of primary inoculum, (ii) infection caused by primary inoculum, (iii) production of secondary inoculum, and (iv) infection caused by secondary inoculum
The relative severity for primary infections is expressed as the proportion of the dose of the conidia produced by affected and mummified clusters that overwintered in the vineyard and that mature, disperse, and settle on flowers and berries, and infect and cause disease symptoms

Summary

Introduction

Ripe rot of grapes is an important disease that can cause severe yield losses and deterioration of grape vines, and reduces grape and wine quality, including color and flavor. The disease increases volatile acidity and the contents of residual sugar, glycerol, gluconic acid, and malic acid, resulting in a bitter off-flavor for the fruit and wine [1,2]. Ripe rot was first reported in the USA [3] and is currently present wherever host species (V. labrusca, V. vinifera, and V. rotundifolia [4]) are grown. Ripe rot can affect grapevine leaves and stems but is most important on clusters [4,6]. The typical disease symptoms usually appear on ripening berries after véraison and near harvest. May remain on the rachis or drop to the soil [4]

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