Consideration of Latent Infections Improves the Prediction of Botrytis Bunch Rot Severity in Vineyards.

Giorgia Fedele,Ana M Díez-Navajas,Laurent Delière,Vittorio Rossi,Elisa González-Domínguez

doi:10.1094/pdis-11-19-2309-re

Abstract

The current study validated a mechanistic model for Botrytis cinerea on grapevine with data from 23 independent Botrytis bunch rot (BBR) epidemics (combinations of vineyards × year) that occurred between 1997 and 2018 in Italy, France, and Spain. The model was operated for each vineyard by using weather data and vine growth stages to anticipate, at any day of the vine-growing season, the disease severity (DS) at harvest (severe, DS ≥ 15%; intermediate, 5 < DS < 15%; and mild, DS ≤ 5%). To determine the ability of the model to account for latent infections, postharvest incubation assays were also conducted using mature berries without symptoms or signs of BBR. The model correctly classified the severity of 15 of 23 epidemics (65% of epidemics) when the classification was based on field assessments of BBR severity; when the model was operated to include BBR severity after incubation assays, its ability to correctly predict BBR severity increased from 65% to >87%. This result showed that the model correctly accounts for latent infections, which is important because latent infections can substantially increase DS. The model was sensitive and specific, with the false-positive and false-negative proportion of model predictions equal to 0.24 and 0, respectively. Therefore, the model may be considered a reliable tool for decision-making for BBR control in vineyards.

Highlights

To determine the ability of the model to account for latent infections, postharvest incubation assays were conducted using mature berries without symptoms or signs of Botrytis bunch rot (BBR)
The model correctly classified the severity of 15 of 23 epidemics (65% of epidemics) when the classification was based on field assessments of BBR severity; when the model was operated to include BBR severity after incubation assays, its ability to correctly predict BBR severity increased from 65%
BBR severity observed in the field at maturity ranged from disease severity (DS) =

Summary

Materials and Methods

The model was operated using the vineyard’s weather data and vine GS to predict, on any day of the vinegrowing season, the epidemic group (severe, intermediate, or mild) at harvest (González-Domınguez et al 2015). Observed BBR epidemics were classified into three groups based on DS at harvest in the field and after incubation assays as follows: severe, DS $ 15%; intermediate, 5 # DS < 15%; and mild, DS < 5% (Table 2). Prior probabilities were calculated as the proportion of intermediate or severe epidemics P(O+) or mild epidemics P(O−) relative to the total number of epidemics observed in the field

Results

Discussion

Literature Cited