Epidemiology, identification and disease management of grape black rot and potentially useful metabolites of black rot pathogens for industrial applications – a review

Abstract

Phyllosticta ampelicida (teleomorph: Guignardia bidwellii) is the fungal plant pathogen that causes black rot on grapevine. It is able to infect all green, expanding grape tissues. Black rot poses a threat to both yield and wine quality; a severe attack can virtually cause a complete crop loss. The fungus is native to North America, and was spread to Europe at the end of the 19th century. With the beginning of the 21st century, an increasing importance of the disease was observed in several European winegrowing regions. Successful black rot control strategies combine sanitary measures, cultural techniques, growing cultivars with reduced susceptibility and the use of effective fungicides. Berries are most susceptible to infections between flowering and bunch closure and consequently, fungicide applications against black rot need to focus on this period. In this paper, forecast models and decision support systems that help to achieve satisfactory control with a minimum of fungicide input are presented. Black rot in grapevine was reported to be well controlled in field experiments by a broad range of fungicide classes including quinone outside inhibitors (98 ± 3% efficacy), demethylation inhibitors (98 ± 3% efficacy) and dithiocarbamates (92 ± 7% efficacy). Average efficacies of other fungicide classes tested so far ranged from 32 to 69%; meta data on the efficacy of fungicides in numerous field trials are given. At present, black rot causes major problems primarily if vineyard management and fungicide use were reduced or abandoned. Organically managed vineyards are highly affected. Hence, site and cultivar selection as well as cultural measures are of the highest importance especially in organic viticulture. Recent studies showed that some strains formerly classified as G. bidwellii in fact belong to a distinct species (P. parthenocissi). Black rot pathogens produce some phytotoxic secondary metabolites, such as phenguignardic acid, guignardic acid, alaguignardic acid and the guignardianones A, E and F, which could stimulate the development of new herbicides of natural origin.

Composition and evaluation of a novel web-based decision support system for grape black rot control

“…Since studies of Loskill et al (2009) demonstrated that spores (conidia or ascospores) are produced throughout the growing season in the overwintering mummies, VitiMeteo Black rot assumes sufficient inoculum to be present throughout the season (in regions or vineyards with black rot symptoms in the previous or the present year). Since conidia are responsible for the rapid spread of the disease in the field (Ferrin and Ramsdell 1978), they are considered as major source of infections during summer (Molitor and Beyer 2014).…”

“…Black rot lesions on leaves reduce assimilation and form the inoculum for further infections during the season while most severe damage is caused by cluster infections. From an economic point of view, almost no black rot damage on the clusters can be tolerated (Molitor and Beyer 2014).…”

“…Severe epidemics cause yield losses of up to 100 % (Rinaldi et al 2013b) making black rot one of the economically most important fungal diseases of grapevine in the regions concerned. Successful black rot control strategies integrate sanitary measures, cultural techniques, the use of cultivars with lower susceptibility as well as direct chemical control measures (Hoffman et al 2004;Molitor and Beyer 2014). Black rot infections are possible by both, conidia and ascospores.…”

“…Black rot infections are possible by both, conidia and ascospores. Conidia liberated in vast quantities (Harms et al 2005) are responsible for the rapid spread of the disease in the field (Ferrin and Ramsdell 1978) and are hence considered as the major source of black rot infections during summer (Loskill et al 2009;Molitor and Beyer 2014). In general, black rot infections on leaves (Spotts 1977), grape berries (Molitor 2009) and shoots (Northover 2008) are possible if temperature dependent wetness durations are exceeded.…”

Phytotoxic dioxolanones are potential virulence factors in the infection process of Guignardia bidwellii

“…The secondary metabolites are believed to be involved in the pathogenicity of G. bidwellii and can be described as potential virulence factors, due to the fact that the application of the pure compounds onto the host tissue causes specific disease symptoms 6 . Additional studies should be conducted to corroborate this hypothesis.…”