In vivo efficacy of fungicides for control of acid rot in grapes

RODRIGUEZ ROMERA, M.; PONSONE, M.L.; LONGONE, M.V.; COMBINA, M:

Mendoza

Congreso; 37th World Congress of Vine and Wine; 2014

OIV

The acid sour rot is caused by a yeasts complex (Saccharomyces cerevisiae, Pichia membranifaciens, Issatchenkia orientalis y Pichia galeiformes). This yeasts complex can trigger the disease in presence of micro-damages and along with acetic acid bacteria presents in the grapes can produce the acid sour rot symptomatology. The symptoms can appear since veraison, with visible cuticle oxidation, grape pomace softening and maceration, must loss, grape berries emptying, acetic acid production and Drosophila melanogaster presence. Until now there is a lack of knowledge in the disease control in Argentina. The aim of this work was to evaluate several chemical controls for acid sour tot pathogens in different doses: Cyprodinil 37,5 % + Fludioxinil 25% WG (80, 100 y 120 g/100L); Cupper Oxicloride 84% (400,450 y 500 g/100L); Metil azinfos 20% PV (300 y 400 g/100L); Cupper dioxide (2 y 3 L/ha); Aminothiazole(180, 230 y 500 cm3/100mL) y Pirimetanil 30 % SC (2,5 y 3 L/ha). The in vivo assay, under controlled lab conditions, was performed using Red Globe grapes variety. Humid chambers were performed with 30 grape berries each one x 6 repetitions/treatment. Micro damages were done in each grape berries with hypodermic needle. The berries of each treatment were sprinkled with each chemical product, after the product application the berries were aired for 2 hs. Later on, the yeast strains previously identified as causal agents of acid sour rot were applied to the grape berries (Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia membranifaciens and Pichia galeiformes) in a cocktail suspension of 8,2 x 106 cels/mL. The boxes of each treatment were hermetically sealed and incubated at 27°C for a 21 days period. The symptoms evaluation was done at 7, 14 and 21 days of incubation. After each evaluation the incidence of the disease was calculated (I = Nº grape berries with visible symptoms/total number of evaluated grape berries x 100). To evaluate the effect of each chemical product over acid sour rot visible symptoms, analysis of variance (ANOVA) was done using InfoStat for Windows Version 2013p. When the analysis was statistically significant; the Fisher (LSD) multiple-comparison test was used for separation of the means. Statistical significance was judged at the level p