Avaliação de parâmetros epidemiológicos da podridão por lasiodiplodia em uva nas cultivares itália muscat e thompsom seedless

Abstract

Lasiodiplodia Theobromae is responsible for numerous diseases in many economically important crops that may be infected in both pre and postharvest, may cause different symptoms. In grapevine, the pathogen infects the berries, causing Lasiodiplodia rot, causing injuries that impair or prevent the marketing of the fruit. Given the importance of this pathogen and the high levels of infection in the Lower Basin producing area of Submédio do Vale São Francisco, a region important in the production of fine table grapes, this study aimed to evaluate the epidemiological parameters of Lasiodiplodia rot in berries of grape cvs. Italy Muscat and Thompson Seedless. We conducted pathogenicity and aggressiveness of 10 isolates of L. theobromae (L1, L2, L3, L4, L5, L7 L6, L8, L9 and L10), inoculated on wounds produced by a punch with eight needles 2 mm deep on cv. Italy Muscat at a concentration of 106 spores/mL. All isolates tested were pathogenic to grape. In the test of aggression L1 isolate was more aggressive, with higher average compared to other injuries, which is used in subsequent tests. We studied the influence of region inoculation inoculum (equatorial and stalk), methods of inoculation (spray and drop) in addition to epidemiological parameters: concentration of inoculum (103, 104, 105, 106 and 107 spores/ml), a period of wetting (0, 12, 24, 36, 48h) and temperature (2, 5, 10, 15, 20, 25 ° C). Regarding to the inoculum concentration, for both cvs. Italy Muscat and Thompson Seedless, 107 conidia/ml was the best, using 10 μl applied on the equatorial region by droplet inoculation method promoting the highest development of lesions on grape berries. Concerning to the epidemiological parameters, temperature and wetness, there has been a further development of lesions in about 25 ° C under a 48 h wetting period.