Screening of Botrytis cinerea isolates from vineyards in Israel for resistance to fungicides

Abstract

Plots in two vineyards in the Golan Heights, Israel were treated with six botryticides during three growing seasons with 3 applications per season. Applications of fenhexamid, pyrimethanil and cyprodinil + fludioxonil were effective, resulting in 52-65% and 53-63% mean reduction in grey mould incidence and severity, respectively. Carbendazim, fluazinam and iprodione were ineffective or slightly effective. Five hundred and sixteen B. cinerea isolates were collected from infected berries or trapped from the air in the vineyards, and profiles of sensitivity to benomyl, fenhexamid, fluazinam, fludioxonil, iprodione and pyrimethanil were established for each of the isolates based on a mycelial growth test. Seventyfour percent of the isolates were sensitive to the six tested fungicides, and the other 26% of the isolates were classified into 10 phenotypes characterized by resistance to one or more fungicides. Resistant isolates showed fitness parameters similar or reduced in comparison to sensitive isolates. Resistance to benzimidazoles and to dicarboximides was the most frequent (up to 25%) and apparently pre-existed in the populations tested. Increased frequency of benzimidazole resistance, but not dicarboximide resistance, was observed following the 3 years of applications of the fungicides. High level resistance to pyrimethanil was present at a frequency of about 2% in both vineyards in the first 2 years of the sampling survey and reached 10% in the third year at Site 2. A few isolates were resistant to fenhexamid or fludioxonil (0.8 or 0.2%, respectively). No strong resistance to fluazinam was detected, although numerous, less sensitive isolates, presumably possessing multi-drug resistance traits, were recovered at higher frequency from the plots treated with fluazinam than from the untreated plots.

Occurrence of fungicide resistance in populations of Botryotinia fuckeliana (Botrytis cinerea) on table grape and strawberry in southern Italy

“…As for the hydroxyanilide fenhexamid, classified by FRAC as a fungicide at low to medium resistance risk (http://www.frac.info), until 3–4 years ago, B. fuckeliana resistant isolates were rarely detected in southern Italy. Fenhexamid resistance was reported in northern Italy, Israel, Croatia, France, Germany, the United States and Chile . A dramatic increase in resistance frequency was recorded during the present monitoring in vineyards exclusively sprayed in 2–3 consecutive seasons with fenhexamid (up to eight sprays) exceeding the maximum number of sprays (2–3) recommended by FRAC and even established by the product labels.…”

Genetic structure and fungicide sensitivity of Botrytis cinerea populations isolated from grapevine in northern Italy

“…Populations of B. cinerea resistant to cyprodinil have already been reported on table grape and strawberry in southern Italy (De Miccolis Angelini et al ., ), in French and German vineyards (Leroux et al ., ; Leroch et al ., ), and in Greek vegetable fields (Myresiotis et al ., ). In contrast, resistance to the phenylpyrrole fludioxonil was found, always combined with anilinopyrimidine resistance, at low frequencies in grapevine isolates in southern Italy (De Miccolis Angelini et al ., ), Israel (Korolev et al ., ) and southwest Germany (Leroch et al ., ). Because fludioxonil alone has never been used in the investigated vineyards, the high rates of fludioxonil resistance found in A could be explained by the use of the active substance on apple orchards right before harvest to prevent postharvest infections.…”

Molecular characterisation and detection of resistance to succinate dehydrogenase inhibitor fungicides in Botryotinia fuckeliana (Botrytis cinerea)

“…The intensive usage of fungicides with single‐site mode of action and the great adaptability of B. fuckeliana underlie the frequent occurrence of fungicide resistance in field populations of the pathogen. Fungicide resistance in B. fuckeliana has been frequently reported all over the world, including Italy …”