Frequency of fungicide-resistant Botrytis cinerea populations isolated from ‘Thompson Seedless’ table grapes in the Central Valley of Chile

Abstract

were sensitive to all fungicides tested; from north to south, the frequency of sensitive isolates in the regions of Valparaiso, Metropolitana and O'Higgins ranged from 48.15% to 21.1% and 5.88%, respectively. Four hundred and twenty isolates (79%) showed resistance to single or multiple fungicides, 134 (25.4%) were simultaneously resistant to azoxystrobin and pyrimethanil. No fludioxonil-resistant isolates were found, indicating that fludioxonil has great potential for gray mold control in table grapes in Chile. From sixty randomly selected B. cinerea isolates, only the azoxystrobin-resistant isolates carried the G143A point mutation; according to the cytochrome b (cyt b) gene structure, the third intron Bcbi-143/144 was only detected in the azoxystrobin-sensitive isolates. The H272R and H272Y point mutations in the succinate dehydrogenase subunit B (sdhB) gene were associated only with the boscalid-resistant isolates. The F412S and F412V point mutations were found in the sequenced erg27 gene of randomly selected fenhexamid-resistant isolates. These results contribute to the knowledge of B. cinerea fungicide resistance for table grape vine crops in Central Chile, particularly for the development of multiple-resistance and the associated resistance mechanisms of azoxystrobin, boscalid and fenhexamid-resistant isolate populations. Antiresistance strategies are discussed in a general manner.

Characterization of fungicide sensitivity profiles of Botrytis cinerea populations sampled in Lombardy (Northern Italy) and implications for resistance management

“…The limitation in the number of fungicide sprays per season can, in fact, slow down the selection of resistant strains . The percentage of strains resistant to boscalid (2‐6%) is in line with that reported in other studies and lower than that reported for German vineyards, where the frequency of boscalid‐resistant strains reached up to 70% . Resistance to SDHI is of relatively recent discovery, and could probably be related to the increased use of the class .…”

“…Therefore, particular attention should be taken in monitoring its evolution in the field. Resistance to APs has been frequently reported in grapevine fields, where the percentage of resistant isolates can be lower than 10%, as found in the present study, or reach values ranging from 30 to 80% . Resistance to APs was detected early in the 2000s and is particularly widespread, however it proved to be unstable in absence of selection pressure: this could help to explain the wide variability in the diffusion of resistant strains found in the literature.…”

“…Resistance to APs was detected early in the 2000s and is particularly widespread, however it proved to be unstable in absence of selection pressure: this could help to explain the wide variability in the diffusion of resistant strains found in the literature. Resistance to PPs and KRIs in vineyards has been less frequently reported in the literature than resistance to members of the first two classes. While almost full sensitivity to the KRI member fenhexamid was found in the present study, the relatively high frequency of strains resistant to fludioxonil (5% on average) highlights the need to further investigate the phenomenon and analyze the disease management strategies adopted in vineyards to decrease the selection pressure of the class towards insensitive strains, that at present seems to be one of the main issues in the region.…”

“…Resistance to members of the individual classes or simultaneous resistance to different classes (multidrug resistance, MDR) has been reported in Botrytis cinerea (Pers.) strains isolated in vineyards located in France, Germany, Italy, United States, Chile, Australia and New Zealand . Fungicide resistance in B. cinerea is associated with point mutations at the gene encoding for the fungicide target and the overexpression of drug efflux transporters (ABC transporters) .…”

Endophytic Fungi Isolated from Plants Growing in Central Andean Precordillera of Chile with Antifungal Activity against Botrytis cinerea

“…Currently, the management of the disease is affected by the selection of B. cinerea isolates resistant to fungicides [ 3 ]. In a study realized in table grapes of Thompson Seedless variety in the Central Valley of Chile, it was demonstrated that only 1% of the B. cinerea isolates was sensitive to all of fungicide families [ 4 ]. Therefore, new alternatives for the control of this disease are necessary.…”