Sensitivity and Cross-Resistance of Botrytis cinerea (Cause of Strawberry Grey Mould) to Three New Fungicides in Hunan Province, China

Abstract

This study aimed to clarify the sensitivity and cross-resistance of Botrytis cinerea on strawberries to fluazinam (FAN), boscalid (BCI) and phenazine-1-carboxylic acid (PCA) to guide the rational use of these drugs. By measuring the mycelial growth rate, the sensitivity of 126 strains of B. cinerea on strawberries to FAN, BCI and PCA in 9 regions of Hunan Province was determined. The results showed that highest half maximal effective concentration (EC50) values for FAN, BCI and PCA against B. cinerea on strawberries were 0.9840 µg/mL, 9.0564 µg/mL and 11.2239 µg/mL, respectively; the minimum values were 0.0135 µg/mL, 0.1347 µg/mL and 1.3540 µg/mL, respectively, while the mean values were 0.1349 ± 0.1710 µg/mL, 2.1238 ± 1.9095 µg/mL and 5.2601 ± 2.2908 µg/mL, respectively. The highest values were 70.22-, 73.15- and 8.29-times higher, respectively, than the minimum values. The sensitivity frequencies of the three fungicides against B. cinerea on strawberries were not normally distributed, suggesting that sub-populations with reduced sensitivity were present in the B. cinerea population. Cross resistance to FAN, BCI and PCA existed. Field experiment results showed that the best control of B. cinerea occurred with FAN at 84.87%, which was 1.28-times that of the control, followed by BCI. PCA had the lowest control effect, which was lower than that of the control drug. This study provides a basis for decision-making in the future development of new policies for the prevention and control of B. cinerea.