Resistance of Corynespora cassiicola of Hebei Province to three common fungicides and the control efficacy of alternative fungicides on cucumber target leaf spot
-
ZHU Guangxue,
-
YUE Yuanyuan,
-
ZHU Qingyan,
-
WEN Zhihao,
-
SUN Bingxue,
-
ZHOU Rongjia,
-
XIE Xuewen,
-
CHAI Ali,
-
LI Lei,
-
FAN Tengfei,
-
LI Baoju,
-
SHI Yanxia
-
Graphical Abstract
-
Abstract
In order to clarify resistance of Corynespora cassiicola to commonly used fungicides such as boscalid, trifloxystrobin and procymidoneoxime and screen effective fungicides, the sensitivity of C. cassiicola in Tangshan and Handan area of Hebei Province from 2020 to 2021 was detected by mycelium growth rate method, CcSdh and CcCytb resistant mutant genotypes were analyzed by PCR technique, the control efficacy of 10 commonly used fungicides against the local main resistant mutant SdhB-I280V&Cytb-G143A was evaluated by pot experiment, and the efficacy of the alternate use of highly effective alternative fungicides was carried out. According to the test results, the C. cassiicola in the main producing areas of cucumber in Tangshan and Handan of Hebei Province developed different degrees of resistance to boscalid, trifloxystrobin and procymidoneoxime. The average EC50 value of boscalid against the 280 strains of C. cassiicola was 8.12 μg/mL, with the resistance frequency was 27.43%. The average EC50 value of trifloxystrobin against the 144 strains of C. cassiicola was 62.6 μg/mL, with the resistance frequency against the 162 strains (including the 18 strains with EC50 value greater than 200 μg/mL) was 99.49%. The average EC50 of procymidoneoxime against the 163 strains of C. cassiicola was 6.95 μg/mL, with the resistance frequency was 52.76%. Eleven kinds of CcSdh resistance mutant types were detected in total, and the mutation frequency reached 56.86%. Six of them were single mutations, four of them were double mutations, and one of them was triple mutation. CcCytb carried only G143A mutation, and the frequency was 100%. In the pot experiment, the two mixed fungicides 75% chlorothalonil WP + 50% procymidone WP and 50% iprodione WP + 75% (pyraclostrobin + propineb) WP had the highest control efficacy on cucumber target leaf spot, with the control efficacy of 71.52% and 70.52%, respectively. The second was the compound fungicide 75% (pyraclostrobin + propineb) WP, and the control efficacy was 57.90%. 75% chlorothalonil WP + 50% procymidone WP and 50% iprodione WP + 75% (pyraclostrobin + propineb) WP were used alternately to control cucumber target leaf spot with 71.53% effect and 94.64% efficacy in pot experiment and field experiment, respectively. This showed that the mixing and alternate use of fungicides with different action mechanisms have broad application prospects for the control of cucumber target leaf spot.
-
-