U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS), San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648.
Plant Dis. 2020 Mar;104(3):787-792. doi: 10.1094/PDIS-04-19-0844-RE. Epub 2020 Jan 15.
Gray mold caused by is an emerging postharvest disease of mandarin fruit in California. Management of postharvest diseases of mandarins relies on postharvest fungicides; however, multiple resistance to fungicides of different modes of action is common in populations from mandarin, leading to their failure to control decay. Natamycin is commonly used in the food industry as an additive, and it has been registered as a biofungicide for postharvest use on citrus and some other fruits. Sensitivity to natamycin of 64 isolates of from decayed mandarin fruit with known resistance phenotypes to other citrus postharvest fungicides (azoxystrobin, fludioxonil, pyrimethanil, and thiabendazole) was tested. Effective concentrations of natamycin to cause a 50% reduction relative to the control for conidial germination were from 0.324 to 0.567 µg/ml (mean of 0.444 µg/ml), and those for mycelial growth were 1.021 to 2.007 µg/ml (mean of 1.578 µg/ml). Minimum inhibitory concentrations where no fungal growth was present were 0.7 to 1.0 µg/ml for conidial germination and 5.0 to 10.0 µg/ml for mycelial growth. No cross-resistance between natamycin and other citrus postharvest fungicides was detected. Decay control efficacy tests with natamycin were conducted on mandarin fruit inoculated with isolates exhibiting five different fungicide resistance phenotypes, and natamycin significantly reduced incidence and lesion size of gray mold on fruit, regardless of fungicide resistance phenotypes. Natamycin has the potential to be an effective tool for integration into postharvest fungicide programs to control gray mold and manage isolates resistant to fungicides with other modes of action.
由 引起的灰霉病是加利福尼亚州柑橘类水果采后出现的一种新兴病害。柑橘类水果采后病害的防治依赖于采后杀菌剂；然而，来自柑橘的 种群对不同作用模式的杀菌剂普遍存在多抗性，导致它们无法控制腐烂。纳他霉素通常在食品工业中用作添加剂，并且已被注册为用于柑橘和其他一些水果采后的生物杀菌剂。对 64 株来自腐烂的柑橘果实的 分离株的纳他霉素敏感性进行了测试，这些分离株对其他柑橘采后杀菌剂（肟菌酯、氟唑菌酰胺、嘧菌酯和噻菌灵）具有已知的抗药性表型。相对于对照，导致孢子萌发减少 50%的纳他霉素有效浓度为 0.324 至 0.567 µg/ml（平均值为 0.444 µg/ml），对菌丝生长的有效浓度为 1.021 至 2.007 µg/ml（平均值为 1.578 µg/ml）。没有真菌生长的最小抑制浓度为孢子萌发的 0.7 至 1.0 µg/ml，菌丝生长的 5.0 至 10.0 µg/ml。未检测到纳他霉素与其他柑橘采后杀菌剂之间的交叉抗性。用纳他霉素对表现出五种不同杀菌剂抗性表型的 分离株接种的柑橘果实进行了腐烂控制功效测试，无论杀菌剂抗性表型如何，纳他霉素都显著降低了果实灰霉病的发病率和病斑大小。纳他霉素有可能成为一种有效的工具，可整合到采后杀菌剂方案中，以控制灰霉病并管理对其他作用模式的杀菌剂具有抗性的 分离株。
