Yourman L F, Jeffers S N
Department of Plant Pathology and Physiology, Clemson University, Clemson SC 29634-0377.
Plant Dis. 1999 Jun;83(6):569-575. doi: 10.1094/PDIS.1999.83.6.569.
In 1996 and 1997, 325 isolates of Botrytis cinerea were collected from 35 commercial greenhouses growing ornamental crops in South Carolina to determine the incidence of resistance to benzimidazole and dicarboximide fungicides. Conidium germination was assessed on a defined agar medium amended with either thiophanate-methyl (a benzimidazole) or vinclozolin (a di-carboximide). A total of 53 representative isolates were evaluated further for conidium germination and mycelium growth on fungicide-amended medium and for infection of geranium seedlings treated with thiophanate-methyl or vinclozolin at label rates. Isolates were considered sensitive to thiophanate-methyl or vinclozolin when the effective concentration of the fungicide active ingredient resulting in 50% inhibition of germination (EC-germ) was ≤5 μg/ml or when the effective concentration of fungicide active ingredient resulting in 50% inhibition of mycelium growth (EC-growth) was ≤1 μg/ml. Of all isolates, 81% (262/325) were resistant to thiophanate-methyl and 69% (223/325) were resistant to vinclozolin. Four phenotypes were observed: sensitive to both fungicides (17%), resistant to both fungicides (67%), resistant only to thiophanate-methyl (14%), and resistant only to vinclozolin (2%). Isolates resistant to at least one fungicide were found in 33 of the 35 locations from which samples were taken. Disease incidences on geranium seedlings treated with 600 μg/ml of thiophanate-methyl and then inoculated with isolates sensitive and resistant to this fungicide were 1.4 and 96.1%, respectively. Disease incidences on geranium seedlings treated with 600 μg/ml of vinclozolin and then inoculated with isolates sensitive and resistant to this fungicide were 0.3 and 91.9%, respectively. With thiophanate-methyl, correlation coefficients (r) between disease incidence and log EC-germ or log EC-growth were 0.987 and 0.992, respectively. With vinclozolin, correlation coefficients between disease incidence and log EC-germ and log EC-growth were 0.975 and 0.893, respectively. Correlation coefficients between the two EC values for thiophanate-methyl were 0.989 and for vinclozolin were 0.900. Isolates sensitive to thiophanate-methyl had a mean EC-germ value of 0.93 μg/ml and a EC-growth value of 0.11 μg/ml. For isolates sensitive to vinclozolin the mean EC-germ value was 1.63 μg/ml and the mean EC-growth value was 0.26 μg/ml. Thiophanate-methyl-resistant isolates had mean EC-germ and EC-growth values greater than 500 μg/ml while vinclozolin-resistant isolates had a mean EC-germ value greater than 500 μg/ml and a mean EC-growth value of 3.18 μg/ml.
1996年和1997年，从南卡罗来纳州35个种植观赏作物的商业温室中采集了325株灰葡萄孢菌分离株，以确定对苯并咪唑和二甲酰亚胺类杀菌剂的抗性发生率。在添加了甲基硫菌灵（一种苯并咪唑）或乙烯菌核利（一种二甲酰亚胺）的特定琼脂培养基上评估分生孢子萌发情况。总共对53株代表性分离株进行了进一步评估，以检测其在添加杀菌剂的培养基上的分生孢子萌发和菌丝体生长情况，以及用甲基硫菌灵或乙烯菌核利按标签剂量处理天竺葵幼苗后的感染情况。当导致50%萌发抑制的杀菌剂活性成分有效浓度（EC-萌发）≤5μg/ml，或导致50%菌丝体生长抑制的杀菌剂活性成分有效浓度（EC-生长）≤1μg/ml时，分离株被认为对甲基硫菌灵或乙烯菌核利敏感。在所有分离株中，81%（262/325）对甲基硫菌灵耐药，69%（223/325）对乙烯菌核利耐药。观察到四种表型：对两种杀菌剂均敏感（17%）、对两种杀菌剂均耐药（67%）、仅对甲基硫菌灵耐药（14%）和仅对乙烯菌核利耐药（2%）。在采集样本的35个地点中的33个地点发现了对至少一种杀菌剂耐药的分离株。用600μg/ml甲基硫菌灵处理天竺葵幼苗，然后接种对该杀菌剂敏感和耐药的分离株，病害发生率分别为1.4%和96.1%。用600μg/ml乙烯菌核利处理天竺葵幼苗，然后接种对该杀菌剂敏感和耐药的分离株，病害发生率分别为0.3%和91.9%。对于甲基硫菌灵，病害发生率与log EC-萌发或log EC-生长之间的相关系数（r）分别为0.987和0.992。对于乙烯菌核利，病害发生率与log EC-萌发和log EC-生长之间的相关系数分别为0.975和0.893。甲基硫菌灵的两个EC值之间的相关系数为0.989，乙烯菌核利的为0.900。对甲基硫菌灵敏感的分离株的平均EC-萌发值为0.93μg/ml，EC-生长值为0.11μg/ml。对乙烯菌核利敏感的分离株的平均EC-萌发值为1.63μg/ml，平均EC-生长值为0.26μg/ml。对甲基硫菌灵耐药的分离株的平均EC-萌发和EC-生长值大于500μg/ml，而对乙烯菌核利耐药的分离株的平均EC-萌发值大于500μg/ml，平均EC-生长值为3.18μg/ml。
