Glynn Neil C, Hare Martin C, Edwards Simon G
Harper Adams University College, Newport, Shropshire TF10 8NB, UK.
Pest Manag Sci. 2008 Aug;64(8):793-9. doi: 10.1002/ps.1558.
Seed-borne Microdochium majus (Wollenweber) and M. nivale Fries are the primary pathogens responsible for Fusarium seedling blight in the UK. The two species show differences in pathogenicity, host preference and sensitivities to temperature, but their relative sensitivities to fungicide seed treatments are unknown. The aim was firstly to determine the efficacy of fungicide seed treatments towards single-spore isolates of M. majus and M. nivale using in vitro experiments, and subsequently to determine efficacy in vivo over a range of temperatures.
Differences in EC(50) values between all seed treatments were evident from the in vitro experiments and ranged from 0.028 mg L(-1) for fludioxonil to 22.8 mg L(-1) for carboxin + thiram. The two seed treatments that showed best performance in vitro were used to examine efficacy towards seed-borne infection in vivo at 4, 8, 12 and 16 degrees C. Generally, seedling emergence improved and the severity of stem-base disease symptoms on emerged seedlings was reduced for both species through the use of the fungicides. The combination of fludioxonil + difenconazole showed improved performance compared with fludioxonil alone. Significantly less severe symptoms were observed through the use of fludioxonil and fludioxonil + difenconazole compared with bitertanol + fuberidazole at 12 degrees C and for all except one M. nivale infected seed lot at 8 degrees C.
Differences in fungicide sensitivity between the two species in vitro were not evident in vivo. This is the first report of the effect of fungicide seed treatments on the control of seedling blight caused by M. majus and M. nivale.
种子传播的大微座孢（Wollenweber）和雪腐微座孢（Fries）是英国镰刀菌幼苗猝倒病的主要病原菌。这两个物种在致病性、寄主偏好和对温度的敏感性方面存在差异，但它们对杀菌剂种子处理的相对敏感性尚不清楚。目的首先是通过体外实验确定杀菌剂种子处理对大微座孢和雪腐微座孢单孢分离株的效果，随后确定在一系列温度下的体内效果。
体外实验表明，所有种子处理之间的EC(50)值存在明显差异，范围从咯菌腈的0.028 mg L(-1)到萎锈灵+福美双的22.8 mg L(-1)。在体外表现最佳的两种种子处理被用于检测在4、8、12和16摄氏度下对种子传播感染的体内效果。一般来说，通过使用杀菌剂，两个物种的幼苗出土率提高，出土幼苗茎基部病害症状的严重程度降低。咯菌腈+苯醚甲环唑组合的表现优于单独使用咯菌腈。在12摄氏度时，与联苯三唑醇+呋菌唑相比，使用咯菌腈和咯菌腈+苯醚甲环唑观察到的症状明显较轻；在8摄氏度时，除一个感染雪腐微座孢的种子批次外，所有种子批次使用这两种药剂时症状也明显较轻。
两个物种在体外对杀菌剂的敏感性差异在体内并不明显。这是关于杀菌剂种子处理对大微座孢和雪腐微座孢引起的幼苗猝倒病防治效果的首次报道。
