Water-mediated dissemination and chemical control of clubroot disease of cruciferous crops | 水介导十字花科作物根肿病的传播及其化学防治

chinois. 以感病的大白菜品种为供试材料，采用漂浮育苗池水和人工接种不同菌量的芸薹根肿病菌（Plas—modiophora brassicae Woronin）休眠孢子悬浮液，分析病菌在水和土壤环境中的致病性差异，观察病菌在不同含水量土壤中的传播距离、侵染程度和带菌水浇灌处理后的病情，并在水培育苗池中进行药剂筛选。结果表明：人工接种漂浮育苗有利于根肿病传播，且发病程度与接种的孢子悬浮液带菌量呈正相关，当以103、104、105、106、107个／g的菌量接种时，漂浮育苗植株的发病率分别为9．51％、19．88％、44．31％、63．65％、76．00％，传统旱育苗植株的发病率分别为5．33％、15．00％、20．67％、43．33％、45．00％；在土壤含水量为38％～1115％的基质上种植大白菜苗，接种根肿病菌后均能发病，其中以土壤含水量为77％时植株的发病率最高，当植株距离病菌5cm时，植株发病率达20．43％，距离病菌10cm时，植株发病率达10．23％；在水培育苗池中分别施人375．0mg／L的百菌清WP、250．0mg／L的多菌灵WP、25．0mg／L的氰霜唑SC、125．0mg／L的氟啶胺SC和262．5mg／L的BAS651FSC，其防治效果分别达96．65％、94．19％、87．93％、80．18％和88．02％，但所用剂量的氟啶胺SC和BAS651FSC对大白菜苗有药害作用。

anglais. By planting a susceptible Chinese vegetable in the seedling bed irrigated with Plasmodio- phora brassicae Woronin contaminated water from floatation culturing system （FCS） and inoculated with the resting spores of the pathogen, the pathogenicity was analyzed in water and soil, the spread distance of the pathogen and clubroot disease severity in the soil with different water contents and irriga- ted with different resting spores water was investigated, and chemicals were screened in the FCS for the disease control. The results showed that FCS inoculated with the pathogen favored the disease spread, and disease severity was positively related to the inoculum number. Disease incidences were 9. 51%, 19.88%, 44.31%, 63.65% and 76.00% in FCS and 5.33%, 15.00%, 20. 67%, 43.33% and 45.00% in traditional soil culturing system when 103 , 104 , 105 , 106 , 107 spores/g were inoculated onto Chinese cabbage respectively. Chinese cabbage became diseased when it was seeded in the culture substrate with 38 %-115 % water content, but the culture substrata with 77 % water content best benefited the disease. When the plants growing in the substrate were 5 cm and 10 cm far from the pathogen, the disease inci- dence were 20. 43% and 10. 23% respectively. The active ingredient of 375.0 mg/L chlorothalonil WP, 250. 0 mg/L carbendazim WP, 25.0 mg/L cyazofamid SC, 125.0 mg/L fluazinam SC and 262. 5 mg/L BAS651F were applied to the FCS, they could control 96. 65%, 94. 19%, 87. 93%, 80. 18% and 88.02% of the disease, respectively, but fluazinam SC and BAS651F inhibited the plant growth when their concentrations were used in this experiment.