| Clubroot is a soil-borne disease prevailing worldwide for years, and makes great loss in production every year. The P. brassicae infects the plants and form tumors to seriously affect the development and growth of plants and withered to whole dead in later phase, so clubroot is a sever threat to cruciferous vegetables production. Present in Hubei Province, clubroot prevails on local sustainable production of cruciferous vegetables, estimated a total infection area of150,000Mu around and have a strong impact on local sustainable production of cruciferous vegetables. The anti-stress capacity of clubroot dormant spores is so strong that they can survive in soil for a relatively period; as a result, the application amount of pesticides for prevention is great in production. However, the affecting factors are too many to get stable and effective chemical pesticides for clubroot prevention. To select effective pesticides with more pertinence, allied toxicity measurement of clubroot dormant spores are taken, which facilitate further filed testing. And the main research results are as follows:1. The survive rate of clubroot dormant spores with direct pesticides treatment are calculated, and the survival rates of clubroot dormant spores by different pesticides’ treatment for different times are valued. And threshold with significant differences of survival time is made sure, which regards as an evidence for further test. According to this, it is proved that500g/L fluazinam suspending pesticides has good bacteriostastic activity. Effective screening applied on the prevention effects of different pesticides.2. To select effective pestcide against clubroot by pot experiment, perfusion method and mixing method are done. The prevention effects of10pesticides against Plasmodiophora brassicae are compared by stir and mix method and drench method. The results show that stir and mix method of500g/L fluazinam suspending pesticides can have a prevention effect with more than80%, dominantly better than treatments of other pesticides. Clubroot dormant spores with direct pesticides treatment were compared to an effective pesticides for culbroot prevention, the pharmaceutical group differences were not significant. 3. Effective duration of four selected pesticides with good prevention effects:500g/L fluazinam suspending pesticides,75%mancozeb wettable powder,72%urea cream?manganese-zinca are calculated.75%mancozeb wettable powder,72%urea cream?manganese-zinca intend to decline in20to40days in prevention effects and reaches below50%in60days, so these two pesticides’ residual life is20-40day. Duofu pesticides reached50%was also effective.500g/L fluazinam suspending pesticides’ effective duration is more than60days so it can meet the demand of growth period of Chinese cabbage.4.4selected pesticides from pot experiments are implemented in filed test. The results show that500g/L fluazinam suspending pesticides show80%distinction between pot and field experiments in prevention effect of Plasmodiophora brassicae, while75%mancozeb wettable powder,72%urea cream?manganese-zinca are both below50%. Also the average fresh weights (g), average production per Mu (kg) of Chinese cabbage after pesticides root drench treatment are shown in tables. For average fresh weights, there is no distinct difference among four pesticides’treatments and500g/L fluazinam suspending pesticides and Duofu wettable powder are better than the other two. For average production per Mu,500g/L fluazinam suspending pesticides is the best and Duofu wettable powder ranking the second. It is also found that there exists negative relation between disease rate and average production per Mu by perfusion method, and the disease rate of culbroot will dominantly affect the average production per Mu of Chinese cabbage.The research select prevention pesticides against cruciferous vegetables clubroot through indoor test, pot test and field test and make a valuable reference for clubroot prevention. |
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