Wenzhou Botrytis Cinerea Disaster Law And Control Technology Research

Due to acutely epidemic outbreak of Botrytis cinerea on tomato in Wenzhou , an investigation on infection, epidemic and control of the disease was carried out since 2001.It was found that invasion of the pathogen on tomato fruits was most popular through petal residue (81%), and also through chapiter. The results obtained by couple-test method showed that the pathogen spread from the infection center. The first bundle of fruit was the key point for pathogen infection and for its control based on space distribution investigation. It is concluded that low-temperature and rainfall in spring,, high humidity, mass source of infection, unfavorable cultivation and cultivar modification were the main factors for severe outbreak of the disease.The result from test under protective cultivation indicated that the average adjusted efficacy of 30 % pyrimethanil FU on controlling Botrytis cinerea was 85.68% and 89.57% on tomato leaves and fruit, respectively. According to the figure of range R, the order of factors on control efficacy was application times > application amount > application intervals.As fungicide resistance of the pathogen is growing we attempted screening new ones such as diethofencarb for practical control. Indoor efficacies of 6.5% diethofencarb on Botrytis cinerea with dosages of, 2.0g/m² and 1.5g/m², were significantly higher than reference fungicide. The same results were obtained in field experiment with dosage of 1.0kg/667m²。Also, the six most popular fungicides were tested for their toxicity in vitro and control efficacy in field. Inhibision rate of the pathogen mycelial growth by each drug increased with higher concentration. The inhibition rate of 40% Pyrimethanil WP at 200mg·kg^-1 was 92.72%. That was 90.85% and 82.35% for 20% Procymidone SC at 200mg·kg^-1 and 50% Thiram WP at 200mg·kg^-1, respectively. EC₅₀ for 40% Pyrimethanil WP, 20% Procymidone SC. 50% Thiram WP, 50% Iprodione WP, 70%...