The Occurrence Regularity And Control Techniques Of Pear Scab In Guanzhong Fruit Zone

1.Though continues survey for 4 years on major pear-producing areas of Shaanxi province, which includes 50 counties belonged to 5 cities, we have a clear understanding on pear scab for the disease distribution and incidence. In summary, the disease focuses on 10 counties of Shaanxi province.2. Field trial showed that ascospores released at the end of May and the beginning of June from the fallen pear leaves of last year, the latent period of this pathogen is 14-20 days, pear scab occurred at the end of May. Peritheciums on the fallen leaves of last year are the mainly primary infection resource in Yangling.3. The results showed that pathogen growth and spore produce are different at different temperatures, this pathogen preferred to lower temperature, and spores produced more at pH4.0-pH6.0 than pH6.5-pH7.5, while light has little effect on vegetative growth, but significant effect on spore producing, on special light test the highest spore producing could reach more than 50 spores per average vision (10*10), the mycelium grows fast on PDA, and on LP'media can produce more spores.4 The experimental results through 17 measuring fungicides in the laboratory and in the field indicate that the lowest EC50 is 70% Antracol WP, the next are 12.5% Diniconazole WP and 50% carbendazim+mancozeb WP. We preliminary determined these three fungicides are the best agents for controlling the pear scab. Though the controlling effect of Celastrus angulatus extract (EC50-1.528μg/g) is lower than other fungicides, while it is safe to human and animals, especially easy to degrade and lower residual at natural environment, we may get the similar effect as other chemicals if we improve the concentration of this bio-assay...