Research On The Control Effects Of Several Chemical Fungicides To Botryosphaeria Dothidea On Apple

Apple white rot, one of the important diseases in apple production, can make the trees weak, branches dead, fruits rot. The study was aimed to establish a rapid method based on conidial germination to evaluate the protective duration of different fungicides against apple white rot, to understand the treating time of different fungicides. At the same time, two-year field experiments were carried out to determine the control effect of Shuankang wettable powder to different types of Botryosphaeria canker of apple. The main results obtained are as follows:1. A rapid method, based on conidial germination to evaluate the protective duration of different fungicides against apple white rot, was established: the conidia harvested within 3 days after their appearing from the fruitlets, inoculated 10~15 days before, were most suitable for testing and, the cultivation time was 6 hours at 28 ℃in the dark wet condition.2. The protective duration of 0.5% Bordeaux mixture on the surface of fruitlets and of one-year branches of Fuji based on conidial germination rate were tested. The results revealed that under indoor conditions, the duration of 0.5% Bordeaux mixture with protection effect over 50% was 15 days on the surface of fruitlets, while it was only 7 days on the surface of one-year branches. Under field conditions, the effective duration of 0.5% Bordeaux mixture was more likely to be influenced by rainfall than sunlight. A single rainfall(10 mm) at 1, 3, 5 days after application of fungicides did not affect the effective duration of 0.5% Bordeaux mixture on the surface of fruitlets, but affected that on the surface of one year branches. Rainfall after 1 day of its applying had no significant effect on its effective duration, while rainfall after 3-5 days of its applying significantly reduced the inhibiting effect against spore germination.3. Under indoor condition tests, the duration of 80% mancozeb WP with protection effect higher than 50% was 5 days on the surface of fruitlets and one year branches. Under field conditions, the effective duration of 80% mancozeb WP was more likely to be influenced by rainfall than sunlight. A single rainfall(10 mm) at different time had significant effect on its effective duration on the surface of fruitlets and one year branches.4. In order to select an effective chemical fungicide in controlling Botryosphaeria canker of apple in field, this study measured the control effect of 80% carbendazim WP, 10% difenocon azole WG and Shuankang WP. Through the comparing trials in 2013 and 2014, the three chemical fungicides all showed good control effects. Shuankang had the best eradicated effect, followed by 10% difenoconazole azole WG and 80% carbendazim WP. In scuffing and without scraping trestments, Shuankang WP had best control effect among the three fungicides and had no significant difference beteen the two treatments. Through field control test of Shuankang WP in controlling Botryosphaeria canker of apple in field in 2014, the optimum concentration of Shuankang WP in controlling Botryosphaeria canker of apple in field was 40 times dilution. After smearing or spraying 12 times, the effect was more than 80%, so Shuankang WP could be used as an effective fungicide in the field.