| Valsa canker of apple, which is also known as the "cancer" of the apple trees, is a disease that damages the trees widely and heavily. It has become the restrictive factor to apple industry development. Several problems exist and remans solved, such as too many registered fungicides, the confusion in production application and the difference in efficacy evaluation exists in the control of the disease. In order to evaluate the control effect of fungicides in the market and provide useful information to fruit growers, the control effect of 10 kinds of fungicides including 9 kinds of registered ones on apple tree valsa canker and a unregistered one --propiconazole were compared on petri-dishes, wound healing, twig tests and field experiments; the healing situation of different shapes of wound were investigated at the same time. The research results are as following:1. Through the improvement of dual culture assays, the inhibitory effects of 10 kinds of chemical fungicides on mycelial growth were tested. The results showed that 3% dioctyldivinyltriamino glycine PA and 2.12% HA-Cu AS had the highest inhibitory effect. The bacteriostatic belts were both 5.00 cm, followed by 6.5% dioctyl divinyltriamino glycine AS, 45% propiconazole ME and 3.315% thiophanate-methyl + NAA PF.2. Effect on the wound healing of the fungicides were tested with the method of perforation, the results showed that the 3% thiophanate-methyl PA (made in Japan) was the best one, followed by the 3.315% thiophanate-methyl+NAA. The widths of callus tissue were 2.00 mm and 0.92 mm more than the control, respectively.3. In the twig tests, 3.315% thiophanate-methyl+NAA PF, 2.12% HA-Cu AS and 3% thiophanate-methyl PA (made in Japan) showed strong protective effects without any disease development. In the curative effect test, 3.315% thiophanate-methyl+NAA PF, 6.5% dioctyl divinyltriamino glycine AS, 45% amobam AS, 3% thiophanate-methyl PA (made in Shanxi) and 2.12% HA-Cu AS had better effects with average scar area less than 50 mm2. The control effects of 3.315% thiophanate-methyl+NAA PF and 6.5% dioctyl divinyltriamino glycine AS were 87.5% of the control and the area of scars were 1.6% and 2.2% of the control.4. With the inhibitory effects of 10 fungicides against Valsa mali and effects on wound healing. 3.315% thiophanate-methyl+NAA PF and the 2.12% HA-Cu AS were the best fungicides. Based on protective effect and the curative effect to the twig, 10 fungidides were ranked together again. 3.315% thiophanate-methyl+NAA PF was the best fungicide. Both rankings showed that 3.315% thiophanate-methyl+NAA PF was the best fungicide.5. The result of the field experiments showed that 3.315% thiophanate-methyl+NAA PF was the best chemical which had the best effect without any recurrent of the canker, followed by amobam with a control effect of 83.4%, while 1.8% Xin junan acetate showed the worst effect of 16.6%.6. When it comes to the healing situation of different shapes of wound, it was easy to form the callus on the two sides of the wound, the average healing width of the elliptic wound was 3.23 mm, which was the best one, so it should be the best choice in canker treatment.
|
PDF Full Text Request