Generally, before and after apple trees bloom, the weather is warm, and the temperature is 17~20 degrees. In case of continuous rain, it is easy to happen.
Dangerous symptoms:
It mainly harms leaves, shoots, young fruits and fruit stalks.
At the beginning of the disease, bright orange spots appeared on the front of the leaves, which gradually expanded to form round orange spots with red edges. When the disease is serious, dozens of diseased spots will appear on a leaf.
After 1~2 weeks, the surface of the lesion was covered with small yellow spots.
The new shoot is similar to petiole injury in the early stage, and the late stage is depressed, cracked and easily broken.
After the young fruit was infected, a nearly round lesion appeared on the surface of the fruit near the calyx depression, which was orange-yellow at first and then yellow-brown. Small spots were also produced on the surface of the lesion, first yellow, then black, and then a thin tubular rust spore apparatus was produced around the lesion. The growth of diseased fruit is stagnant and the diseased part is hard and deformed.
The following agents can be used: 3-5 baume stone sulfur mixture; 0.3% sodium pentachlorophenol 100 times solution. After the leaves are unfolded, the dark brown tongue coating on the thin tumor is sprayed 1 time before gelatinization. 1 After spraying, if it rains, spray the medicine for the second time immediately after the rain, and spray the medicine for the third time every 10 days. The following chemicals can be sprayed: 600-65438 times of 50% carbendazim wettable powder and 500-800 times of 80% mancozeb wettable powder; 15% triadimefon wettable powder 1000-2000 times solution; 20% Wei Xiuling EC 1500-3000 times; 25% o-amide suspending agent 1800-3000 times solution; 30% kresoxim-methyl suspension 1200-2000 times solution; 12.5% diniconazole wettable powder 1500-3000 times solution; 125% epoxiconazole SC1000-1250 times solution; 600-800 times of 40% flusilazole emulsifiable concentrate; 500 times solution of 65% zineb wettable powder/600-800 times solution of Kloc-0/50% thiophanate-methyl wettable powder; 70% mancozeb wettable powder 800 times solution +25% propiconazole EC 4000 times solution, it is suggested to add water-soluble fertilizer containing amino acids to the medicine, and the effect is better.