Apple's bitter pit disease prevention and control
Apple bitter pit, also known as bitter pit, is a physiological disease that often occurs during the ripening and storage of apples.
1. Etiology: Apple bitter pit disease is mainly caused by the physiological calcium deficiency of the tree. Trim overweight, partial application, late application of nitrogen fertilizer, excessive tree growth and poor fertility in the orchard are heavy. During the fruit growing season, large amounts of rainfall and excessive watering can easily aggravate the disease.
2. Symptoms: Symptoms start to appear when the fruit is near mature, and the storage period continues to develop. Lesions often occur near the top of the fruit, that is, near the fovea, while fewer occur near the fruit. The lesions of the flesh under the skin of the disease first occurred, and the skin of the lesion appeared round spots centered on the lenticels. This spot appears dark green in the green or yellow variety, dark red in the red variety, and the spot is slightly sunken. In the late stage of the disease, the flesh shrinks, and the epidermis necrosits. It will show dark brown spots. It is 2-3 mm deep and has a bitter taste. There are generally 3-5 lesions on light fruit, 60-80 heavy, all over the fruit surface.
3. Control methods: First, to strengthen the cultivation and management, reasonable pruning, additional farmyard fertilizer, prevent partial and late application of nitrogen, maintain a moderate tree vigor balance the growth and development; pay attention to the rainy season drainage, reasonable irrigation to prevent excessive accumulation of ammonia nitrogen. The second is to increase calcium fertilizer: soil organic bio-active calcium (Banzhou, Shandong Province) applied in spring or autumn. About 30 days after the apple has been grown, every 15 to 20 days, a 0.3% calcium nitrate solution is sprayed until about 20 days before fruit picking. The control effect is good. The drug is prone to phytotoxicity on leaves when the temperature is high, so be careful. It is best to add bio-organic active calcium when using autumn base fertilizer. The third is to strengthen storage management: Before apple storage, use 2% - 8% of calcium chloride or calcium nitrate solution to dip fruit.
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