Prevention and control of yellowing and thinning of kiwifruit leaves

Kiwifruit yellow leaf disease, also known as yellowing disease, the affected plants, in addition to light green veins, the rest of the yellow chlorosis, small leaves, thinning leaves, weak tree potential, mostly in the branches and new leaves in spring.

Yellowing of kiwifruit

Causes: too much water in the garden, waterlogged roots; lack of iron or molybdenum and other elements; and root rot or too much fertilizer, fertilizer has not been fermented, damage to the root system leads to physiological deficiency and yellowing of kiwifruit.

Control measures: balanced fertilization of ①. To achieve nitrogen, phosphorus, potassium fertilization, a large number of elements and trace elements combined application. More attention should be paid to the application of organic fertilizer in alkaline soil. Full fruit period trees, per mu of maturity 4000 to 5000 kg of organic fertilizer, combined with deep ploughing to improve the soil. Plant clover in large rows and cover straw in small rows. Increase the content of soil organic matter to more than 2% and 3%.

② controls the yield and improves the tree vigor. Strictly thinning flowers and fruits, controlling the yield, the yield of trees in full fruit stage should be 2000kg to 2500kg per mu. Be on guard against overload to keep the tree strong.

③ is suitable for drainage and irrigation. Change flood irrigation into small border separate irrigation to avoid excessive irrigation and beware of stagnant water. Rain Water more years, can strengthen mid-ploughing, in case of continuous overcast and rain, to timely drainage, conditions, take seepage irrigation or drip irrigation. If the disease is serious, dig several deep 25cm pits around the roots of the diseased tree one week after the weather is fine (according to the situation of vegetables), and then irrigate with 50 times ferrous sulfate twice.

④ regulates soil pH. In alkaline soil with pH above 7.5, it is recommended that plants apply 1 kg of sulfur powder or 8% acetic acid solution to reduce the root standard pH value appropriately.

⑤ is reasonable topdressing. In the early stage of kiwifruit growth, ammonium nitrogen fertilizer such as ammonium sulfate or urea should be used mainly, and nitrate nitrogen fertilizer and ammonia bicarbonate should be used less. The application of iron fertilizer in soil should be mixed with mature organic fertilizer and humic fertilizer.