Symptom
Grapes require a large amount of potassium, and potassium deficiency in grapes is common, which has a great impact on grape yield and quality. The symptoms of potassium deficiency in grapes vary with the growth and development stages of leaves. In the early stage of the growing season, the leaf margins of the basal leaves turn green and turn yellow, and brown necrotic spots appear on the leaf margins, which continue to expand and develop into the intervein tissue. The leaf margins curl and droop, and the leaves are deformed or shrunk. Whole leaves die.
At the end of summer, the surface of the old leaves at the base of the branches is directly exposed to the sun and turns purple-brown to dark brown, which is the so-called "black leaves". The black leaves begin between the veins, and if they continue to develop, they can extend to the entire surface of the leaves. After the plant is damaged, the leaves are small, the branches and vines are stunted, the fruit is small, and the sugar content is reduced. The whole plant is vulnerable to freezing damage or disease.
Etiology
The disease is serious when the soil available potassium content is below 40mg/kg. Potassium deficiency in grapes often occurs during the vigorous growth period of grapes. Normal garden soil available potassium content is about 150mg/kg, if it is lower than this amount, potassium deficiency often occurs in different degrees. Potassium deficiency is prone to occur when the soil is generally highly acidic and low in organic matter content, which is not conducive to the accumulation of potassium in the soil.
Prevention method
(1) Increase the application of organic fertilizer or enzyme bacteria large three-component compound biological fertilizer. In order to prevent potassium deficiency, more organic fertilizers should be applied appropriately, such as plant ash, decomposed plant straw and other farmyard manures.
(2) Spray 50 times of plant ash aqueous solution or 500 times of potassium sulfate solution and 300 times of potassium dihydrogen phosphate on the leaves.
(3) Apply 0.5-1kg of plant ash or 100-150g of potassium chloride to each grape plant, and the effect will be seen 5-7 days after application.
(4) Potassium fertilizer should not be applied too much, otherwise it will easily cause magnesium deficiency.
(5) It is recommended to spray 3.4% Chi·Inb·Brassica WP (Bihu) 7500 times liquid.
