Kiwi yellow leaf disease symptoms
(a) nematode disease yellow leaf disease
The main occurrences in our county are northern root-knot nematode disease and peanut root-knot nematode disease. The underground roots have nodules at the beginning, the root skin looks normal, the surface of the large nodules is rough, and the later nodules and nearby roots are rotten and become black. Brown, dissected rotten nodules, visible milky white pear or lemon-shaped nematodes. After the plant is infected with nematodes, the upper part of the plant is short, the branches and leaves are yellow and weak, and the leaves and fruits are small and easy to fall. The pathogenic nematodes overwinter in the soil roots and insects inside and outside the insects. They can also be mixed with manure for wintering. The temperature rises in the next year, and the 2nd instar larvae invade from the root tip. The eggs are hatched in the soil for reinfection.
(2) Root rot yellow leaf disease
Root rot is a root-destroying fungal disease, and the bacteria overwinter in the roots and soil of the disease, and the disease occurs in high temperature and high humidity. The germs spread through tools, rain, water, and pests, and are invaded by lenticels and wounds. Mainly damage to the roots, causing the upper part of the plot to appear yellowing off the leaves, the tree body wilted and died.
(3) Deficient yellow leaf disease
1. Iron deficiency, light young leaves show pale yellow or yellow-white vein chlorosis, symptoms from the leaf edge to the main vein, the old leaves are normal, the old leaves are young leaves, so that all the leaves on the branches Loss of green and yellowing, even the leaves are chlorotic yellow or white, the leaves become thin, easy to fall off, the fruit is small and hard, and the peel is rough.
2. Magnesium deficiency, the symptoms appear on the old leaves, and the chlorotic spots are arranged along a certain distance along the leaf margin. The healthy green tissue on both sides of the main vein is wider, and the boundary between the green tissue and the healthy tissue is more obvious.
3. Zinc deficiency, the old leaves appear bright yellow veins chlorotic, the leaf margin is heavier, and the yellow veins between the old veins are more obvious. Sometimes the new shoots have small leaflets, and the small leaves show a narrow and long growth, which does not develop toward the width. Zinc deficiency not only affects the growth of the aboveground parts, but also affects the development of lateral roots.
Causes of kiwi yellow leaf disease
1. Yellow leaves caused by root damage: excessive watering, excessive rain, application of unfermented and decomposed organic fertilizer, fertilization on superficial, nematodes, these causes damage to underground roots, hindering the timely supply of nutrients and moisture in the aboveground parts. Yellow leaves appear in the lower part of the ground and above the ground.
2. Deficiency causes yellow leaves: The main fertilizers are magnesium and iron. However, in the years when the rain is heavy and the fruit trees are prosperous, the angle of the main branches of the tree is not open, and the branches are too large, which is easy to cause the branches to grow, and the comprehensive vegetative growth is too strong, causing some of the fruit trees to yellow due to lack of nutrition.
3. Yellow leaves caused by herbicide phytotoxicity: blind application of the drug or excessive application of the herbicide according to the instructions will cause herbicide damage and lead to yellow leaves. For example, glyphosate is a herbicide herbicide that rots whole weeds, including ground green leaves and underground roots, by internal conduction to the green tissue on the ground. Its impact on fruit trees is enormous. If glyphosate is used several times a year, the underground roots of the fruit trees will inevitably cause damage, resulting in malnutrition in the upper part of the earth and yellow leaves.
Kiwifruit yellow leaf disease prevention and treatment program
1. Combine trimming buds, thinning flowers and thinning fruits, cut off diseased vines, erase diseased weak buds, and leave flowers and fruits reasonably, so as to avoid excessive load of fruit trees, causing tree weakness and reducing self-resistance.
2, pay attention to balanced fertilization, combined with watering, in the application of nitrogen, phosphorus (phosphorus fertilizer should not be applied excessively)? Persimmon resistance and disadvantages (14) åº éªâ”ž 鼗蛄蛩峒兀 îŽæ‡Šç£• îŽæ‡Šç£• îŽæ‡Šç£• îŽæ‡Šç£• 7 7 7 kg. In the alkaline soil, ammonium sulfate, ammonium citrate, distiller's grains, vinegar grains and decomposed organic fertilizer, biological potassium, bio-organic fertilizer, etc. are added to enhance the tree potential and improve disease resistance.
3, the use of Chinese herbal medicine protective sterilization é“ å®‰ 安 and foliar fermented with Feng Fengsu.
The key use period of é“果安: spraying once in the sprouting stage, new shoot growth period (April-May), fruit expansion period of 6, 7 and 8 months, spraying the whole garden every month. The effect is good.
The key use period of Wofengsu: use in the new shoot period, after flowering, and fruit expansion period, and dilute each spray once according to 500-600 times liquid (using 350 kg per 350 ml of water).
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