There are two common types of banana leaf spot, namely yellow leaf spot and black leaf spot. In the past two years, it has occurred in banana orchards. The area affected by banana leaves often accounts for 20% to 40% of the total area of ​​the leaves. When it is severe, it is more than 80%. Most of the leaves of the diseased plants die dry and the plants cannot be sturdy, or the ears. If the fruit finger becomes smaller, the yield will be greatly reduced, the fruit quality will be reduced, and in severe cases, the yield will be reduced by more than 50%. Timely pesticide control is a top priority.
First, the initial stage of the disease yellow leaf spot disease is the appearance of small yellow-green disease on the upper surface of the third or fourth young leaves on the top of the plant. The diseased lines and the veins extend in parallel and form a yellow-green or yellow stripe. Expanded to form dark patches, watery, central brown or rust red, surrounded by a yellow halo, and then the central tissue of the plaque or stripes dried up. When the disease is severe, multiple lesions or streaks merge with each other, the surrounding tissue is necrotic, and the leaves become black and dry and die rapidly.
Black-spotted leaf spot appears at the beginning of the fully expanded third or fourth leaf on the lower surface of the vein, with tiny chlorotic spots. The spots expand into rust brown stripes, which then darken to dark red, brown or black. Seriously affected leaves, lesions or streaks merge, causing large areas of mesophyll tissue to be destroyed, turning into black and water stains, and finally the diseased leaves die quickly, dry, drooping, hanging upside down on the pseudo stem.
According to the pesticide network , leaf spot disease is a fungal disease, which is prone to epidemic under high temperature and high humidity weather conditions. Especially after typhoon and rain, the leaves cause more wounds and the disease is more serious. The most common occurrence of banana plantations is dense planting, no bud removal, poor soil drainage, weeds around the banana plantation, poor management, partial nitrogen application, and poor ventilation conditions.
Second, the prevention and control methods 1, strengthen the management of fertilizer and water: increase the application of organic fertilizer and phosphorus and potassium fertilizer, to avoid partial application of nitrogen fertilizer, and promote plant growth and robust. At the same time, when the new banana leaves are extracted, the roots are sprayed with nucleotides, Gaomei Shi, Shi Shibao or potassium dihydrogen phosphate to enhance the tree potential and improve its disease resistance.
2, pay attention to banana garden care: timely digging through the banana field drainage irrigation ditch, so that it can discharge irrigation; remove weeds in the garden, remove excess buds, reduce the humidity of the banana plant, keep the kneading surface dry and moist, to facilitate growth, reduce Onset.
3. Clean up the dead leaves of diseased leaves: For the plants with heavier incidence, timely remove the severely diseased leaves and dead leaves on the plants, remove the diseased leaves on the ground, remove them from the garden, reduce the source of bacteria, and make the orchard ventilate and reduce the humidity. To reduce the harm.
4, timely spraying prevention: in the early stage of the disease, after the removal of diseased leaves and after the storm and timely use of drugs, spray every 7 to 10 days, spray 3 times. According to the China Pesticide Network , the control agent can be selected from 64% antivirus 矾 800 times solution, 70% mancozeb 700 times solution, 77% can kill 1000 times solution, 25% must be 1000 times solution, etc. Alternate use, avoiding color to produce resistance and improve control.
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