The recent humid climate and relatively high humidity in kiwifruit orchards are conducive to the reproduction of a variety of pathogenic bacteria, especially gray mold. Recently, there has been too much rain, high humidity in orchards, and some closed orchards, with very poor light transmission, resulting in a serious outbreak of "kiwi gray mold", causing a large number of fruit and leaves.
1. Main symptoms
When the humidity in the orchard is high and the duration is slightly longer, it is conducive to the occurrence of gray mold. After kiwifruit fruit is infected with gray mold, round or irregular brown disease spots are formed, and the early fruits are not easy to perform, and the fruits in the middle and late stages show local decay, with gray mold, causing fruit rot and shedding.
Second, the incidence of the disease
When the kiwifruit flowering period is subject to rainfall or high humidity conditions, pathogenic bacteria are easy to infect the flower apparatus and cause gray mold flower rot. Infected petals fall on leaves and fruits to further infect young fruits and leaves, aggravating the infection when wounded. It is easy to develop under high humidity conditions, the most suitable temperature for the growth of bacteria is 18~23 °C, the shelf surface is thick and not ventilated, insufficient light is prone to disease, and the orchard has high humidity for a long time. In case of continuous rain, the disease occurs seriously.
3. Current response measures
1. All kiwifruit orchards spray prevention and control, you can choose pyrimidin, putrefus, isomycourea and other fungicides spraying, seriously ill orchards spray every 7~10 days, continuous spray 2~3 times, agents should be used alternately to control the spread of disease;
2. For the fruits that have been diseased, they should be removed and picked up in time, and taken away from the orchard for deep burial or harmless treatment to reduce the source of infection;
3. Strengthen the management of summer shears and shelf surfaces, clean up crops between orchards, cut weeds, improve orchard permeability, and reduce orchard humidity;
4. Control the growth of branches and leaves, strictly use nitrogen fertilizer, avoid flood irrigation, increase the application of farm manure and medium and trace element fertilizer, and improve disease resistance.
4. Comprehensive prevention and treatment techniques
1. Keep the orchard ventilated and transparent and reduce the humidity of the orchard. As soon as the humidity rises, pathogenic bacteria are easy to multiply. There is a lot of rainfall in summer, and the branches grow fast, so we should pay attention to the work of picking and wiping buds and thinning branches in summer to prevent and control the growth of branches. In rainy weather, it is necessary to control weeds in orchards and improve orchard permeability.
2. Avoid partial application of nitrogen fertilizer. The use of nitrogen fertilizer will promote the growth of branches and reduce the disease resistance of fruit trees, so it is necessary to combine the law of fertilizer requirements of fruit trees and balance the supplement of various nutrient fertilizers.
3. Reasonable irrigation. Adopt water-saving irrigation, interlaced irrigation, orchard grass, etc. to reduce the number of irrigation times and irrigation volume, and control weeds before the rainy season to reduce the humidity of orchards.
4. Pharmaceutical prevention and treatment. Pharmaceutical options: 40% pyrimidamine 800 times, 50% humus li wettable powder 1000 times, acetamamide, 50% isomycourea wettable powder 1000~1500 times liquid, 10% polyantimycin 800 times, etc., pay attention to rotation of drugs, generally sprayed every 7~10 days, continuous spray 2~3 times.