What is the control method of shoot blight of Larix principis-rupprechtii?

Larix principis-rupprechtii shoot blight is a serious disease in Larix principis-rupprechtii forest and one of the forestry quarantine pests in China, so what is the control method of Larix principis-rupprechtii shoot blight?

I. symptoms of shoot blight of Larix principis-rupprechtii

The disease only occurred in the new shoots of the year. Generally, it starts from the main tip, and then gradually spreads downward from the withered tip at the top of the crown. The stem or stem axis gradually faded from light brown to brown and withered and thinned. The top of the shoot bent and drooped in the shape of a hook, and gradually defoliated from the curved part. In the later stage, only clusters of dead leaves remained at the top of the shoot for a long time, showing purplish gray.

The new shoots with late onset were lignified, the diseased branches did not bend and droop, but showed upright withered shoots, and all the diseased leaves fell off. Therefore, the branches above the diseased department withered and made the seedlings become apical seedlings. There are often fixed pieces of resin on the tip of the disease.

On the young trees, the new shoots of the following year also fell sick and withered, with lateral budding branchlets instead of the original main shoots, so that the disease occurred year after year, withered shoots became clumps, the crown showed broom-like clumps, height growth stopped, forming small old trees, or even the whole tree died.

2. control methods of shoot blight of Larix principis-rupprechtii

1. Remove the diseased branches and burn them centrally, which can reduce the susceptible sources.

2. Strengthen the management of forest garden, turn deeply and fertilize, enhance the tree potential and improve the ability of disease resistance. Open holes and fertilize in the tree holes in spring and autumn. The amount of fertilizer application can be considered according to the size of the tree. In general, 10-year-old trees can apply 300 grams of compound fertilizer at a time, once in Spring and Autumn. Fertilizers with high nitrogen content should be used in spring, and fertilizers with more phosphorus and potassium must be applied in autumn.

3. Brush the tree trunk with whitening agent. The formula of whitening agent is 5 kg of quicklime, 2 kg of salt, 0.1 kg of oil, 0.1 kg of bean noodles and 20 liters of water.

Spraying 200 times of 50% ethyl topiramate wettable powder or 200 times of 80% antibiotic EC in April, April to May and August respectively has a better control effect.

5. Curettage treatment. Vigorously scrape off the bark of the disease spot to the xylem, or make a deep cut in the vertical and horizontal direction of the disease spot, and then apply 3 wave stone sulfur mixture, or disinfect the solution such as 1% copper sulfate solution or 40% Fumei arsenic wettable powder 50 times.

6. Rational irrigation. Open holes and irrigate them in time in the dry season, and be sure to pour them thoroughly, and then water them again after they are dry; drain water in time in the rainy season; and pour frozen water before freezing. In the coming spring, if the soil is relatively wet, watering should be controlled, otherwise it should be watered thoroughly to prevent a large number of needles from falling off due to drought and weakening the tree. When watering, follow the principle of no dry, no watering, and watering thoroughly.