Pests
Ash trees are susceptible to hazards such as ash, aphids, and long beetles. In early spring, the lime-sulfur mixture was sprayed before the buds of the ash tree sprout, and sprayed once every 10 days for two consecutive sprays to kill the overwintering bacteria. Use 50% carbendazim 800-1000 times liquid or 70% thiophanate methyl 800-1000 times liquid and any insecticide (such as 20% fenpropathrin EC 1000 times liquid or 5% cypermethrin EC 1500 times solution) to mix and apply trunks to prevent ash tree gum disease.
Disease
Brown spot
Symptoms: Brown spot disease mainly damages the leaves of ash trees, causing early leaf fall and affecting the growth of the trees that year.
The law of incidence: The pathogen of brown spot disease parasitizes on the front of the leaf, scattered polygonal or nearly circular brown spots, the center of the spot is grayish brown, 1-2 meters in diameter, and the large lesions reach 5-8 meters. The front of the spot is covered with brown mold spots, which are the fruiting bodies of the pathogen.
Control methods: Seedlings should be planted in time, and fertilizer and water management should be strengthened in the early stage to enhance the disease resistance of seedlings. Pay attention to nutrient balance and do not apply nitrogen fertilizer. In the autumn, clean the diseased leaves left on the ground of the seedbed, concentrate them, and bury them deep on the spot or burn them at a long distance to reduce the source of overwintering bacteria. From June to July, spray 1:2:200 times Bordeaux solution or 65% mancozeb wettable powder 600 times solution 2-3 times, and the disease prevention effect is good.
Coal pollution
Symptoms: Coal pollution disease is mainly caused by white wax aphids, scale insects, whiteflies and other pests. In addition to damage to leaves, it is also harmful to white wax branches. It blocks leaf stomata and hinders normal photosynthesis. In addition to causing early fall of white wax, the focus is It affects the annual growth of seedlings.
Occurrence law: The pathogenic bacteria of coal pollution overwinter on diseased leaves and spots in the form of mycelium or ascomycetes. Because the mucus excreted by aphids and scale insects will provide nutrients for the pathogenic bacteria of coal pollution, coal pollution usually occurs in large numbers after the occurrence of these two pests. Spring and autumn are the peak periods of coal pollution.
Prevention and control methods: through thinning and pruning measures, the trees are ventilated and light-transmissive, strengthen the tree vigor, and improve the tree's resistance to adversity. For timely control of aphids, scale insects, whiteflies, etc., imidacloprid or acetamiprid can be used, and carbendazim or thiophanate methyl can be mixed at the same time to effectively prevent the occurrence of diseases. Scale insects are a kind of pests that are difficult to control. You must catch the nymph's peak activity and use the medicine. You can use 800-1000 times liquid of wild scale insects, and generally one spray can achieve better control effects.