First, the root rot of garden trees and its control methods. Root rot of garden trees is a kind of fungi and bacteria that propagate on seedlings and roots. Root rot of garden trees is mainly due to too much water, and trees grow in too humid places. Root rot mainly harms the roots of seedlings and can also occur in adulthood. The initial symptom is that the stems and leaves above the ground appear to be short of fertilizer and water, and the plants are short and grow poorly. When the diseased plant is pulled out, the fibrous roots are few and yellow-brown, and there are no obvious symptoms at the beginning of the taproot. However, with the aggravation of the disease, the plant grows worse and worse, and the bottom leaves begin to turn yellow and wither, and the dwarfing is more obvious. Finally, the whole plant leaves wither and the plant dies. Dead and diseased plants are easy to pull up from the soil, the fibrous roots have completely rotted, the main roots turn brown and gradually rot, and the root cortex is easy to peel off when squeezed by hand. When root rot is serious, the cortex tissue of trees will appear necrosis symptoms. However, this disease is hidden. Although it is serious enough to lead to the death of trees, the external observation of trees with large crown will not be reflected in the appearance of the crown, but some resin substances will flow out above the bottom of the trunk. After the seedling is sick, the symptoms are more obvious, its cortical tissue will slowly soften, then rot, and the seedling may wither. For the prevention of root rot, the method of improving wet growth environment is generally adopted. The disease is a fungal disease, and its occurrence is closely related to climate and soil conditions. High temperature and humidity, high soil viscosity, easy hardening, poor ventilation, easy to lead to root rot. Control method: 1, cutting weeds; 2. Spraying or watering the diseased plants with 50% carbendazim or 40% genfuning 1000 times solution; 3. For replanted plants, after removing the dead plants, water carbendazim or genfuning to kill germs, and then replant.
Second, the leaf spot disease of garden trees and its control methods. It is most serious in the spring with low temperature and the autumn with more rain. Leaf spot of garden trees often occurs on the leaves of trees. It often happens in high temperature and humid environment. At the beginning of the disease, brown spots will appear on the leaves, which will gradually expand into reddish-brown round calluses with the change of time. When the humidity is high, a gray mold layer will form on the surface of the affected part. When the disease is serious, it will eventually lead to yellowing of the leaves and early shedding. Prevention and treatment of leaf spot disease: from the early stage of the disease, the commonly used drugs are 700 times that of Sheng Da M-80 powder; 80% mancozeb 600-800 times; 70% thiophanate-methyl 1000 times; 80% ethylicin+propiconazole (ethylicin for leaf spot) 800- 1000 times; The control effect on leaf spot disease is ideal. Pay attention to the alternate use of drugs to avoid or delay the drug resistance of pests and diseases.
Anthracnose of garden trees and its control methods. Anthracnose of garden trees is one of the important diseases of branches and leaves, and it also harms the fruits of many trees and economic trees. At the beginning of the disease, the stem tip is dark brown spots, then it expands, sinks and turns yellow-brown, gradually turns light chestnut brown, and then turns gray for a long time. The diseased part circled around the branches for a week, and all the branches above the diseased spot died. At the early stage of leaf diseases, the spots about the size of needles appeared on the back of leaves, the leaves turned green, and the spots gradually expanded, showing yellow-brown and gray-white color wheel stripes, with a black band with uncertain width at the edge, which was clearly defined from the surrounding healthy tissues. High temperature, high humidity and poor ventilation are the preconditions for the occurrence of this disease. Prevention and control methods: remove diseased branches and leaves, and focus on deep burial or incineration. Spraying protective agents such as 80% mancozeb wettable powder (Sheng Da) 700-800 times solution, 1% bordeaux solution and 75% chlorothalonil 500 times solution before the onset of the disease. Spray 75% thiophanate-methyl WP 1000 times, 75% chlorothalonil WP 600 times, or 25% carbofuran WP 500 times, 25% benomyl EC 900 times, or 50% carbendazim 800- 1000 times, or 50% carbofuran WP. Once every 7 ~ 10 day for 3 ~ 4 times in a row, and the control effect is good.
Four, garden tree rust and control methods. Rust of garden trees is commonly known as yellow powder disease. Rust damages leaves and buds. There are nearly round yellow spots on the leaves. Symptoms are orange-yellow, flat powdery deposits on the back of macula, that is, pathogen summer spore piles. Before and after defoliation, brown spots are formed on both sides of the diseased leaves, that is, winter spore piles, which are buried under the epidermis of the leaves. It harms many kinds of trees and herbs, and it is a fungal disease of host transfer, which mainly harms leaves, shoots, petioles and buds. The leaves of severely damaged branchlets withered and even the whole plant died. The disease is very common, from small seedlings to big trees, especially small seedlings and young trees. According to the season, the rainy season is serious, starting from the basal leaves and gradually spreading upwards. After the pathogen invaded, orange papules first appeared on the back of leaves, followed by orange powder, which seriously affected the photosynthesis of leaves and caused defoliation and dead shoots, and the leaves appeared late and small in the second year. Rust occurs in June ~ 10, especially in autumn. Prevention and control methods: don't plant closely, pay attention to fertilizer and water management, and enhance plant disease resistance; Spraying triadimefon or triadimefon at the onset, and spraying again in the spring of the following year; Transfer host trees should not be planted together. You can use 1: 150 times Bordeaux mixture, 0.3~0.4 Baume sulfur mixture, 200 times sodium chloride solution, etc. , every 10 ~ 15 days 1 time.
Five, garden tree aphids and control methods. Garden tree aphids usually occur in spring. Once the temperature and humidity of the environment are suitable, the harm of tree aphids may occur. The first occurrence occurred in mid-March, and in April and May, aphids will cause harm by laying too many eggs, and aphids will leave their eggs in the new buds of trees, which will lead to trees turning yellow. For the prevention and control of aphids, we must take perennial protection, cut off the branches with eggs in winter and burn them, and spray a certain amount of pesticides such as imidacloprid 1000- 1200 times at the beginning of the disease, so as to kill the eggs as much as possible before laying eggs, which will get twice the result with half the effort. Spraying 10% ammonium bicarbonate solution, 0.5% ammonia solution and 2% urea solution outside the roots, spraying 1 time every 7 days or so, and spraying continuously for 2~3 times, has a good effect on controlling aphids.
Garden tree inchworm and its control methods. Garden tree geometrid is the main pest of Sophora japonica. The inchworm looks like a twig or petiole and feeds on leaves, which often seriously harms or damages trees. Generally, the first generation larvae begin to hatch in the first half of May, mature pupae in the second half of June, adults emerge and lay eggs from the second half of July to the second half of August, and the second generation larvae hatch one after another from the second half of July to the first half of September. For the control of inchworm, we should seize the time, that is, the larval stage, and spray 2000 when necessary. 50% Phoxim EC 4000 times, 20% Juma EC 4000 times, or 20% Pozzolana EC 4000 times to kill larvae.