How to prevent and control pests and diseases of plum trees? Latest technical method tutorial

Plum trees are prone to pests and diseases under poor management conditions. In mild cases, it affects tree development, resulting in poor fruit quality and low yield; in severe cases, it causes tree weakening and a short lifespan, and the fruit becomes inedible. The main pests and diseases include the plum fruit sawfly, fruit borers, aphids, red spider mites, red spot disease, gummosis, etc. Now let's take a look at the pest and disease control techniques for plum trees!

Plum Red Spot Disease

[Damage characteristics] Plum red spot disease mainly damages leaves and also infects fruit. In the early stage of leaf infection, orange-yellow, slightly raised, nearly round spots with clear edges appear on the leaf surface. As the disease expands, the color deepens, and the mesophyll in the diseased area thickens accordingly, producing many small red granules on the surface, namely the fungal spore apparatus. By late autumn, the diseased leaves turn red-black, with the front side sunken and the back side protruding, the leaves curl, and small black granules appear, causing early defoliation. When fruit is affected, orange-red round spots appear, eventually turning red-black, with many dark red small granules on the spots. The fruit becomes deformed, inedible, and easily falls off.

[Control methods] 1. Thoroughly clean up diseased leaves and diseased fruit in the orchard and burn them in a centralized manner. Pay attention to drainage to reduce orchard humidity. 2. Before bud break, spray 3-5 degrees Beaume lime sulfur mixture. During the growing season, spray 50% carbendazim 600 times or 70% thiophanate-methyl 800 times, or 70% mancozeb 600 times every 10-15 days.

Plum Fruit Sawfly

[Damage characteristics] One generation occurs per year, with mature larvae spinning cocoons in the surface soil layer under the tree to overwinter and oversummer. When plum trees bloom the following year, they pupate into adults, fly and mate during the high temperatures at noon, and hide in flowers or under calyxes in the morning, evening, and on cloudy and rainy days. Eggs are laid within the calyx tissue, generally one egg per flower, rarely two. After the larvae hatch, they mostly bore in from the fruit surface and go straight to the fruit pit after entering the fruit. One larva damages only one fruit. When the kernel is completely eaten, the larva also becomes mature and leaves the fruit to oversummer and overwinter. Once the young fruit kernel is eaten, it stops developing and falls.

[Agricultural control] In early winter, turn over the tree dish to expose larvae in the soil to the surface so they freeze to death.

[Chemical control] 1. During the larval fruit-leaving period, spray 25% phoxim microcapsule formulation, or 48% chlorpyrifos 200-300 times on the ground. After spraying, lightly rake the soil to mix the pesticide with the soil evenly. 2. Spray when 80-90% of plum flowers have fallen: 5% beta-cypermethrin 2000 times, fenpropathrin 2000-3000 times, 2.5% deltamethrin 3000 times.

Plum Fruit Borer

[Damage characteristics] The plum fruit borer is a pest of the order Lepidoptera, family Tortricidae (more common in areas at 40-50° north latitude), and is the most serious pest damaging plum fruit, with a damage rate as high as 80%-90%. Affected fruit often exudes teardrop-shaped pectin at the insect hole, cannot continue to develop normally, and gradually turns purplish red and falls off. Because its tunnel is filled with red insect frass, it is also vividly called “red bean paste filling”.

[Control methods] The key periods for controlling the plum fruit borer are the peak adult stage and peak egg-laying stage of each generation, and the period when the first-generation mature larvae enter the soil. Spray 90% trichlorfon 0.8% solution, 50% malathion 1% solution, 50% dichlorvos. Before physiological fruit drop of plum trees, apply 50% phoxim 1%-1.5% solution broadly to the soil under the canopy. At the end of flowering (95% petal fall), when young fruit is the size of a wheat grain, spray the first application. Dichlorvos, decamethrin, fenvalerate, or fluvalinate can all be used, spraying once every 7-10 d. From the perspective of integrated control, biological agents such as Beauveria bassiana can also be used to treat the soil under the canopy. After autumn, all fallen fruit should be swept up to reduce the pest source for the following year.

Aphids

[Damage characteristics] Aphids mainly damage the young shoot leaves of plum trees. When young shoots are severely damaged, they curl, grow poorly, and photosynthesis is affected, leading to defoliation, affecting orchard yield and flower bud formation, and greatly weakening tree vigor.

[Control methods] 1. In early spring, combine with pruning, cut off damaged branches, and destroy them in a centralized manner. 2. Spray the tree: during the peak damage period, spray 50% dichlorvos emulsion 1%-1.5% solution, or 40% dimethoate emulsion 1%-2% solution, 50% malathion 1% solution, 50% phoxim emulsion 2% solution, 50% menazon wettable powder 1.5% solution. 3. Reasonably protect or introduce natural enemies.

Red Spider Mites

[Damage characteristics] The red spider mites damaging plum trees are mainly adult and nymph hawthorn spider mites. They suck sap from leaves and newly sprouting buds, causing new buds to fail to continue sprouting. After leaves are severely damaged, the whole leaf turns scorched yellow and falls off. In outbreak years, most leaves fall in July-August, sometimes causing a second bloom. Severely damaged plum trees not only fail to mature fruit that year, but also greatly affect flower bud formation that year and the yield of the following year.

[Agricultural control] According to the living habits of the hawthorn spider mite, in field management, rational intercropping should be carried out, the tree dish should be deeply turned or earthed up in a timely manner, pruning should be reasonable, and fertilization and irrigation should be appropriate. Folk methods can also be used, such as spraying garlic juice or mixing laundry detergent with lime sulfur mixture. At the same time, natural enemies should be protected to give play to their natural control effect on pests.

[Chemical control] 1. Dormant period: the purpose is to reduce the pest population base as much as possible. Before fruit trees sprout, spray 5% anthracene oil emulsion, 3-5 degrees lime sulfur mixture. In addition, before plum trees sprout in early spring, in conjunction with controlling other pests, thoroughly scrape off the raised bark and coarse bark on the trunk and main branches and burn them in a centralized manner. 2. After sprouting: control during the peak emergence period of overwintering female mites and when the first-generation eggs have all hatched. Use 30-degree lime sulfur mixture diluted with water to 0.8% solution, or 20% tetradifon wettable powder 0.6%-1% solution, 40% omethoate emulsion 1.5%-2% solution, 20% fenpropathrin 2% solution, 20% dicofol or 50% bromopropylate 1% solution. Various acaricides should be used in rotation to prevent resistance in the mites and improve control effects.

Plum Gummosis

[Damage characteristics] Gummosis is one of the more serious diseases occurring in plum orchards in recent years, and fruit growers often feel helpless about it. Gummosis mainly damages the living branches of plum trees. After being affected, the cortex of plum branches bulges in blister-like form, and then soft transparent gum continuously flows out. After the gum contacts the air, it turns reddish brown to tea brown, and after drying it becomes hard lumps. The cortex and xylem of the diseased area turn brown and necrotic, affecting tree vigor, and in severe cases some branches dry up or even the whole plant dies. This disease occurs year-round, especially in hot and rainy seasons.

[Agricultural control] 1. Focus on soil management: clean the orchard in a timely manner, loosen soil and build fertility, dig drainage ditches, prevent soil waterlogging, increase application of manure or bran fertilizer rich in organic matter and phosphorus-potassium fertilizer, and keep the soil loose to facilitate root growth, strengthen tree vigor, and reduce disease occurrence. 2. Timely control longhorn beetles and other trunk-boring pests to eliminate triggering factors. 3. Strengthen canopy care: prune reasonably, and never prune too heavily. When working in plum orchards, be careful not to damage the trunk cortex. Timely irrigation in dry and hot seasons can also effectively prevent the occurrence and damage of this disease.

[Chemical control] The suitable control period is May-June. Spray 12.5% diniconazole (tepuconazole) wettable powder 2000-2500 times solution, or 25% carbendazim substitute (Tanteling) wettable powder 500 times solution, once every 15 days, continuously 3-4 times. When applying, the solution should fully cover branches, trunks, leaves, and fruit until thoroughly wet.