What are the integrated pest and disease control measures for pear trees?

The pear is a fruit with a very high water content, sweet and fragrant in taste, and with a certain nutritional value. There are many varieties of pears, and their requirements for the growing environment also differ somewhat. If management is improper during the growing process, they are very easily attacked by pests and diseases. Below, let us take a look together at integrated pest and disease control measures for pear trees.

I. Common pests and diseases of pear trees

1. Black spot

Pear black spot is one of the main diseases in the pear-producing areas of the south, mainly damaging pear leaves and fruit. Young leaves are affected earliest; at first, round black dots the size of a needle head appear, which later gradually expand into round or irregular lesions. The center of the lesion is grayish white, and the edge is dark brown; when humid, black mold forms on the surface of the lesion. Lesions on the leaf surface may join together into irregular large lesions, and some cause early defoliation. When young fruit is infected, round black spots the size of needle tips appear on the fruit surface, which after expanding become round or irregular lesions; the lesions are slightly sunken and cracked, with a black mold layer on the surface. When the disease is severe, the affected fruit drops early.

2. Pear rust

Leaf infection: at first, small orange-yellow, glossy spots appear on the upper surface of the leaves, then gradually expand into nearly round lesions that are orange-yellow in the center and pale yellow at the edge, with a layer of yellow-green halo on the outermost part and densely covered with small yellow granular dots on the surface. When the weather is humid, pale yellow slime oozes from them, and after drying, the small granular dots turn black. The lesion tissue gradually becomes thickened and fleshy, the underside of the leaf bulges, and the upper surface is slightly sunken; grayish yellow hair-like structures grow from the bulging parts.

3. Pear two-tailed aphid

The pear two-tailed aphid uses adults and nymphs to gather on buds, young leaves and young shoots to suck pear sap. In early spring, nymphs concentrate on green buds to cause damage, and invade the buds as the pear buds open. After the pear buds unfold their leaves, they move to young shoots and young leaves to cause damage. The damaged leaves curl inward from both sides of the main vein into a loose tube shape. When the damage is severe, it causes defoliation, weakens the tree vigor, and affects the current year's fruiting and flower bud differentiation.

4. Pear lace bug

Adults and nymphs suck sap near the main vein on the underside of leaves. The upper surface of damaged leaves shows pale white spots, and the underside of the leaves has dark brown excrement and secretions. When the damage is severe, the whole leaf becomes pale white, and the damaged leaves drop in large numbers early, causing pear trees to bloom a second time and affecting the yield of the current year and the following year.

II. Integrated pest and disease control measures for pear trees

1. Control methods for black spot

① Strictly clean the orchard, strengthen fertilizer and water management, improve tree vigor, and avoid excessive application of nitrogen fertilizer.

② During the growing season, promptly remove diseased fruit and diseased leaves and prune out diseased shoots, and burn them in a centralized manner. Bag susceptible varieties.

③ Before pear trees sprout, spray once with 3-5 degrees Baume lime sulfur mixture. After flower drop, according to rainfall and the control of other diseases, spray a fungicide every 15-20 d to protect the fruit. The agents include 1:2:200 Bordeaux mixture, 50% carbendazim wettable powder 500 times liquid, or 65% zineb wettable powder 500 times liquid.

2. Control methods for pear rust

① Keep away from Cupressaceae plants such as Chinese juniper and dragon juniper, and promptly prune away all diseased branches before wind and rain.

② In early to mid-March or early July, use 430 g/L tebuconazole suspension 3000 times liquid to spray once or twice on alternate hosts such as Chinese juniper.

③ Apply chemicals in early May; the following agents may be selected: 10% difenoconazole water-dispersible granules 1500 times liquid, or 80% zineb wettable powder 600-700 times liquid. To also control pear scab, 12.5% diniconazole wettable powder 3000 times liquid may be selected.

3. Control methods for the pear two-tailed aphid

In the early stage, remove the damaged curled leaves and burn them in a centralized manner or bury them deeply. From before pear buds open in early spring to the bud break and leaf unfolding stage, spray 2.5% cyhalothrin emulsifiable concentrate 3000 times liquid or 20% fenvalerate emulsifiable concentrate 2000 times liquid; in areas where natural enemies can be released, release ladybugs and green lacewings to feed on aphids. Protect hoverflies, aphid flies and other natural enemies.

4. Pear lace bug

① In winter, thoroughly eradicate weeds and fallen branches and leaves in the orchard, and burn them in a centralized manner to reduce insect sources.

② In September, wrap the tree trunks with grass to trap overwintering adults, and handle them together when cleaning the orchard.

③ From late March to early April, spread carbaryl toxic soil on the ground to kill overwintering adults; in late April, early May and early June, spray once each with 50% dichlorvos emulsifiable concentrate 1000 times liquid, 50% fenitrothion emulsifiable concentrate 1000-1500 times liquid, 50% malathion emulsion 1000-1500 times liquid, etc.