Common Pear Tree Diseases and Pests: Types and Control Methods

The pear tree is a perennial deciduous fruit tree of the Rosaceae family, and its cultivated area and yield are second only to the apple tree. During its growing period, it may suffer from many diseases or pests. So, what diseases and pests of pear trees are there? How to control them?

1. What diseases affect pear trees? How to control them?

The main diseases of pear trees include valsa canker, Botryosphaeria canker, ring rot, anthracnose, brown spot, scab, and black spot.

1. Valsa canker

Symptoms: It damages branches and trunks. In the early stage, the diseased part is reddish-brown, oval or irregular, water-soaked, and slightly swollen. When pressed with a finger, the diseased part sinks, and the tissue becomes rotten. Sometimes reddish-brown sap overflows, giving off a sour mash odor. In severe cases, part or all of the tree dies.

Control: Prune and thin out in time to improve ventilation and light penetration and enhance plant stress resistance. Before disease onset, dilute 1 bottle of Husu Dajiangjun mother liquor with 30 kg of water and spray the tree body and ground thoroughly for disinfection, applying once every 15 days. After disease onset, cut down and burn diseased plants promptly to reduce the pathogen source.

2. Botryosphaeria canker

Symptoms: It damages branches, trunks, and fruit. In the early stage of branch and trunk infection, brown lesions appear on the cortex. When the lesion extends over more than half the circumference of the branch or trunk, the part above it dies. In the early stage of fruit infection, ring-shaped spots appear on the fruit surface, and the fruit then rots. When seedlings are infected, black-brown elongated wet lesions appear on the bark, after which the leaves wilt and the branches die.

Control: Strengthen management of young trees so they grow robustly and resist disease. Scrape and treat lesions promptly, applying Kuifuling mother liquor. In combination with winter and summer pruning, remove diseased branches and fruit in time and burn them in a centralized manner.

3. Ring rot

Symptoms: It damages branches, trunks, and fruit. In the early stage on branches and trunks, dark brown water-soaked spots form around lenticels and gradually expand into round or flattened-round shapes, with raised centers and a wart-like, hard texture. Severely affected trees become weak and branches die. In the early stage on fruit, brown water-soaked spots form around lenticels and gradually expand, becoming dark reddish-brown to light brown with clear concentric rings. The diseased fruit soon rots and gives off a sour odor.

Control: Clean the orchard well in winter to reduce and eliminate infection sources. Before bud break, scrape the lesions on branches and trunks clean and burn them to reduce the primary infection source. Apply eradicant fungicides during dormancy to directly kill the pathogen. Bagging fruit can effectively prevent fruit rot.

4. Anthracnose

Symptoms: It damages fruit and branches. In the early stage on fruit, small light brown water-soaked round spots appear on the fruit surface, becoming soft-rotted and sunken. In severe cases, most or all of the fruit rots, causing fruit drop or shrinkage into mummified fruit. On branches, round dark brown small spots first appear, later developing into oval or elongated shapes. The center of the lesion shrinks and sinks, and the cortex and internal tissues gradually die and turn dark brown.

Control: Do not apply excessive nitrogen fertilizer; increase phosphorus and potassium fertilizer to cultivate strong seedlings and improve the plant's own disease resistance. During the disease period, promptly remove diseased plant residues, diseased fruit, leaves, and branches. After vine removal, thoroughly clear diseased and fallen leaves and residues.

5. Brown spot

Symptoms: It damages leaves and fruit. In the early stage on leaves, small dark brown blisters and needle-like fine lines appear on the upper surface, and later the diseased leaves turn yellow and fall off. In the early stage on fruit, dark brown spots appear on the fruit surface, gradually expand, and the surface sinks, forming round or oval black lesions.

Control: Prune reasonably to strengthen tree vigor and improve ventilation and light penetration. In the early disease stage, use 50 ml of Aolike Sujing + 40 ml of Jinbei, diluted in 15 kg of water, applying once every 5—7 days for 2-3 consecutive applications. Remove fallen leaves to eliminate the infection source.

6. Scab

Symptoms: It damages young leaves, tender shoots, and young fruit. Leaf symptoms first appear on the upper surface as polygonal or nearly round chlorotic yellow spots, with radiating mold layers produced on the underside. In severe cases, it causes heavy leaf drop. Infected new shoots first show spindle-shaped lesions, and later the cortex in the diseased area cracks into rough, scab-like bark. Infected young fruit mostly falls early, or the diseased area becomes lignified and forms deformed fruit.

Control: Choose disease-resistant varieties. In late autumn and early winter, remove fallen leaves and fruit, and in early spring before pear trees bud, remove diseased shoots in combination with pruning. In the early disease stage, remove diseased shoots and diseased flower clusters, or in mid-May combine with promoting flower bud formation by girdling the base of large branches. Spray with a 400—600 times dilution.

7. Black spot

Symptoms: It damages fruit, leaves, and new shoots. When fruit is affected, one to several black spots appear on the fruit surface, and in the later stage the diseased fruit becomes deformed and cracked, causing fruit drop. When leaves are affected, young leaves are infected first, with brown to dark brown round spots that gradually expand; in severe cases, the diseased leaves scorch, become deformed, and fall early. When new shoots are affected, the lesions are round or oval, spindle-shaped, light brown or dark brown, slightly sunken, and easily broken.

Control: Choose and plant varieties with strong disease resistance. Fertilize reasonably to strengthen tree vigor and improve disease resistance. After leaf fall and before bud break, remove fallen leaves and fruit in the orchard, cut off diseased branches, and burn or bury them deeply in a centralized manner. At disease onset, dilute Sujing at 500 times and spray, applying once every 7 days.

2. What pests affect pear trees? How to control them?

The main pests of pear trees include pear aphid, pear curculio, pear longhorn beetle, oriental fruit moth, pear star caterpillar, and pear sawfly.

1. Pear aphid

Symptoms: It damages buds, leaves, tender shoots, and stems. Adults and nymphs gather on buds, leaves, tender shoots, and stems to suck sap. The damaged leaves curl longitudinally on both sides toward the upper surface into a tube shape and tend to fall early.

Control: Remove damaged curled leaves early and dispose of them centrally. After aphid eggs hatch, spray with 50% parathion emulsifiable concentrate at 3000 times dilution, 40% dimethoate emulsion at 2000 times dilution, or 50% dichlorvos emulsion at 1000 times dilution.

2. Pear curculio

Symptoms: It damages tender shoots, flowers, and fruit. When pear buds sprout and shoots emerge, adults feed on tender shoots and flower clusters, causing notches. After young fruit forms, they feed on the fruit, causing wide strip-like notches, and bite the fruit stalk. They lay eggs inside the fruit, and after the larvae hatch they bore and feed inside the fruit, causing early fruit drop.

Control: Pick up fallen fruit from the ground promptly and knock down damaged fruit to eliminate larvae. During the peak adult occurrence period, spray once every 10—15 days for 2 consecutive applications. Effective pesticides include 80% dichlorvos at 800—1000 times dilution, 50% phosphamidon emulsion at 2000 times dilution, and 90% trichlorfon at 1000 times dilution.

3. Pear longhorn beetle

Symptoms: It damages leaves and branches. Adults feed on leaves, petioles, veins, leaf margins, and the bark of tender branches to supplement nutrition. Larvae bore into and feed on the xylem of branches, making damaged branches prone to breaking in the wind.

Control: In the early stage of egg hatching, spray 50% parathion emulsifiable concentrate, malathion emulsifiable concentrate, monocrotophos emulsifiable concentrate, or various pyrethroid pesticides at conventional concentrations. During the adult emergence period, spray 50% parathion emulsifiable concentrate at 1500 times dilution. Promptly cut off pest-infested branches and burn or bury them deeply.

4. Oriental fruit moth

Symptoms: It damages pear buds, new shoot tender leaves, petioles, and fruit. First-generation larvae mainly damage pear buds, new shoot tender leaves, and petioles, with very few damaging fruit. Second-generation larvae cause increased fruit damage, and third-generation larvae cause the most severe fruit damage.

Control: In spring, scrape off the raised bark on the trees to eliminate overwintering larvae. Promptly remove damaged fruit and dispose of them centrally. Set up sugar-vinegar liquid (brown sugar: vinegar: liquor: water = 1:4:1:16) with a small amount of trichlorfon in the orchard to trap and kill adults. Spray 2.5% deltamethrin emulsifiable concentrate at 2 500 times dilution.

5. Pear star caterpillar

Symptoms: It damages flower buds and leaves. The larvae damage flower buds, flower buds, and leaves, and can occur twice a year.

Control: In early spring, scrape off old bark to eliminate overwintering larvae. During the emergence period of overwintering larvae, spray 90% crystalline trichlorfon at 1000 times dilution.

6. Pear sawfly

Symptoms: It damages fruit. The larvae first feed in a ring around the inside of the base of the calyx, and after the damaged area turns black, they bore into the fruit core, causing young fruit to dry up and drop. Before the fruit drops, the larvae crawl out and move on to damage other young fruit.

Control: During the egg-laying period, manually remove egg-bearing flowers and fruit and pest-infested young fruit. When adults emerge from the soil, spray the ground with 25% parathion at 300 times dilution, 25% phoxim at 300 times dilution, or 40.7% chlorpyrifos emulsifiable concentrate at 600 times dilution.

Summary: The main diseases of pear trees include valsa canker, Botryosphaeria canker, ring rot, anthracnose, brown spot, scab, and black spot. The main pests include pear aphid, pear curculio, pear longhorn beetle, oriental fruit moth, pear star caterpillar, and pear sawfly. Correct methods are needed for their control.