Occurrence and control of pear root cancer

Damaging symptoms

The pathogen is a kind of bacteria, namely wild bacillus tumefaciens. The gall tumor was formed in the root and neck of the victim tree, and the size of the gall tumor varied greatly, from small to large, such as bean grain, spherical, hard, Lignification and rough surface. The diseased tree is stunted and looks like a small old tree with yellow and early fallen leaves and low yield. The disease is seriously damaged by seedlings and young trees.

Morbidity regularity

Overwintering with bacteria in diseased parts or residual roots and soil. Mainly invading the wound (insect injury, mechanical injury, etc.), the disease can be transmitted by transporting the diseased seedlings. Poor soil management is an important factor leading to root cancer. Soil consolidation, long-term stagnant water, can lead to poor ventilation. Poor soil and improper fertilizer and water lead to tree malnutrition, which can lead to root dysplasia and disease resistance, which is beneficial to the infection and expansion of root cancer. At the same time, the damage range of bacteria can be expanded with the flow of soil water.

Prevention and cure method

(1) strengthening the quarantine and treatment of seedlings

The transfer of seedlings from diseased nurseries should be avoided as far as possible. The seedlings can be disinfected with 2% lime water, or 0.5% copper sulfate solution, or 1000 times solution of 50% benzoammonium water for 15 minutes.

(2) strengthening cultivation and management

The application of organic fertilizer, trenching and drainage to improve soil is beneficial to the growth of root system and enhance the disease resistance of trees.

(3) scrape off the disease spot

Dig open the root and neck to find the diseased site, scrape off the spot thoroughly with a knife, and sterilize the wound with 2% limewater, and the scraped spot should be destroyed centrally. Larger wounds should be protected with paste or plastic sheeting.

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Occurrence and control of pear root cancer

Harmful symptoms

The pathogen is a kind of bacteria, namely wild bacillus tumefaciens. The gall tumor was formed in the root and neck of the victim tree, and the size of the gall tumor varied greatly, from small to large, such as bean grain, spherical, hard, Lignification and rough surface. The diseased tree is stunted and looks like a small old tree with yellow and early fallen leaves and low yield. The disease is seriously damaged by seedlings and young trees.

Morbidity regularity

Overwintering with bacteria in diseased parts or residual roots and soil. Mainly invading the wound (insect injury, mechanical injury, etc.), the disease can be transmitted by transporting the diseased seedlings. Poor soil management is an important factor leading to root cancer. Soil consolidation, long-term stagnant water, can lead to poor ventilation. Poor soil and improper fertilizer and water lead to tree malnutrition, which can lead to root dysplasia and disease resistance, which is beneficial to the infection and expansion of root cancer. At the same time, the damage range of bacteria can be expanded with the flow of soil water.

Prevention and cure method

(1) strengthening the quarantine and treatment of seedlings

The transfer of seedlings from diseased nurseries should be avoided as far as possible. The seedlings can be disinfected with 2% lime water, or 0.5% copper sulfate solution, or 1000 times solution of 50% benzoammonium water for 15 minutes.

(2) strengthening cultivation and management

The application of organic fertilizer, trenching and drainage to improve soil is beneficial to the growth of root system and enhance the disease resistance of trees.

(3) scrape off the disease spot

Dig open the root and neck to find the diseased site, scrape off the spot thoroughly with a knife, and sterilize the wound with 2% limewater, and the scraped spot should be destroyed centrally. Larger wounds should be protected with paste or plastic sheeting.

Integrated control of common diseases and insect pests in winter

In order to reduce the occurrence of diseases and insect pests in the following year, comprehensive control combined with winter pruning according to different overwintering places of diseases and insect pests can not only reduce the degree of garden plant diseases and insect pests, but also has the advantages of labor-saving, medicine-saving, good effect and so on.

Disease prevention and cure

1. For big leaf Euonymus leaf spot, golden leaf privet leaf spot, golden leaf privet coal pollution, crape myrtle coal pollution, rose coal pollution, rose black spot, green peach perforation and other diseases. As most of their pathogens overwintered on litter, it is necessary to remove deciduous weeds in garden green space in time in winter and concentrate on deep burial or high temperature retting manure, which can eliminate a large number of overwintering disease sources.

two。 For diseases such as powdery mildew and anthracnose of Euonymus tomentosa, their pathogens are mostly parasitic on branches and leaves to survive the winter. Combined with winter pruning, cut off the branches damaged by bacteria, and spray Baume 5 to 8 degrees stone sulfur mixture again after cutting.

3. For the diseases of transferred hosts, such as begonia-juniper rust and pear-juniper rust, the spore horn formed by mycelium on juniper overwintered after winter. The control method is to cut off the spore horn of juniper, and when the spore pile is mature in late winter, spring and early winter, spray 1 ∶ 2 ∶ lime Bordeaux solution to inhibit the spore heap to produce microspores.

4. For turfgrass powdery mildew, rust, brown spot and other diseases, their pathogens overwintered on diseased leaves. The control method is to remove the fallen leaves, withered grass layer and diseased body on the lawn, and reduce the source of bacteria.

5. Populus tomentosa scab, Fusarium wilt of Ligustrum lucidum, etc., the pathogen usually overwinters in the soil, mole cricket, kowtow worms, nematodes and so on can spread the pathogen to expand the harm. The control method is to cut off the diseased branches and leaves and deal with them centrally; organic fertilizers such as barnyard manure and compost irrigated in winter should be fully mature, or mixed with pesticides, which can kill mole cricket and kowtow worms overwintering, so as to reduce the spread of the disease; at the end of winter, 5 Baomei stone sulfur mixture can be sprayed to prevent it.

6. The pathogens of root cancer of Populus tomentosa, rose root cancer and paulownia arbuscular disease overwintered on diseased plants or in tumor or in soil. Prevention and treatment methods: combined with pruning, remove the diseased tumor and arbuscular branches, then disinfect the wound with 1000 units of agricultural streptomycin or oxytetracycline; dig out the dead trees, and sprinkle 50 grams to 100g of sulfur powder, ferrous sulfate or bleach powder to disinfect the soil.

Pest control

1. Pests overwintering with cocoons

Most of the insect pests of diamondback moths spend the winter with cocoons. For example, the yellow diamondback moth overwinters with mature larvae in branch bifurcations, the flat diamondback moth overwinters with cocoons in underground crevices, the brown green thorn moth overwinters with cocoons in the shallow soil of branches and roots, and the double-toothed green diamondback moth overwinters with cocoons in the base of tree trunks, scars or rough bark cracks.

Prevention and cure method

Combined with winter pruning, cut off the cocoon branches and burn them centrally.

In the cocoon formation period of diamondback moth in winter, remove or break the cocoons on the branches (yellow diamondback moth, double-toothed green diamondback moth), dig out the cocoons in the shallow soil around the tree base (brown edge green diamondback moth), and reduce the overwintering insect source.

two。 Overwintering as larvae

Most of the pests of ⑴ overwintered as young larvae in bark seams, litter and holes; brown leaf rollers, pear heart borer, peach borer, etc. overwintered at the seams, warping skins, tree scars or saws of the damaged plants; the yellow poplar silk borer made a thin cocoon in the nest made of two leaves of the host; and the pear star caterpillar overwintered in the thick skin seams of the branches and main branches of the damaged plants.

Prevention and cure method

Clean up the fallen leaves thoroughly in winter, cut off the dead branches and burn them centrally. In winter, the bark, branches and cocoon trunks inside the cracks are scraped and painted white. Eliminate the source of overwintering insects.

⑵ Spodoptera litura, Helicoverpa armigera and other larvae overwinter in loose soil.

Prevention and cure method

Combined with ploughing the soil to eliminate overwintering larvae. The lawn combined with winter irrigation applied carbofuran or phoxim particles to kill the overwintering larvae.

⑶ overwintered as larvae in damaged branches, such as rose stem wasp, white wax stem wasp, aromatic wood bark moth, white poplar through-wing moth and so on, while Sophora pseudoacacia overwintered in damaged branches and seeds.

Prevention and cure method

① rose stem wasp can be combined with winter pruning to cut off the damaged branches. If it is found that the worm has been eaten into the root, it can use a syringe to inject 5ml to 10ml of imidacloprid EC into the wormhole, and immediately seal it with soil to kill the remaining larvae.

② white wax Harrington stem wasp can cut off the damaged branches and burn them centrally.

③ wood beetle moth pests often drill the worm path in the branches, rough bark and wounds, and can use wire hooks to kill the larvae in the path.

3. Overwintering as pupa

⑴ diamondback moth and ulnar moth pests, such as frost diamondback moth, grape diamondback moth, bean diamondback moth, Sophora pseudoacacia, locust, silk cotton and so on, all overwinter as pupae in the soil.

Prevention and cure method

Can be combined with ploughing the soil to remove weeds. Artificial excavation of pupae to kill overwintering pupae. 50% phoxim was sprayed on the ground around the host to poison the pupae in the soil.

⑵ lamp moth, boat moth pests, such as American white moth, human striped light moth, red edge lamp moth, Robinia pseudoacacia feather boat moth, Yang fan boat moth and so on. Most of the pupa overwintered under the old bark of the trunk, cracks in buildings, eaves, holes, bricks and sundries, etc.; citrus butterflies pupated in the air in the branches.

Prevention and cure method

Thoroughly remove weeds and debris from the green space and the surrounding environment. Destroy the habitat of overwintering pupae, combined with ploughing the soil to eliminate overwintering pupae.

4. Egg overwintering aphids often winter with eggs in the bark crevices and bud armpits, such as autumn four-veined cotton aphids overwintering with eggs on branches; mites winter with eggs or fertilized female adults, such as Hawthorn spider mites and fertilized female adults in bark crevices or under soil; wheat mite overwinters as adults under the eaves of buildings near the lawn, under the warped bark of trees, and under weeds. The tetrapod mites causing wrinkle leaf disease of Populus tomentosa overwintered with eggs among the bud scales of Populus tomentosa and so on.

In addition, the gypsy moth overwinters as fully developed larvae in the eggs, and the eggs are on the shady side, bark and stone cracks at the base of the trunk; the spotted wax cicada generally lays eggs on the sunny side of the trunk.

Prevention and cure method

Remove diseases and insect pests in winter, remove weeds and concentrate on burning. Artificial scraping of eggs; scraping off rough skin, warping dead skin, killing overwintering eggs. The trunk is painted white and kills the overwintering eggs in the cortex.

5. Overwintering as adults

Most of the bugs overwinter as adults, such as tea wing bugs, sesame skin bugs, point bee bugs, red ridge bugs and other adults in grass, litter, eaves, walls and haystacks. Elm green hair firefly leaf beetle, willow blue leaf beetle and so on also spend the winter as adults in hidden places such as eaves, wall seams, soil, and weeds under masonry.

Prevention and cure method

Remove litter, weeds and debris, concentrate on treatment, and kill overwintering adults. Artificial hunting and killing of adults

6. Overwintering with protective capsule

The big coir moth and the small coir moth overwinter as larvae on the hanging branches in the protective capsule, and the silkworm moth generally overwinters on the branches as a pupa cocoon.

Prevention and cure method

After defoliation in winter, bags and cocoons are removed manually to eliminate larvae and cocoons.

(the author's unit is the Garden Plant Protection Center of Huabei Petroleum Huajia Integrated Service Office)