(1) powdery mildew
Powdery mildew is a common disease on broad-leaved trees and is distributed all over the world. There are many kinds of powdery mildew with strong host specificity. Powdery mildew mainly harms leaves, shoots, buds, flower stalks and branches. After infection, white powdery substances (hyphae and pollen spores) are formed on the surfaces of leaves and shoots. In the later stage, the mildewed layer of white powdery substance turned to light gray, and small black spots with closed capsules appeared in the affected area. The leaves of the affected plants are uneven, curly and the branches are deformed. In severe cases, the flowers are small and few, and the leaves shrink and dry, which affects the growth and even death of plants. Powdery mildew is a fungal disease, which harms rose, rose, apple, peony, pear, walnut, chestnut, persimmon, mulberry, grape, cotinus coggygria, peach, plum, cherry, hawthorn and other trees. Pathogens overwinter on diseased buds, diseased branches or fallen leaves by mycelium or conidia. With the help of wind and rain, conidia can be reinfected many times a year, which has strong adaptability to temperature and humidity, especially in early summer and late autumn.
Figure 1 powdery mildew
Prevention and control methods:
(1) combined with pruning, cutting off diseased branches and leaves, and centralized burning.
(2) Strengthen the cultivation management, increase the application of phosphorus and potassium fertilizer, control the nitrogen fertilizer, make the plants grow healthily and improve the disease resistance.
(3) At the initial stage of the disease, 25% triadimefon wettable powder, 800% thiophanate-methyl wettable powder or 800 ~ 1000% carbendazim wettable powder can be sprayed.
(2) Rust
Fungal diseases mainly damage leaves and buds. After leaf spreading in spring, the disease began, and yellow rust spores were produced on the back, petiole and vein of leaves. After the orange rust spores protrude from the epidermis, they spread out and invade the plants. In early summer, it spread in large quantities, forming orange or yellowish brown powdery summer spore piles, which turned the branches and leaves green and yellow, and the diseased spots were obviously raised. In severe cases, the leaves of the whole plant die, or the buds wither and fall off.
1. Common types
(1) Apple Rust
Also known as apple rust and apple scab. In addition to harming apples, it can also harm Malus plants such as Begonia, Fructus Crataegi, bonus and hawthorn. Apple rust is a parasitic fungus. Its main host is juniper, and there are juniper, juniper, juniper, juniper, juniper and juniper. Generally more common in areas with hosts.
(2) Pear rust
Also known as pear scab, it can harm pears, papaya, hawthorn, begonia, etc. The host plants are juniper and cypress (Figure 2).
Fig. 2 Pear rust
(3) Rose rust
It is widespread in China's rose producing areas, mainly damaging leaves, buds, branches and fruits. In addition to harming roses, it can also harm roses, roses and many plants of the genus Rosa. Pathogens overwinter on diseased plants and fallen leaves and spread through airflow.
2. Prevention and control methods
(1) Avoid the mixed planting of ornamental trees such as begonia and hawthorn with Sabina vulgaris or other host plants, and cut off the infection chain. In the scenic spot, the overwintering gall of juniper trees should be cut off, and 3 ~ 5 Baume sulfur mixture or 1: 1: 160 bordeaux mixture should be sprayed on juniper trees during the host germination stage.
(2) chemical control. Spraying 25% triadimefon wettable powder 1500 times before and after flowering. In the growing season, combined with other diseases prevention and control, more than 200 times dosage of Bordeaux solution, 700 times dosage of 65% zineb solution and 600-800 times dosage of 70% thiophanate-methyl solution were sprayed.
(3) Brown spot disease
Fungal diseases mainly harm leaves (Figure 3). After infection, the lesions on the leaves are round or nearly round, purple-brown, and turn black in the later stage. The boundary between diseased and healthy parts is clear. In severe cases, most diseased spots can be connected into pieces, which makes the leaves yellow and fall off, affecting flowering. It mainly harms plum blossom, begonia, rose, rose, peony, peony, clove, rhododendron and magnolia grandiflora. Brown spot overwinters in dead leaves or soil with mycelium or conidia. With the help of wind and rain, it began to happen in early summer and was serious in autumn. High temperature and humidity, too dense plants, insufficient light, poor ventilation and continuous cropping of soil are all conducive to the occurrence of diseases.
Fig. 3 brown spot disease
Prevention and control methods:
(1) Remove diseased branches and leaves, and burn them centrally to reduce the source of germs.
(2) Strengthen management, pay attention to ventilation and avoid close planting. If the groundwater level is high, dig ditches to drain water to reduce humidity.
(3) During the onset, 400-600 times of 80% mancozeb wettable powder, 500 times of 50% carbendazim wettable powder or 500 times of 25% chlorothalonil can be used. Spray 1 time every 10 ~ 15 days, 2 ~ 3 times, and spray the liquid medicine evenly on both sides of the leaves.
(4) Black spot disease
Fungal diseases can damage leaves, petioles, shoots and pedicels, but mainly damage leaves. At the beginning of the disease, it was a brown radial lesion with obvious edge, with a diameter of 5 ~ 10 mm and black spots on it. In severe cases, leaves wither and fall off in the early stage, which affects growth. Harm roses, osmanthus fragrans, pears, walnuts, magnolia grandiflora, etc. Overwintering in diseased leaves, dead branches and soil with hyphae or conidia, or hiding in plant bud scales, leaf scars and stem tips. Early summer and late autumn are the peak periods. Conidia spread through wind and rain, expanding infection. Too much rain, high humidity, insufficient light and poor ventilation are all conducive to the onset.
Prevention and control methods:
(1) Cut off diseased branches and leaves in autumn and winter, remove underground fallen leaves and residual plants, and burn them centrally to reduce the source of bacteria.
(2) Selection of disease-resistant and disease-tolerant varieties.
(3) Strengthen cultivation management, strengthen tree vigor, improve disease resistance, pay attention to shaping and pruning, ventilation and light transmission, pay attention to drainage in rainy season and reduce humidity.
(4) Spraying 500- 1000 times solution of 50% carbendazim wettable powder, 70% thiophanate-methyl wettable powder 1000 times solution and 75% chlorothalonil 1000 times solution on the leaves. 10 ~ 15 days 1 time, * * * 2 ~ 3 times.
(5) Anthracnose
Fungal diseases mostly occur at the tip and edge of leaves, and branches will also be damaged, causing shoots to wither. At the initial stage of the disease, it is a round or semi-circular lesion with gray or light brown center and dark brown edge. In the later stage, the lesions are covered with black spots, which are scattered or arranged in a wheel shape, that is, the umbilical point of the pathogen. The disease mainly harms camellia, orchid, magnolia grandiflora, rubber tree, jasmine, smiling face, plum blossom and so on. Pathogens overwinter in plant residues or soil in the form of mycelium, and conidia are spread by wind, rain and water. And invade from the wound. In the rainy season, the disease is more serious, making the whole leaf black, affecting the growth, and in severe cases, the whole plant dies (Figure 4).
Fig. 4 Anthracnose
Prevention and control methods:
(1) Select excellent varieties with disease resistance.
(2) Cut off the diseased leaves in time and burn them.
(3) Keep ventilation and light transmission, and minimize the water on the leaves when watering.
(4) Spraying 50% carbendazim wettable powder 800- 1000 times, 70% thiophanate methyl 800- 1000 times and 75% chlorothalonil 500 times.
(6) Coal stain
Also known as soot disease, it widely occurs in flowers, trees and shrubs, especially in greenhouses and greenhouses. Because the leaves of diseased plants are covered with black mold layer, it not only affects the ornamental value of flowers and trees, but also affects the photosynthesis of flowers and trees, resulting in the weak growth of plants and early defoliation. The disease damages leaves and sometimes shoots and flowers. It can harm many ornamental plants such as camellia, jasmine, boxwood, Chinese rose, Prynne, Ivy, Pittosporum, Osmanthus fragrans, Milan, Gardenia, Ilex cornuta, Forsythia suspensa, Hibiscus hibiscus, Paeonia suffruticosa, Magnolia grandiflora, pomegranate, oleander, citrus and honeysuckle. The disease is caused by a variety of coal-contaminated bacteria, which are mainly parasitic on the feces and secretions discharged by aphids and scale insects. Therefore, when these pests occur on flowers and trees, they provide nutrition for coal-contaminated bacteria and are the direct cause of the disease; In addition, it is easy to get this disease in shade, high humidity and poor ventilation and light transmission.
Prevention and control methods:
(1) Controlling aphids, scale insects, whiteflies and other pests is the fundamental measure to control sooty blotch.
(2) Proper pruning is beneficial to ventilation and light transmission, enhancing the tree potential and reducing the incidence.
(3) When the condition is serious, 0.3 baume stone sulfur mixture can be sprayed.
(7) bacterial perforation of peach
It mainly harms leaves, branches and fruits. In the early stage, the lesions on the leaves were waterlogged spots, light brown, and gradually formed round or nearly round brown or purple brown lesions, with light yellow halo at the edge of the lesions. In the later stage, the tissue around the lesion was corked, which led to the shedding of the lesion tissue and the formation of perforation. There is necrotic tissue residue at the edge of the point, and the diseased leaves turn yellow and fall off early. After the branches were damaged, light brown waterlogging spots began to appear, which gradually expanded into spindle-shaped sunken ulcers and yellow bacteria overflowed. The pathogen is bacteria, which overwinters in branches or diseased buds and spreads through insects or wind and rain. In addition to harming peaches, it can also harm peach, apricot, plum, cherry and other tree species (Figure 5).
Fig. 5 bacterial perforation of peach
Prevention and control methods:
(1) Strengthen cultivation management, strengthen tree vigor and improve disease resistance.
(2) Remove dead branches, fallen leaves and diseased fruits in winter and spring, cut off diseased branches and reduce bacterial sources.
(3) Spraying 5 Baume lime-sulfur mixture before germination.
(4) At the initial stage of the disease, spray 95% Bacillus 500-800 times, or streptomycin 50- 100 mg/kg, 77% chlorhexidine wettable powder 400-800 times, 50% Tuyete wettable powder 800- 1200 times, etc.
(8) Fungal perforation of peach
It is caused by fungal infection. In severe cases, it can cause leaf perforation, early shedding and dead branches.
1. Common types
(1) brown spot perforation
Can harm peaches, plums, apricots, plum blossoms, cherries, persimmons, etc. The main damaged parts are leaves, branches, buds and fruits. After the leaves are damaged, purple-brown spots first appear, and then gradually expand into round, slightly wheel-shaped spots with purple-brown edges. The center of the lesion is grayish white or brown, and there are occasional grayish brown molds on both sides of the lesion in the later stage (Figure 6). Lesions can fall off to form perforations with neat edges. The pathogen overwinters in the tissue of stem apex disease with mycelium.
Fig. 6 Brown spot perforation
(2) perforation of mildew spots
Can harm peaches, peaches, plums, apricots, cherries, etc. Harm leaves, branches, buds and fruits. Leaf injury is light yellow, round or irregular in the initial stage, turns brown in the later stage and finally pierces. After infection, the young leaves did not form perforation, and most of them were burnt. When wet, white mold will grow on the back of the lesion. Most of the damaged branches are centered on buds, forming long oval lesions with purple-brown edges, cracks and glue flow. The fruit is damaged, the lesion is purple or reddish brown at first, and the center is sunken. The disease overwinters with hyphae and conidia in damaged branches or buds.
2. Prevention and control methods
(1) Strengthen management, increase application of organic fertilizer, phosphorus and potassium fertilizer, reasonable pruning, ventilation and light transmission, enhance tree vigor and improve disease resistance.
(2) Remove diseased leaves, cut diseased branches and reduce bacterial sources.
(3) Spraying 5 Baume lime-sulfur mixture before germination.
(4) Spraying 500 times of 65% zineb wettable powder and 500 times of 58% erysipelas manganese and zinc at the initial stage of the disease. Spray every 15 ~ 20 days 1 time, and spray continuously for 2 ~ 3 times.
(9) Peach Leaf Shrinking Disease
When the leaves are damaged, the diseased leaves become thicker and curl inward along the leaf edge, the diseased leaves expand and contract, the meat becomes fat and brittle, the leaves are uneven and turn reddish brown, a silvery white powdery mildew layer appears on the front of the leaves, and then the diseased leaves turn black, die and fall off. The diseased part of the new shoot is swollen, yellow-green or gray-green, the internodes are shortened, the leaves are curled, and in severe cases, the branches die. The flower organ is twisted, the young fruit is deformed with cracks and scars, and the affected part of the big fruit is red and swollen (Figure 7). This disease will harm peaches, peaches, flat peaches, almonds and nectarines. Cold and high humidity are conducive to the onset. Spores overwinter on bark and bud scales and dive into scales, while ascospores or spores overwinter on peach bud scales and branches.
Fig. 7 Peach Leaf Shrinking Disease
Prevention and control methods:
Spraying 3 ~ 5 Baume lime-sulfur mixture at the beginning of (1) bud is even and thoughtful, and the effect is good.
(2) Spraying 1 times of 6% barium polysulfide before germination and 3% copper sulfate after defoliation has a good effect.
(3) before the botrytis cinerea layer is produced, the diseased leaves are removed and the diseased tips are cut off.
(4) Spraying 75% chlorothalonil 600 ~ 1000 times solution and 80% zineb 600 times solution at the initial stage of the disease.
Three. Root diseases and their control
There are not many kinds of garden root diseases, but their harm is often devastating. The symptoms of root disease mainly include gall, hairy roots and cortex rot; The above-ground part first showed that the color of the branches was wrong, then the leaves unfolded slowly, the deformation of the leaves was small, the early leaves withered, and finally the whole plant died. The disease of the big tree can be delayed for several years without being discovered, and the disease of the small seedling usually dies that year.
(1) Root cancer
Also known as crown gall disease, it is a worldwide disease. This is the case all over China. There are about 665438+300 species in 0 families, including peach, pear, apple, cherry, plum, elm leaf plum, rose, Siraitia grosvenorii, walnut, cypress, willow, ginkgo and rubber tree. Root cancer mainly occurs in the root neck, sometimes in the taproot, lateral root or trunk and branch of the above-ground part. Tumors of different sizes and shapes were formed in the affected areas (Figure 8). The primary small tumor is gray or flesh-colored, soft and smooth, and then gradually turns brown or dark brown, with hard texture, rough surface and cracks, and the internal tissue of the tumor is disordered. Pathogens can survive in root nodules and soil host residues for more than 1 year. Bacteria invade and spread through irrigation water or rainwater, underground pests, seedlings, cuttings, grafting materials and tools, and wounds. High temperature and high humidity are most conducive to the onset. There are many wounds in the roots of seedlings, and the diseases are serious.
Fig. 8 Root cancer
Prevention and control methods:
(1) Strict quarantine, it is forbidden to leave the nursery and destroy the sick seedlings. Suspicious seedlings are soaked in 1% copper sulfate aqueous solution for 5 minutes, then soaked in 50 times lime water 1 minute, or soaked in streptomycin 100 ~ 200 mg/kg for 20 ~ 30min for disinfection, and then washed with clear water before planting.
(2) Select the areas not infected with root cancer to establish nurseries, otherwise it will take more than 3 years of rotation.
(3) Prevent seedlings from producing various wounds and prevent underground pests and nematodes.
(4) Before transplanting the seedlings, soaking the roots or cuttings with the bacterial suspension of Agrobacterium radiobacter K84 (10 6 cells /ml) can prevent the root cancer of drupes and roses.
(5) If a diseased plant is found, it should be pulled out in time. For newly diseased plants, the diseased tumor can be removed with a knife, and then the wound can be smeared with lime milk or Bordeaux pulp, and the pruning tool can be disinfected with 1% formaldehyde.
(2) Rhizoctonia solani
The pathogen infects the roots and stems of seedlings from the soil, causing the diseased parts to sink and shrink, showing a dark brown color. When the seedling tissue is not lignified, it causes collapse and the seedlings fall from the ground; When seedlings have been semi-lignified or lignified, they show wilting symptoms. When wet, the disease grows white hyphae or pink mildew layer, which leads to seedling withering and death in severe cases, resulting in lack of seedlings and broken ridges Harm to apple, pear, ginkgo, begonia, peach, Berberis purpurea, grape, pear, pine, fir and other garden trees. Overwintering in the soil with hyphae or chlamydospores, wet and low temperature, the soil board is seriously ill.
Prevention and control methods:
(1) Remove the diseased plants in time and burn them centrally.
(2) Disinfect the soil, using 40% formalin with the dosage of 50ml/m2, adding water to 8 ~ 12kg, and then watering the surface, or mixing 70% pentachloronitrobenzene powder with 80% zineb wettable powder with the dosage of 8 ~ 10g/m2.
(3) Before the seedlings are unearthed, water should be properly controlled.
(4) At the initial stage of the disease, irrigate with 50% amobam 300-400 times solution or 70% thiophanate-methyl wettable powder 1000 times solution.
(3) Purple feather disease
Also known as purple root rot. The disease is widely distributed, with about 100 hosts belonging to 45 families, such as pine, fir, poplar, willow, Sophora japonica, Toona sinensis, apple, pear, peach, grape, jujube, chestnut, jujube and mulberry. The disease started from tender new roots and gradually spread to lateral roots and main roots. At the initial stage of infection, the roots first lose their original luster, then turn yellow-brown, and finally turn black and rot. There are purple reticular hyphae or hyphae bundles on the surface of injured roots, and some of them also have purple sclerotia. The cortex of the diseased root is easy to fall off from the xylem. In rainy season, hyphae can spread to the root neck or stem base, and even reach the surface of rhizosphere soil, forming a purple-red membranous hyphae layer. The pathogen overwinters with hyphae, hyphal bundles, sclerotia and biofilm on the root of the disease, and spreads the pathogen through soil, water flow and seedlings. The growth and extension of hyphae can also spread, and low-lying and humid areas or areas with poor drainage are conducive to the breeding of pathogenic bacteria.
Prevention and control methods:
(1) rotates with Gramineae at an interval of 5-6 years.
(2) Planting with good drainage and loose and breathable soil.
(3) soil disinfection, with 50% carbendazim 5 ~ 10g/m2.
(4) When it is necessary to introduce non-toxic seedlings, strict inspection shall be conducted to prevent the introduction of diseased seedlings.
(5) The seedlings can be disinfected by soaking in warm water at 45℃ for 20 ~ 30 minutes, or soaking the roots in 2% copper sulfate for 3 hours or soaking in 20% lime water for 0.5 hours. After treatment, the roots can be washed with clean water and planted.
(6) Timely treatment of diseased plants. The roots of mild plants can be cut off, the cut surface can be disinfected with Bordeaux solution, and the surrounding soil can be watered with 20% lime water or 25% ferrous sulfate. Pull out the seriously ill plants and burn them, and change the soil in the diseased areas.
(4) Root-knot nematode disease
Nematode disease The underground part is characterized by the formation of tumors of different sizes on the lateral roots and fibrous roots, which are smooth and hard, and then turn black, with milky white and shiny particles inside, that is, nematodes. It can affect the absorption of root system, make the aboveground part grow weak, make the plant shorter, turn the leaves yellow, make the flowers smaller, and even lead to the death of the plant in serious cases. It mainly harms peony, peony, rose, rose, hibiscus, jasmine, camellia, osmanthus, Erythrina, Hypericum japonicum and other garden plants. The insect overwinters in soil or diseased body as eggs, larvae and adults, and mainly spreads through soil; Disease seedlings and plants can cause long-distance transmission, and running water, immature fertilizers, tools and people can also spread diseases.
Prevention and control methods:
(1) Strengthen quarantine to prevent epidemic diseases from spreading to epidemic-free areas.
(2) carrying out soil disinfection. Available 20% dibromochloropropane 5 ~ 8g/m2; Or 20 g/m2 of 4% demerol granules; Or 3% carbofuran granules 15 ~ 20g/m2.
(3) At the onset, apply 10% aniline phosphorus, 30 ~ 45 kg per hectare.