How to plant a large-leaf boxwood hedge? Pest and disease control measures for large-leaf boxwood hedges
How to plant a large-leaf boxwood hedge? A large-leaf boxwood hedge refers to those planted densely with shrubs or small trees at close row and plant spacings, planted in single or double rows, in a tightly combined regular planting form known as a hedge. Commonly used hedge plants include boxwood, privet, red-leaf barberry, and water wax. Hedges can not only cover unsightly views and serve for isolation and protection, but also prevent dust and noise and guide visitors along viewing routes.
1. Scientific planting
When planting a large-leaf boxwood hedge, a planting trench should be dug, and the width of the planting trench should be greater than the designed width of the hedge, which is beneficial for later management. After digging the planting trench, apply base fertilizer in time, and well-rotted and fermented cattle and horse manure is best for the base fertilizer. When selecting seedlings, choose seedlings free of pests and diseases. When planting, first plant the outer seedlings, and at the same time require that the row and plant spacings remain basically consistent. When planting a hedge of 3 rows or more, make the plants cross in a triangular arrangement, which is beneficial for ventilation and light penetration of the hedge. After planting, press the soil firm around each plant one by one, and at the same time require that the planting height be basically consistent. After planting, prune in time, which not only helps make the hedge neat and uniform, but can also reduce the transpiration of the plants and improve the survival rate of the plants.
2. Proper water and fertilizer
Water and fertilizer management is an important part of maintaining a large-leaf boxwood hedge. Because the root system of large-leaf boxwood is relatively shallow, its own drought resistance and waterlogging resistance are not strong. During daily maintenance, determine whether to water or how much to water according to rainfall conditions. In the rainy season, drain accumulated water in time to prevent root rot caused by excessive water. After the base fertilizer is applied to a large-leaf boxwood hedge, apply nitrogen fertilizer once each year after pruning in late spring and early summer, and apply a phosphorus-potassium compound fertilizer once after autumn begins.
3. Reasonable pruning
Pruning of hedges is the top priority of maintenance work. Hedge shapes include regular and irregular types. Common regular types include rectangular or Great Wall crenellation shapes, and irregular shapes include wave shapes, etc. The specific choice can be determined according to actual conditions, but it should be noted that when pruning, the top and both the inner and outer sides must be cut flat, which can prevent the lower branches and leaves of the hedge from becoming bare. The shaping and pruning of a large-leaf boxwood hedge generally has two time periods: one is late spring and early summer, and the other is around mid-autumn. Pruning in late spring and early summer allows wounds to heal quickly and can reduce the occurrence of pests and diseases. Pruning around mid-autumn allows wounds to heal in time, and at the same time will not sprout too many branches, which is beneficial for the plants to overwinter safely.
4. Pest and disease control
Large-leaf boxwood hedges are planted relatively densely, so pests and diseases are likely to occur. Common pests and diseases of large-leaf boxwood hedges include powdery mildew, sooty mold, powdery mildew, red spider mite, cotton aphid, Japanese wax scale, Euonymus gold-banded geometer moth, Euonymus arrowhead scale, brown-edged green nettle caterpillar, etc., and targeted control can be carried out according to the damage situation. At the same time, when planting, do a good job in seedling quarantine, disinfect the soil, strengthen seedling pruning, do a good job in water and fertilizer management, and especially pay attention to the application of phosphorus and potassium fertilizers to enhance the disease resistance of the plants.
Pest and disease control techniques for large-leaf boxwood
Large-leaf boxwood is currently an excellent evergreen broadleaf tree species for urban landscaping and improving the ecological environment in northern China. The number planted has exceeded 1 billion plants. Its stress resistance and ornamental value are outstanding, and it can maintain glossy emerald green leaf color in winter. It is often planted mainly in the forms of hedges, large color-block shapes, and specimen planting.
In recent years, because quarantine and treatment of pests and diseases have been neglected in the exchange of seedlings between regions, the area affected by pests and diseases has expanded year by year. Some pests and diseases have developed into disasters due to untimely control, affecting growth and ornamental value in mild cases and causing plant death in severe cases. During cultivation, the common pests and diseases include the following:
1. Large-leaf boxwood powdery mildew. It mainly damages the leaves of large-leaf boxwood, and when severe, it can also infect new shoots. The pathogen produces a gray membranous fungal layer in late autumn and winter to overwinter. In early April of the following year, when the temperature is above 18°C and the relative air humidity is 70-85%, that is, during the leaf expansion period of new shoots of large-leaf boxwood, the pathogen on old leaves produces a large number of conidia, which spread by wind to new leaves and germinate on them, produce germ tubes, and finally invade the tissue. Newly infected new leaves first fade green and produce yellow spots, then many small round spots are scattered on the leaves. As the disease worsens, the spots gradually expand and heal with each other, becoming irregular large spots. Because this fungus parasitizes on the surface of host branches and leaves and produces haustoria that penetrate deep into epidermal cells to absorb nutrients, after new leaves are infected, symptoms of wilting and water loss often appear, the leaves become thinner and wrinkled, and diseased shoots become distorted and shrunken.
Control methods: (1) Prune appropriately to enhance permeability. (2) In the early stage of disease occurrence, alternately spray 25% triadimefon 1300x solution, 70% thiophanate-methyl 700x solution, and 50% Tuzet wettable powder 800x solution. If the disease is severe, pruning must be carried out, removing diseased leaves and burning them in a centralized manner, and then spraying pesticides for control.
2. Large-leaf boxwood brown spot disease. It overwinters in the diseased spots as mycelium and stroma. In late May each year, when the temperature rises to about 25°C, the stroma in old diseased spots produces conidia and begins primary infection. It generally infects lower old leaves first. After old leaves are infected, brown-green small spots initially appear on the leaves, gradually turn yellow and then brown. The spots are nearly round or irregular and can connect into patches. The center is grayish white, and the edge has a light brown slightly raised ring pattern. Dense small black dots grow on the spots. Once conditions are suitable, reinfection continues. Early June to mid-July is the peak period of disease expansion, and after October it enters dormancy.
Control methods: (1) Select healthy disease-free seedlings for planting. (2) From early June to July, spray 50% carbendazim 500x solution or 75% chlorothalonil 500x solution, or 50% Tuzet wettable powder 800-****x solution for prevention to reduce the incidence rate, once every 10-15 days, for 3 consecutive sprays. (3) In winter, remove fallen leaves and burn them in a centralized manner.
3. Aphids. Wingless parthenogenetic female aphids and nymphs gather on branch tips and the undersides of tender leaves to suck sap and cause damage. Damaged leaves often have white waxy secretions, which easily cause sooty mold. When severe, branches and leaves turn black, affecting plant growth and ornamental value. Generally, about 10 generations occur per year.
Control methods: (1) Protect natural enemies such as ladybugs and large green lacewings. (2) Chemical control: spray 20% chrysanthemum-kill emulsifiable concentrate 2000x solution or 2000-3000x imidacloprid powder.
4. Japanese wax scale. One generation occurs per year, overwintering as fertilized female adults on branches and trunks. Mid-June to early July is the peak hatching period.
Morphological characteristics: Female adult, wax shell grayish white or slightly flesh-red, oval. Male adult, body dark brown or brown, head and thoracic tergites darker. Nymph, wax shell oval to elliptical, back slightly raised.
Control methods: (1) Quarantine control. When purchasing seedlings from other places, plant quarantine procedures must be strictly implemented to prevent artificial spread of pests. (2) Strengthen garden maintenance and management. Through maintenance and management, create environmental conditions unsuitable for scale insects to survive. Implement crop rotation, clean the garden in time, and burn fallen leaves, weeds, pest- and disease-damaged branches, etc. in a centralized manner to reduce the overwintering pest population base. Fertilize reasonably to enhance plant resistance. Prune reasonably to increase ventilation and light penetration, change the living environment of scale pests, weaken their reproductive capacity, and reduce damage. (3) Chemical control. When insect population density is not high, use a soft brush dipped in a small amount of dichlorvos diluted with water (1:50-100 solution) to wipe them out, or remove damaged branches and burn them in a centralized manner. During the peak nymph period, spray 40% omethoate 1000x solution or deltamethrin 2500x solution, once about every 10 days, for 3 consecutive sprays. (4) Protect natural enemies such as parasitic wasps.
5. Large-leaf boxwood geometer moth. Three generations occur per year, overwintering as pupae in the layer of dead branches and fallen leaves on the soil surface. Overwintering-generation adults begin to emerge in early April, with mid-month as the peak emergence period. They lay eggs 1-2 days after emergence, with mid-April as the peak egg-laying period, and the egg stage lasts 6-7 days. First-generation larvae cause damage from late April to mid-May, second-generation larvae appear from mid-June to early July, and the third generation is from early August to early October. A few larvae enter the soil to overwinter in early September. During the year, damage is most severe from late April to mid-May and in late August. After hatching, the larvae gather on the undersides of host leaves within 3-4 hours and scrape and feed on the leaf mesophyll. After the 3rd instar, they disperse to feed on leaves. When insect population density is high, a single tree can have as many as 30-50 larvae. When food is scarce, leaf stalks and the cortex of new shoots are also gnawed, seriously affecting tree vigor growth and even causing tree death.
Control methods: (1) Use the phototaxis of adults to carry out light trapping and killing during the adult period. (2) During the larval damage period, spray 50% fenitrothion emulsifiable concentrate 500x solution or 4.5% beta-cypermethrin 2000x solution. (3) Remove egg masses during the egg-laying period. In winter, plow the soil around the roots to kill overwintering pupae.
(471900 Yanshi City Forestry Bureau, Henan Province, Shi Xiaofeng, Wei Xuefeng, Yang Xiaoyan
Pest and disease control techniques for large-leaf boxwood
Large-leaf boxwood is currently an excellent evergreen broadleaf tree species for urban landscaping and improving the ecological environment in northern China. The number planted has exceeded 1 billion plants. Its stress resistance and ornamental value are outstanding, and it can maintain glossy emerald green leaf color in winter. It is often planted mainly in the forms of hedges, large color-block shapes, and specimen planting.
In recent years, because quarantine and treatment of pests and diseases have been neglected in the exchange of seedlings between regions, the area affected by pests and diseases has expanded year by year. Some pests and diseases have developed into disasters due to untimely control, affecting growth and ornamental value in mild cases and causing plant death in severe cases. During cultivation, the common pests and diseases include the following:
1. Large-leaf boxwood powdery mildew. It mainly damages the leaves of large-leaf boxwood, and when severe, it can also infect new shoots. The pathogen produces a gray membranous fungal layer in late autumn and winter to overwinter. In early April of the following year, when the temperature is above 18°C and the relative air humidity is 70-85%, that is, during the leaf expansion period of new shoots of large-leaf boxwood, the pathogen on old leaves produces a large number of conidia, which spread by wind to new leaves and germinate on them, produce germ tubes, and finally invade the tissue. Newly infected new leaves first fade green and produce yellow spots, then many small round spots are scattered on the leaves. As the disease worsens, the spots gradually expand and heal with each other, becoming irregular large spots. Because this fungus parasitizes on the surface of host branches and leaves and produces haustoria that penetrate deep into epidermal cells to absorb nutrients, after new leaves are infected, symptoms of wilting and water loss often appear, the leaves become thinner and wrinkled, and diseased shoots become distorted and shrunken
Control methods: (1) Prune appropriately to enhance permeability. (2) In the early stage of disease occurrence, alternately spray 25% triadimefon 1300x solution, 70% thiophanate-methyl 700x solution, and 50% Tuzet wettable powder 800x solution. If the disease is severe, pruning must be carried out, removing diseased leaves and burning them in a centralized manner, and then spraying pesticides for control.
2. Large-leaf boxwood brown spot disease. It overwinters in the diseased spots as mycelium and stroma. In late May each year, when the temperature rises to about 25°C, the stroma in old diseased spots produces conidia and begins primary infection. It generally infects lower old leaves first. After old leaves are infected, brown-green small spots initially appear on the leaves, gradually turn yellow and then brown. The spots are nearly round or irregular and can connect into patches. The center is grayish white, and the edge has a light brown slightly raised ring pattern. Dense small black dots grow on the spots. Once conditions are suitable, reinfection continues. Early June to mid-July is the peak period of disease expansion, and after October it enters dormancy.
Control methods: (1) Select healthy disease-free seedlings for planting. (2) From early June to July, spray 50% carbendazim 500x solution or 75% chlorothalonil 500x solution, or 50% Tuzet wettable powder 800-****x solution for prevention to reduce the incidence rate, once every 10-15 days, for 3 consecutive sprays. (3) In winter, remove fallen leaves and burn them in a centralized manner.
3. Aphids. Wingless parthenogenetic female aphids and nymphs gather on branch tips and the undersides of tender leaves to suck sap and cause damage. Damaged leaves often have white waxy secretions, which easily cause sooty mold. When severe, branches and leaves turn black, affecting plant growth and ornamental value. Generally, about 10 generations occur per year.
Control methods: (1) Protect natural enemies such as ladybugs and large green lacewings. (2) Chemical control: spray 20% chrysanthemum-kill emulsifiable concentrate 2000x solution or 2000-3000x imidacloprid powder.
4. Japanese wax scale. One generation occurs per year, overwintering as fertilized female adults on branches and trunks. Mid-June to early July is the peak hatching period.
Morphological characteristics: Female adult, wax shell grayish white or slightly flesh-red, oval. Male adult, body dark brown or brown, head and thoracic tergites darker. Nymph, wax shell oval to elliptical, back slightly raised.
Control methods: (1) Quarantine control. When purchasing seedlings from other places, plant quarantine procedures must be strictly implemented to prevent artificial spread of pests. (2) Strengthen garden maintenance and management. Through maintenance and management, create environmental conditions unsuitable for scale insects to survive. Implement crop rotation, clean the garden in time, and burn fallen leaves, weeds, pest- and disease-damaged branches, etc. in a centralized manner to reduce the overwintering pest population base. Fertilize reasonably to enhance plant resistance. Prune reasonably to increase ventilation and light penetration, change the living environment of scale pests, weaken their reproductive capacity, and reduce damage. (3) Chemical control. When insect population density is not high, use a soft brush dipped in a small amount of dichlorvos diluted with water (1:50-100 solution) to wipe them out, or remove damaged branches and burn them in a centralized manner. During the peak nymph period, spray 40% omethoate 1000x solution or deltamethrin 2500x solution, once about every 10 days, for 3 consecutive sprays. (4) Protect natural enemies such as parasitic wasps.
5. Large-leaf boxwood geometer moth. Three generations occur per year, overwintering as pupae in the layer of dead branches and fallen leaves on the soil surface. Overwintering-generation adults begin to emerge in early April, with mid-month as the peak emergence period. They lay eggs 1-2 days after emergence, with mid-April as the peak egg-laying period, and the egg stage lasts 6-7 days. First-generation larvae cause damage from late April to mid-May, second-generation larvae appear from mid-June to early July, and the third generation is from early August to early October. A few larvae enter the soil to overwinter in early September. During the year, damage is most severe from late April to mid-May and in late August. After hatching, the larvae gather on the undersides of host leaves within 3-4 hours and scrape and feed on the leaf mesophyll. After the 3rd instar, they disperse to feed on leaves. When insect population density is high, a single tree can have as many as 30-50 larvae. When food is scarce, leaf stalks and the cortex of new shoots are also gnawed, seriously affecting tree vigor growth and even causing tree death.
Control methods: (1) Use the phototaxis of adults to carry out light trapping and killing during the adult period. (2) During the larval damage period, spray 50% fenitrothion emulsifiable concentrate 500x solution or 4.5% beta-cypermethrin 2000x solution. (3) Remove egg masses during the egg-laying period. In winter, plow the soil around the roots to kill overwintering pupae.