Management and Control of Garden Plant Diseases and insect pests in North China

As urban garden plants need to comprehensively consider the ornamental needs, the introduction of garden plants among areas will increase the risk of diseases and insect pests, coupled with the imperfect framework of the relevant work system, it is difficult to implement the quarantine work, thus missing the best practice of prevention and control, or there are many deficiencies in the prevention and control of garden plant diseases and insect pests, so it is difficult to control garden plant diseases and insect pests.

1 effectively improve the quality of disease and insect pest control of garden plants in North China

Based on the full analysis of the current situation of garden plant pest control in northern China, the relevant staff, through the specific analysis of specific problems, improve the quality of pest control work from all aspects.

(2) reasonable landscape design

Reasonable landscape design is an important means to achieve pest control and isolation. To know that the introduction of various plants will bring a variety of threats of diseases and insect pests will bring additional risks to garden plants, so when designing gardens, we should fully consider the risks of diseases and insect pests faced by different plants, reasonable planning, through staggered planting, to better achieve the control of diseases and insect pests, which is also an important factor that must be taken into account in landscape design. Take the urban environment for example, the combination of trees and shrubs will form a scattered compound plant community, which has a positive limiting effect on diseases and insect pests.

(3) pay attention to the construction of species diversification and the interaction between them.

The environment in the northern region is dry and cold, coupled with the unstable ecosystem of the garden environment itself, which is easy to cause the occurrence of diseases and insect pests, but if the plant varieties are diversified, if there are great differences among species, there is often mutual inhibition of diseases and insect pests, which is conducive to the control of diseases and insect pests in the whole plant community. However, some plants growing together often cause diseases and insect pests, which should be noted. For example, pear and cypress planting together will cause pear juniper rust, pine trees and peony planting together will cause pine peony rust, and so on.

(4) strengthen the construction of prevention and control system.

The prevention and control system of plant diseases and insect pests is a whole, and comprehensive construction should be realized to avoid the occurrence of deficiency. In addition to improving the professional quality of relevant staff, attention to climate conditions should also be an important part of pest control work. Caution should be taken in the use of physical control, chemical control and biological control.

Forecast of Garden Plant Diseases and insect pests in North China in July

July is the season of high temperature and humidity, and it is one of the key periods for pest control. 1. Forecast of garden plant pests (1) A variety of beetles and grubs in June have been feathered into adults, and many green plants such as hibiscus, beech, tung, bayberry, firethorn, and red maple have been seriously harmed by beetles, resulting in more holes in their leaves. From late July to early August, grubs will hatch into the surface soil under the tree to harm the lawn root, if the population is large, it may cause the death of the whole lawn. (2) the harmful period of rhododendron bug is from April to October, and the outbreak may be caused by high temperature drying in July and August. (3) the red spiders on the red spider roses are easy to break out in the cool season in May, but the red spiders on camphor are different, easy to break out in the season of high temperature and dryness, and the lack of rain in the plum season will cause the occurrence of red spiders in camphor. After feeding, the red spider causes the leaves to lose green and brown, which affects not only the tree potential but also the landscape. (4) the diamondback moth is commonly known as sheep spicy hair, and there are many species, such as yellow thorn moth, green thorn moth, green thorn moth, flat thorn moth and so on. Most of the larvae overwintered in the cocoon, and the young fine larvae ate leaves in clusters, which caused a wide range of damage, harming many kinds of garden plants, such as maple poplar, red leaf plum, camphor, heather, cherry blossoms and so on. When it is serious, it can eat up the leaves and have a great impact on the landscape. It generally appears in the middle and late June, and it is the heaviest from July to September. Therefore, attention should be paid to the full spraying of the leaf back during spraying control. (5) Spodoptera litura is dominated by Spodoptera litura and Spodoptera litura, which has occurred in June. The high temperature after the plum season may cause the outbreak of Spodoptera litura, so we should pay close attention to the occurrence of Spodoptera litura. Once bald spots are found on the lawn, we should focus on observation and timely prevention and control if found. Because of its habit of sleeping during the day and going out at night, the time of prevention and control must be chosen after the sun goes down. (6) armyworm is mainly harmful to lawn. This insect has a large amount of food and causes damage quickly. if it is not controlled in time, it can eat up the leaves of lawn grass in one night. Bt emulsion, thiazuron No. 1 or thiazuron No. 3 should be used to control the initial stage of larvae. (7) Kang's pink scale, also known as mulberry pink scale. At present, there is a large area of occurrence on the road isolation zone in the urban area and on the golden leaf privet in the community, and the symptoms are often mistaken for the drying of leaves caused by lack of water in the sun. Careful observation shows that white flocs are produced, and the relevant units should pay enough attention to the prevention and control. (8) in addition to the above-mentioned major diseases and insect pests, attention should also be paid to the control of Plutella xylostella (pyrethroids and BT); coir moth (diflubenzuron 3); willow blue leaf beetle (BT) on willow trees; camphor nest borer on some camphor (spraying with BT 500x, mirax 3 2000 times or bitter tobacco EC 800x) The leafhopper on the warm-season lawn (dog tooth root, paradise grass, etc.), the yellow poplar silk wild borer on the melon seed and yellow poplar, etc. 2. Main diseases (1) Leaf spot of Ligustrum lucidum: there are nearly round brown spots on the diseased leaves, often with wheel lines, and the periphery of the edge is often yellow. In the initial stage, the lesion is smaller, and the diameter of the expanded spot is more than 1 cm. The diseased leaves are very easy to fall off from the branches, resulting in the phenomenon of baldness in the branches of Ligustrum lucidum in the seriously affected area. The first occurrence period is in the first ten days of April, and the peak period is from July to August and October. (2) Albizia wilt: at the initial stage, the leaves were yellow, wilted and drooping, and then dried up and fallen leaves. In summer, the branches become rough and sometimes produce small black particles. When serious, yellow leaves, withered branches and bark rot, resulting in the death of the whole plant. (3) powdery mildew: there are mainly poplar powdery mildew, big leaf yellow poplar powdery mildew, crape myrtle powdery mildew and so on.

Control methods of garden plant diseases and insect pests

(1) Seedling quarantine

The distribution range of some diseases and insect pests is narrow, causing serious damage only in local areas. However, these diseases and insect pests can spread to the new area with the long-distance transportation of seedlings' seeds, cuttings or roots used as breeding materials, logs and other garden products, and expand the scope of their harm. With the development of society, international or regional personnel exchanges and product exchanges have become increasingly frequent, increasing the opportunities for the spread of dangerous diseases and insect pests. For example, the American white moth was introduced into Liaoning Province from abroad, and then spread to Wugong County, Shaanxi Province with railway transportation, and into Rongcheng County, Shandong Province along with the waterway. Therefore, it is necessary to strictly implement China's quarantine laws and regulations, do a good job in the import and export quarantine of seedling diseases and insect pests at the import and export portals of airports, ports, stations, and other commodities, and do a good job in the quarantine, transportation and quarantine of seedling producing areas in China, so as to take precautions against them, it is an important measure to control the spread of dangerous diseases and insect pests.

The Ministry of Forestry of China identified 35 new domestic forest plant quarantine objects in 1996. They are Japanese pine dry scale, pear round scale, wetland pine powder scale, pine scale, larch seed wasp, nevus wasp, willow flat moth, double-hook different-winged beetle, yellow spot longicorn beetle, rust-colored longicorn beetle, double-fir longicorn beetle, American white moth, poplar dry-winged moth, poplar dry beak elephant, apple cotton aphid, apple bark moth, jujube ball scale, almond wasp, pine wood nematode, pine rust, pine needle red spot, pine needle brown spot, crown gall disease, Poplar mosaic virus disease, larch shoot blight, bamboo shoot blight, Chinese fir topping disease, eucalyptus scorch blight, kiwifruit canker, cinnamon branch blight, chestnut blight, carnation wilt, chrysanthemum leaf blight nematode, citrus canker and so on. If quarantine objects are found in the inspection, measures such as disinfection, local burning or isolation and trial planting shall be taken in time. Due to the problems of lax law enforcement and backward testing methods and facilities in quarantine work, quarantine pests such as pine wood nematode disease, American white moth, Japanese pine stem scale, pine scale and poplar stem weevil are still spreading, which should be paid great attention to by the relevant departments.

(2) Horticultural techniques

Horticultural measures are the fundamental measures to control diseases, pests and rodents, which should run through the whole production process. The main measures are:

1. Select and popularize excellent tree species with strong resistance to diseases and insect pests. There were differences in resistance to various diseases and insect pests among different tree species and among different varieties of the same tree species. If a variety only has the characteristics of fast growth and high yield, but not resistant to diseases and insect pests, it is difficult to be popularized in production. For example, Daguan poplar, which was planted in a large area in China in the 1970s, was eliminated soon because it was harmed by stem borer such as Anoplophora glabripennis. This lesson illustrates the importance of disease and insect resistance breeding in prevention and control. The work of resistance breeding in China started relatively late. Job protection workers and breeders should strengthen cooperation to select more excellent varieties with resistance to diseases and insect pests to meet the needs of production. At present, some excellent varieties or clones resistant to pine blister rust, poplar longicorn beetle, poplar canker and paulownia witches' broom have been selected.

Taking advantage of the strong genetic plasticity of poplar, some countries in Europe and America have cultivated many excellent varieties with strong resistance to diseases and insect pests. In 1988, American scientists made a breakthrough in poplar insect resistance breeding by using genetic engineering methods. Through gene chimerism, they transferred the insect-inhibiting protein gene from potato to poplar through E. coli, and developed a new type of insect-resistant tree species. Breeders in China are also carrying out research in this area.

two。 Different tree species and densities were selected according to different site conditions.

3. Build a mixed forest to avoid the simplification of tree species.

4. Afforestation with strong seedlings free of diseases and insect pests.

5. Measures such as ploughing, weeding, fertilization, irrigation and pruning should be taken to strengthen the management of middle and young forests and promote plant growth.

6. Remove diseases and insect pests from the system in time and improve sanitary conditions.

7. Indiscriminate felling is strictly prohibited to promote the growth of multi-level vegetation.

Through the above measures, the plant growth is robust, the ability of resistance to diseases and insect pests is enhanced, and all kinds of natural enemies such as insects, beneficial microorganisms and birds are obviously increased, thus the control ability of the whole plant system to diseases and insect pests is improved. The improvement of horticultural environmental hygiene conditions reduced the population of pathogens and pests.

(3) Biological control

The use of beneficial organisms to control garden diseases and insect pests has the advantages of saving energy, low control cost, no environmental pollution, long-lasting control effect and so on. In the past ten years, biological control has been paid more and more attention and should be vigorously advocated.

1. Microbial preparation. Microbial insecticides mainly include Beauveria bassiana, Bacillus thuringiensis, insect virus and so on. Beauveria bassiana is used to control Dendrolimus punctatus every year in China. From 1984 to 1986, cyanobacteria No. 6 was applied to control Pinus massoniana in Hubei, Hunan and Guangdong provinces, with an effect of more than 90%. Since 1980s, spring inchworm polyhedrosis virus, Dendrolimus punctatus cytoplasmic polyhedrosis virus and diamondback moth nuclear polyhedrosis virus have been used to control spring inchworm, Dendrolimus punctatus and Dendrolimus punctatus, respectively. The promotion area is above 6000hm2. Obvious results were also obtained by using Cladosporium to control poplar stem weevil and Taishan No.1 nematode to control poplar beetles. The output and application area of microbial preparations in China, especially Beauveria bassiana, are in the forefront of the world. However, because most of the microbial preparations are produced by local method, there is no unified quality testing standard in the country, and the quality of the preparation is not guaranteed, so there are some problems such as unstable effect and high cost in the process of application. as a result, the application area of Beauveria bassiana in some provinces has declined year by year in recent years, and the application area of Bacillus thuringiensis is not large.

Countries such as the former Soviet Union, the United States and Canada have produced a variety of registered commercial microbial preparations. The biological control area of the former Soviet Union accounts for more than 50% of the total area of forest pest control in the country every year. They mainly use Bacillus thuringiensis and polyhedrosis virus to control leaf-eating pests such as gypsy moth, oak green roll moth, pine inchworm and pine caterpillar. Beauveria bassiana is used to control bark beetles. The area of using Bacillus thuringiensis to control spruce roll moth in the United States and Canada is about 105hm2 every year. Japanese Dendrolimus punctatus cytoplasmic polyhedrosis virus (CPV) is the first registered and commercially produced virus preparation in the world to control Dendrolimus punctatus. The United States and Canada also produce a variety of viral preparations for the control of leaf-eating pests. Due to the slow effect of virus preparation, the death of insect pests can be accelerated by adding a small amount of chemical pesticides to improve the control effect.

In the United States, Australia and other countries, microbial commercial preparations have been used to control root cancer and root rot. Powdery mildew can be controlled by powdery mildew parasites, development of rust can be controlled by parasites of rust, and silver white rot of pine can be controlled by Alternaria megasporium.

2. Natural enemy insects. The parasitic natural enemies widely used in China are Trichogramma, swollen-legged wasps, wasps, aphids and longicorn beetles, while the predatory natural enemies are Mongolian ladybugs, discolored lady beetles and? Bugs, etc. From the late 1970s to the early 1980s, Trichogramma was used to control pine caterpillars in an area of hundreds of thousands of hectares. After years of production practice, it has been proved that artificial release of Trichogramma in a certain range is still a good method to control Dendrolimus punctatus under the condition of low population density. At present, it has a large application area in Zhejiang, Hunan and other provinces. Mongolian light lady beetle was used to control pine scale, parasitic natural enemy Puman was used to control concealed pests (such as Coleoptera longicorn beetles (Monochamus alternatus), bark beetles (Cypress bark beetle), Dendroctonus (Dendroctonus), gibberellins and Lepidoptera pests such as pine tip borer, six-star black spot beetle moth), swollen-legged wasps were used to control double-fir longicorn beetles, thick-sheathed longicorn beetles, green poplar longicorn beetles, and Zhou's wasps were used to control American white moths. It is effective to use APHIS gossypii to control pine scale and longicorn beetle to control green poplar longicorn beetles. However, with the exception of Trichogramma, other natural enemies have not been widely used in production because they have not completely solved the problems of breeding host, industrial production process or unstable control effect. In addition to artificial release, attention should be paid to protecting the ecological environment of the plantation in production so as to create conditions for the reproduction of natural enemies, so as to improve the control effect of various natural enemies on pests.

The United States pays great attention to the introduction of natural enemies from abroad, and the introduction of natural enemies to control larch sheath moths and other pests has been successful. France is in the forefront of the world in the study of Trichogramma. The Onleb Biological Control Experimental Station in the country collects Trichogramma from countries around the world, conducts various studies, and is used to control agricultural pests. Trichogramma was also used to control spruce roll moth in the United States, Britain, the former Soviet Union and other countries, but it was not widely used in production because the control effect was not obvious.

3. Beneficial birds. The use of artificial nests in poplar plantations to attract beneficial birds such as tits, woodpeckers and grey birds can significantly reduce the density of leaf-eating pests and stem-borer pests. It is observed that a pair of woodpeckers can control the bare-shouldered longicorn beetles in the 20~30hm2 poplar forest. Owls also have obvious control effect on forest rats.

Germany, the former Soviet Union and other countries attach great importance to the protection of beneficial birds in plantation and the research on the technology of artificially attracting beneficial birds. Because of the good ecological environment of forest in these countries, the role of beneficial birds in protecting forest is very obvious.

4. The application of extra-sexual hormones. Since the 1970s, synthetic sex pheromones have been used in the prediction and control of some pests. The traps made by Populus tomentosa sex pheromone and gypsy moth pheromone have achieved good results in killing Populus tomentosa and Plutella xylostella in China.

(4) Chemical control

At present, chemical control is still the main measure to control the occurrence of diseases and insect pests and eliminate the source of insect pests. The area of chemical control in China accounts for about 70% of the total area of forest disease and pest control. On the premise of doing a good job in forecasting and forecasting, good control results can be achieved by using pesticides in a timely manner. The insecticides commonly used in China are alfudine, imidacloprid, fipronil, carbendazim, carbendazim, trimethoprim, thiophanate, etc. The main application methods are spraying, powder spraying, fumigation, seed dressing, smoking and so on. In recent years, the application of aircraft ultra-low capacity spray control technology has improved the control effect, saved labor and reduced the cost. In the production, simple and easy application methods have also been developed, such as coating rings with poison pens on tree trunks, binding poison ropes or paper straps, inserting poison labels or tablets into wormholes, injecting liquid, spreading poison soil or bait, and so on, which have achieved good control effects. Pesticides with low toxicity, such as chlordimeform, benzoate, topazine, deltamethrin and so on, are imported. Due to the high drug price and the rising cost of aircraft control, the range of the ground spray sprayer is not enough, which affects the control effect. In some places, deltamethrin has been used alone for a long time, resulting in the emergence of drug resistance of pests, affecting the progress of chemical control work. It is worth mentioning that bamboo locusts which have been extinguished with BHC powder in the 1950s and 1960s rose in the 1980s. One of the important reasons is that no chemical agent has been found to replace BHC at present.

Fungicides can be divided into eradication agents, protective agents and internal absorbents. Eradication agents can directly kill pathogens, such as pentachlorophenol, formaldehyde and so on. Protective agents can be applied directly to plants to protect plants from damage, such as low concentration of stone sulfur mixture, Bordeaux solution, organic sulfur, organophosphorus, organochlorine and so on. Internal inhalers refer to drugs that are inhaled by plants to inhibit the spread of pathogens, such as topiramate, carbendazim, benzoate and so on. The use of chemicals includes soil disinfection, seed disinfection and plant spraying.

However, a large number of chemical control agents have produced serious "3R" problems, that is, drug resistance (Resistance), resurgence (Resurgence) and residue (Residue). Many pests have developed dozens or even hundreds of times resistance to chemical pesticides. The number of some major pests fell sharply and then suddenly rebounded to cause greater harm, and secondary pests broke out suddenly after the natural enemies were killed. Pesticides not only affect non-target species such as natural enemies, pollinating insects and wild animals, but also seriously pollute soil, water, atmosphere and animal and plant products, which in turn cause new pest crises.

(5) physical prevention and control

In production, the tendency of adults of some pests to light can be used to set up black lights or high-pressure anti-pest lamps to trap and kill adults. The seeds and cuttings can also be treated by ultrasonic, heat treatment and X-ray irradiation to eliminate pathogens or pests. For example, the paulownia witches' branch disease can be controlled by soaking the roots of paulownia seeds in warm water for 1 hour. According to the overwintering habit of Dendrolimus punctatus in northern China, plastic tape is put on the trunk before the Dendrolimus punctatus goes up the tree in spring, which can prevent the overwintering larvae from climbing the tree and reduce its harm.