Pest control measures can be divided into chemical control, using chemicals such as fungicides or pesticides; Using physical energy such as light or rays, or establishing physical prevention and control barriers; Farming prevention and control to reduce harm by changing crop varieties, farming time or environment; Biological control mainly uses natural enemies. After World War II, it became easier to kill pests and diseases because of the development of pesticides mainly composed of organic synthetic agents. But at the same time, due to the increase of drug resistance and the decrease of natural enemies, pests have increased again, and previously harmless potential pests have caused harm. At the same time, these pesticides directly harm people and animals, or pesticide residues and biological concentration cause harm through the food chain. It has been realized that these problems should be comprehensively managed or controlled. That is to say, for pest control, all possible means should be used in a non-conflicting way, and the population control system of pathogens or pests should generally be maintained within the economic tolerance range. Based on the effective use of the natural control mechanism of pathogen and pest population, supplemented by various control measures, this should be aimed at reducing the density of pathogen and pest and keeping its fluctuation range in a small range. Temporary measures, such as spraying chemicals, can only be used when the density of pests exceeds the allowable level.
At the same time, unless it is a newly infected pest or a vector of human infectious diseases, it is best not to let it go extinct. According to this idea, it is important to determine the appropriate density of pathogens and pests to adapt them to the allowable critical damage value of crops. V.M.Stern et al. (1959) call this the economic hazard level (FIL), but this word is often confused with the hazard level of crops themselves, and the so-called "economic hazard level" is also easily misunderstood. Jun Yi and Keiji Tonggu (1973) suggested that the degree of crop damage specified by product yield and quality should be called "tolerable damage level" and the corresponding pathogen or pest density should be called "tolerable pest density". In addition, in a broad sense, the term "pest control" also includes the control of harmful organisms, including harmful birds and animals or weeds.
Pest control measures are divided into agricultural control, physical control, chemical control and biological control measures. At present, chemical control measures are mostly used in routine production, and pesticide application is a common method. Physical control, such as yellow backboard, black light, sweet and sour liquid lure and other agricultural control: biological control, such as rotation of main crops, scientific use of organic fertilizer, scientific management, suitable cultivation methods, mainly using natural enemies, such as Trichogramma, Aphida wasp, and the application technology of some biological fungi.
Forest pest control scheme ⅰ. Leaf-eating pests of poplar
They are mainly Poplar Moth and Popeye Moth, which have 5-6 generations every year, and both occur at the same time, with overlapping generations, starting from the early May of 10 to the early October of 10. There is a jujube-red tumor in the front and back of the body of Yang Fan boat moth larva, and its leaves are curled, so it comes out to feed at night. There is a yellow longitudinal zone on each side of the moth larva. The sarcomas in the front and back of the body are gray with short hairs on them. The leaves are gnawed away, leaving only thick veins and petioles. When the damage is light, the leaves are reticulate and nicked, which hinders the growth of poplar. When the damage is serious, the leaves are eaten up and formed. A polished rod? Poplar growth decreased. Its control method: (it should be carried out before the third instar, at the end of May and the beginning of June)
1. Trap and kill adults with black light at the peak of emergence to reduce the population density of the next generation.
2. Control with 3% hypertonic fenoxycarb 1000 times solution, imidacloprid 1000 times solution and diphacinone1000 times solution.
3. Spray or spray powder with Beauveria bassiana high spore powder and Sendebao wettable powder 15-20g per mu.
4. When the canopy density is above 0.7, 35-40g of 1.2% Bitter Smoke EC is used per mu in the forest, and the proportion of chemicals is 1 part of chemicals and 9 parts of diesel oil, which can be controlled in the morning and evening.
Second, Huyou corpse disease
Also known as gummosis, the disease mainly harms branches and stems, as well as leaves and fruits. It is a common disease of huyou after freezing injury. The disease is grayish brown, and the affected part can produce gummosis and distiller's grains smell, leading to branching, dryness and even the death of the whole tree. Its prevention and control methods:
1, twig, cut and burn.
2. The trunk and main branches shall be scraped clean with a knife and painted with Tobuzin.
3, 50% carbendazim 100 times, the same amount of Bordeaux spray.
Third, pear rust.
Also known as red star disease, it usually damages leaves and shoots, resulting in early defoliation. The lesion forms a yellow-brown bulge on the back of the leaf with 5-7 thorns. In severe cases, it can lead to the death of leaves and even seedlings. After the fruit is damaged, it not only causes deformity, but also is inedible. The disease begins in mid-May and ends in mid-July. Its prevention and control methods:
1. Cypress can't be planted within 5km around the pear orchard, because Puccinia pyrifolia is a parasitic fungus.
2. Strengthen the management of water and fertilizer, and increase the resilience of trees. Apply urea-potassium sulfate compound fertilizer 1-3 to each young tree and 0.5 kg to fruit trees, which can be applied in ditches and holes.
3. Cultivate or plant disease-resistant varieties.
4. 20% triadimefon EC is 2000-2500 times or 15% triadimefon 1500-2000 times, and it can be sprayed once every 10 day in the onset period and continuously for three times.
Four, pear aphid
Leaf damage 10 generation occurs every year, and the leaves at the top of new shoots are seriously damaged. Damaged leaves roll into corners and contract forward, and aphids lurk in them. Affect photosynthesis and hinder the growth of pear trees.
Control methods: pear bud stage, 10% imidacloprid 3000 times solution, 50% pirimicarb 2000 times solution. 5. Anti-freezing treatment and tree restoration of Huyou.
Cut off dead branches, remove dead leaves, treat the wound, and smear the wound with paint, vaseline, etc. And spray the whole plant with the same amount of Bordeaux mixture, sulfur mixture or 1000 times carbendazim to prevent disease infection. For slightly frozen trees, topdressing outside the roots with 0.3% urea and 0.2% potassium dihydrogen phosphate aqueous solution for 2-3 times. For trees with severe freezing damage, sufficient decomposed organic fertilizer should be applied, and topdressing should be thin and rich. Special attention should be paid to controlling the fertilization period to promote the control of spring and summer and autumn, which is conducive to the recovery of tree potential.
The causes of forest diseases and insect pests in China rank second in the world, and there are many kinds of forest diseases and insect pests. According to incomplete statistics, the diversity of pests and the complexity of environmental conditions have brought certain difficulties to the prevention and control work. It is particularly noteworthy that the struggle against pests and diseases is long-term and arduous. Even pests and diseases can't be controlled for a long time, which costs a lot of money and manpower every year, but there are still a large area of trees that are eaten to death. The reason is:
(1) Forest pests and diseases have the ability to spread actively or rely on natural forces, and have strong reproductive ability. Most individuals are destroyed, but the remaining individuals can spread quickly after several generations through reproduction.
(2) With the development of forestry production, the forested area has been continuously expanded, especially the growth of artificial pure forest area, and it has rebounded rapidly.
(3) The communication of forestry production activities at home and abroad provides favorable conditions for the survival of pests, and the damaged area may expand accordingly. With the increasing frequency of latent areas of seedlings, wood, scions and other materials, new pest species may continue to increase.
(4) With the change of environmental conditions, the genetic characteristics and adaptability of pests have been enhanced. Even some insect-resistant varieties are not permanent. The result of long-term adaptation is the gradual variation or decline of genetic characteristics, and it is necessary to continuously cultivate new insect-resistant varieties. It can be seen that effective pest control is a long-term, complex and arduous task.
Problems in forest pest control (1) The occurrence area of forest pests and diseases is increasing, making the control more difficult. With the increase of artificial afforestation area, especially the increase of pure forest with single tree species, the harm of pests and diseases is intensified. 1970, the occurrence area of forest pests and diseases in the whole province was1790,000 mu, 198 1 year rose to 6.75 million mu,11650,000 mu. Faced with this grim situation, our province began to implement forest defense target management in 1992, and the occurrence area decreased year by year, reaching 4.53 million mu in 1997. However, due to the continuous drought in recent years, the winter is warmer, the mortality of pests in winter is low, and the occurrence area has increased. At present, with limited funds, manpower and technology, it is more difficult to prevent and control.
(2) The types of pests and diseases caused by disasters have increased, causing serious damage and loss. At present, the number of serious pests and diseases in the province has increased from 35 in the early 1980s to about 50, some of which were introduced from other places and some of which were never found in our province. In the past, Dendrolimus punctatus, Tetranychus davidianus and Cerambycidae, which were seriously harmful, have not been well controlled, and some of them occur every year in some areas, even causing serious losses. Every year, forest diseases and insect pests reduce the output of timber by more than 700,000 cubic meters, resulting in direct economic losses of more than 200 million yuan, which has also brought immeasurable impact on ecological and social benefits.
(3) The potential threat of dangerous pests and diseases is increasing. Since the end of 1980s, many kinds of dangerous pests have invaded our province, such as American white moth, bark beetle, apple aphid, pinworm and so on. Because our province has taken effective measures to control these dangerous pests, although it has not caused great harm, the potential threat cannot be ignored. Our province is a suitable area for international quarantine pest Bursaphelenchus xylophilus and domestic quarantine object Bursaphelenchus japonicus. These two pests may invade our province at any time, especially Bursaphelenchus xylophilus. Once invaded, it is likely to destroy a large area of Pinus tabulaeformis forest in our province in a short time.
(4) Stubborn and difficult to treat, and outbreaks often occur. In the past, Dendrolimus punctatus, Dendrolimus punctatus, Pistacia chinensis, Popeye moth, Larix gmelinii and Anoplophora glabripennis were quite stubborn, most of them had the characteristics of outbreaks, and some of them broke out in local areas almost every year. If the monitoring can't keep up, pests and diseases often can't be found in time at the initial stage, and when they are found, it is already a very serious situation, which makes the prevention and control quite passive.
Take measures to prevent and control forest diseases and insect pests (1) and make predictions. Pest prediction is to detect the occurrence and development of pests by scientific methods, and to correctly infer the occurrence and development trend of pests by combining reconnaissance materials with local climate conditions and forest growth and development at that time. Prediction is an important measure to implement prevention. The organization of forecasting should take the provincial, county and municipal forestry bureaus or townships as forecasting units, set up forecasting points in nurseries and key villages, form a mass forecasting network to carry out forecasting activities, and carry out mass forecasting and prevention.
(2) Strengthen the link based on forest management. The prevention and control of afforestation is based on the overall situation of production and ecology. First, by breeding insect-resistant varieties, building mixed forests, and carrying out scientific tending management in tree species selection, suitable land and trees, afforestation methods, tending management, etc., the protective performance of trees is fundamentally improved, laying a foundation for the prevention and control of pests and diseases. However, silviculture prevention and control can not be separated from other prevention and control, nor can it rely solely on silviculture prevention and control, let alone other prevention and control. A large area of pure forest is a hotbed for the occurrence and spread of diseases and insect pests. Closing hillsides to facilitate afforestation, protecting shrub nectar plants, gradually transforming simple forests into mixed forests, transforming single-layer forests into multi-layer forests, and transforming sparse forests into dense forests, thus forming a forest system with various tree species, forest species and stand types year by year. The prevention work focuses on protection, combining protection with reproduction, establishing protected areas, improving biological communities and improving the protective performance of trees. Achieve the goal of no harm to insects. When the insect population density increases under special climatic conditions, other control measures will be temporarily supplemented in a local area.