Pine wood nematode disease is caused by a parasite called pine wood nematode, also known as pine wilt, which is a devastating disaster for the growth of pine trees. Pine wood nematode disease originated in North America, this disease and insect will make pine trees wilt, for a variety of pine tree species and some other tree species have a great harm, it has a large hazard, fast transmission speed, very difficult to control the characteristics. This disease has previously occurred in the United States, Mexico, Canada, Japan and other countries, and was introduced to China in the 1980s, causing great harm to the growth of pine trees in many parts of China.
Due to the Wenchuan "542" earthquake, there are many post-disaster recovery and reconstruction projects, frequent transportation of pine products and packaging materials, and the passage of the Beijing-Kunming Expressway, resulting in pine wood nematode diseases in ningqiang county to varying degrees, which seriously threatens the health and safe growth of the local forest ecology. Pine wood nematodes, as the main culprits of this disease, are mainly transmitted by pine brown tianniu. Pine wood nematode disease, as the disease with the greatest impact on pine trees in Ningqiang County, has destroyed many pine trees, caused great economic losses, and has posed a serious threat to the forest resources and ecological environment of Ningqiang County. Now combined with the actual work, this paper will analyze the prevention and control of pine wood nematode disease and propose corresponding measures.
<h1 class="pgc-h-arrow-right" >1 Pathogenic analysis of pine wood nematode disease</h1>
According to relevant studies, the pathogenic principle of pine wood nematodes mainly includes: pine wood nematodes will secrete a large number of cellulase, destroy the cell wall of pine tree epidermis, the water inside the pine tree can not be transported, and finally lead to the lack of water death of pine trees; according to the investigation and analysis of relevant experts, pine trees infected with pine wood nematode disease, pine wood nematodes will secrete a large number of toxic substances, these toxic substances will cause pine metabolism disorders to cause pine tree death; after trees are infected with pine wood nematode disease, Many bubbles will form in the tube cells in the tree, hindering the flow of water in the pine tree, and the pine tree will die.
The fatal point of pine wood nematodes to pine trees is mainly to destroy the water transport system of trees, so that pine trees wilt, the time of disease is fast, in a very short period of time, the water of trees will be lost, trees will wither, resulting in tree death, and the initial incidence is only concentrated in a few places or areas. Therefore, in the early stage of the disease, it is necessary to do a certain degree of defense work, focus on some diseased trees, and slow down the spread of pine wood nematode disease. Pine wood nematodes themselves are not transmissible, mainly through the medium of pine brown tianniu.
Generally occurs in May-October, pine brown cattle nibble on the young branches of pine trees, pine wood nematodes enter the pine tree body through wounds, a large number of reproduction leads to the destruction and death of resin tract parenchymal cells and epithelial cells, resin secretion is blocked or stopped, often single branches or the whole branch will appear, at the beginning the appearance of the tree looks normal, and then the leaves will gradually change color, conifers yellow-brown or reddish brown, wilted and droopy, and finally face death, the death of pine trees will also change with the time and number of pine tree insects invading. When entering the summer, after the temperature of the outside world rises, the infestation of diseases and insects will gradually increase, and the incidence will become higher and higher.
<h1 class= "pgc-h-arrow-right" >2 Control measures for pine wood nematode disease</h1>
Ningqiang County has taken many measures to control pine wood nematode disease in terms of forestry development, and to a certain extent, it has controlled the spread and spread of pine wood nematode disease, but due to the great harm and rapid spread of pine wood nematode disease, it is difficult to completely eradicate, and it is still facing problems in many aspects. In terms of prevention and control, a lot of chemical pesticides will be used, and the damage to the ecological environment is more serious, and at the same time, it is not completely in place in the prevention and control of pesticides, and it is difficult to control the epidemic.
2.1 Chemical control
The use of chemical control is mainly to eliminate the pine brown Tianniu, this chemical control is based on the environment to take different control methods, in the pine brown Tianniu adult stage, by spraying green Weer microcapsules on the pine tree or on the ground, can be immediately broken when the Tianniu touches, the release of the original drug adheres to the feet of the Tianniu and enters the body, so as to achieve the purpose of killing the Tianniu. For the control of pine wood nematodes, some powerful insecticides such as fontosophos and ethyl phosphorus will be used, which can be used at the root of pine trees, which can effectively prevent the invasion and reproduction of nematodes and make the medicinal effect play to the best.
In the winter and spring, the larvae are generally in the wood, spraying agents can not play a very good role, for some diseased trees to be completely removed, the skin of the roots of the trees removed, the diseased trees are burned, this stage is the pine brown cattle have not been feathered before the carried out, after feathering, you need to take the agent for spraying. However, the damage of strong pesticides to the soil is also more serious, and polluting the environment will hurt the growth of vegetation.
2.2 Biological control
The method of biological control is also the most widely used method at present, which is to use the interrelationship between biological species in nature to inhibit one or another type of organism with one or another type of organism, so as to reduce the population density of pests. Its biggest advantage is that it does not pollute the environment, and it is incomparable to non-biological pest control methods such as pesticides. There are many methods of biological control, such as the use of natural enemy control, in the larval stage of the tianniu, the environmental temperature of about 25 ° C on sunny days to release the swollen leg bee, the swollen leg bee in the process of transmission, will carry a large number of white zombie bacteria, these white zombie bacteria will kill the larvae of the pine brown sky cow through transmission and infection, effectively control the growth and reproduction of the pine brown sky cow.
Can also be in June and July of each year, in a large area of pine forest spraying white zombie powder, this organism can effectively reduce the reproductive rate of pine brown cattle, to a certain extent also play a role in control, but can not achieve the effect of complete eradication; but also choose to breed some tree species that can resist pests and diseases, etc., different pine varieties for pine wood nematode disease resistance is different, masson pine and torch pine resistance to the disease is the best, therefore, in the appropriate area can expand the cultivation of masson pine and torch pine, Enhances resistance to reduce the rate of transmission of pine wood nematode disease.
2.3 Other prevention and control methods
At present, the most effective way to control pine wood nematode disease is to control the occurrence and harm of vector insects to achieve the purpose of controlling pine wood nematode disease. The main measures taken: the use of APF-1 attractants to trap the pine brown tianniu and the pathogenic nematodes it carries is an effective control measure. From May to October every year, in the forest area of the epidemic point, select the place where dead pine trees are more concentrated, hang 10 per 6.67hm², and the hanging height of the trap is not less than 2m from the ground at its bottom, and it is suspended vertically in the open and well-ventilated area between the forests as much as possible.
In the forest in a triangular or grid uniform arrangement, on time to replace the core, collect the cattle, so as to reduce the density of insect population; the centralized treatment of diseased wood, all the dead pine trees with yellow and yellow disease are cut down from the roots (the height of the pile is less than 5cm), and the dead trees and branches with a diameter greater than 0 .8cm are selected nearby for centralized burning, and the pile is disposed of for drug treatment, and 2 to 4 pieces of aluminum phosphide agent are placed first. Then use 0.8mm thick plastic film to wrap the soil cover, and use the fumigation principle to kill the insect pests in the tree felling pile and eliminate the source of the disease.
<h1 class="pgc-h-arrow-right" >3 Prevention and control measures and recommendations for pine wood nematode disease</h1>
3.1 Do a good job of epidemic monitoring
In accordance with the requirements of comprehensive monitoring, accurate prediction, and timely forecasting, establish a feedback mechanism for the transmission of information on pests and insects and a responsibility system for target management, strengthen fixed-point monitoring and special investigation of insect conditions, and each village should determine a monitor, implement the responsibility to the head of the people, implement it to the plot, carry out epidemic monitoring and census work in strict accordance with the requirements, timely and accurately grasp the dynamics of the insect situation, and report in a timely manner in accordance with relevant regulations.
At the same time, it is necessary to strengthen the investigation of the causes of the spread of the epidemic, do a good job in prevention and control work in a targeted manner, take pine wood nematodes as an important monitoring object, and establish and improve the town and village monitoring and early warning system in accordance with the requirements of comprehensive monitoring and timely reporting, scientific distribution, and perennial fixed-point monitoring. The town forestry station should comprehensively analyze the insect situation report, report the epidemic situation in a timely manner, and start corresponding early warning measures, truly achieve early detection, early reporting, and early treatment of insect conditions, form a forecast and early warning network linked from top to bottom, and promote the standardization of prevention and control work. It is necessary to strengthen the quarantine inspection of the key prevention areas of pine wood nematodes, increase the supervision of relevant places such as seedlings and timber distribution centers, strengthen re-inspection, and strictly restrict the transfer of host plants and their products from the epidemic area.
3.2 Do a good job in comprehensive prevention and control
It is necessary to take multiple measures at the same time and follow the principle of "prevention first, comprehensive management".
In the early stage and peak period of pine brown cattle feathering, it is necessary to remove insect pests through some chemical agents; carry out a census of diseased and diseased trees in the spring and autumn of each year, concentrate time, manpower and material resources to seize the best time for removal, clean up and incinerate the diseased trees in a timely manner, and the operation process needs to be carried out in strict accordance with the relevant operating procedures to prevent some insect infestation omissions; planting broad-leaved tree species in logging open space, creating mixed forests, and improving the structure of the forest stand, which will effectively and long-term control the spread of pine wood nematode disease; continue to take trap traps to trap, Reduce the density of insect populations; carry out flight prevention when funds permit; carry out strict quarantine and blockade of diseased trees in forest areas, strengthen supervision and management work, resolutely prevent the outflow of diseased trees, and at the same time do a good job in centralized treatment of diseased trees.
<h1 class="pgc-h-arrow-right" >4 epilogue</h1>
The prevention and control of pine wood nematode disease is a long-term and arduous work, which requires continuous increase in scientific research investment, the use of some advanced technologies for treatment, and increase the prevention and control of pine wood nematode disease. In the early stage of the epidemic, it is necessary to do a good job in controlling the epidemic and preventing the spread of diseases and insects; in the middle stage of the epidemic, it is necessary to concentrate on treatment and prevention, through continuous improvement of various technologies, select efficient products to apply to it, and do a good job in effective protection of the epidemic area.