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(B) Investigation Method for the Spore Dispersal Period
In a designated standard area, five sampling points were established using the 5-point sampling method. From June to July, slides were placed on the litter layer (for leaf disease) or the canopy of the sample plants (for blight disease). Vaseline was applied to the slides, which were replaced every two days and then brought back to the laboratory. Under a 400x microscope, the middle parts of each slide were observed, and spore counts were recorded using a counter. A micrometer was used to measure the field of view area, allowing the calculation of the number of spores captured per square centimeter. The period when spores were first detected is considered the beginning stage. As the spore count increases, it marks the peak period, and when the spore count reaches its maximum, it indicates the peak. When spore numbers significantly decrease, it signals the end of the dispersal period. The final stage is reached when no more spores can be captured.
(III) Prediction Methods
1. Forecasting the Occurrence Period
Based on the actual survey of the pathogenic spores' dispersal period, an effective investigation method was adopted to issue appropriate prevention and control forecasts when spore dispersal reached its peak. For example, in cases of larch early defoliation, if the number of spores captured per square centimeter exceeds 100, a suitable control forecast is issued.
2. Methods for Forecasting the Amount of Disease
(1) Statistical Method: This approach uses statistical principles to identify the internal relationship between environmental factors and disease occurrence by analyzing historical data. Based on current environmental conditions, this method predicts future disease occurrences. For instance:
1. Larch Early Deciduous Disease Prediction
Y = 68.31 - 1.68X1 - 0.5638X2 + 0.36X3
Where:
- Y: Predicted disease index for the current year
- X1: Average temperature in April and May of that year
- X2: Average relative humidity in June and July of that year
- X3: Precipitation in June and July of that year
2. Larch Litter Blight Prediction
When the average temperature, relative humidity, and precipitation in April and May are not lower than the local annual average, and the average temperature in June and July is above 17°C, relative humidity above 80%, and precipitation above 200mm, it is predicted that the disease will be severe. If the four meteorological factors in April and May are not lower than the general years, and the relative humidity in June and July is between 70% and 80%, the incidence is expected to be moderate. If the three meteorological factors in April and May are lower than the normal years, and the relative humidity in June and July is below 70%, the forecast suggests a mild outbreak.
(2) Experimental Method: This involves predicting diseases through ecological, biological, and physiological methods, such as forecasting in nurseries, systematic investigations, spore capture, and artificial cultivation.
Section II: Major Pests of Larix principis-rupprechtii
In the animal kingdom, insects cause the most serious damage to trees and seedlings. They are also the largest group in the animal kingdom, with over one million species recorded globally. Most of them feed on the roots, stems, leaves, flowers, fruits, and seeds of plants, making the majority of them pests. Forest pests have a significant impact on forest growth and development. Larch caterpillars and L. gmelinii can reduce the growth of forest trees when the damage is severe, and in recent years, some forest trees have stopped growing or even died.
The prevention and control of pests affecting Larix principis-rupprechtii should follow the principle of "prevention first, comprehensive prevention and control." It should be based on the overall concept of biology and the environment, guided by the principles of safety, efficiency, economy, and simplicity. Use forestry technology, chemical, biological, and physical methods to control pests to a level that is less harmful, aiming to ensure human and animal health and increase forest productivity.
The main pests damaging Larix principis-rupprechtii in the Mengzi Forest Management Bureau include larch caterpillars, larch tussock moths, larch borer leaf flat bees, northern China larch sheath worms, gypsy moths, and larch cone flies.
First, the main leaf pests
(i) Dendrolimus superans (Butler)
1. Taxonomic Status: Lepidoptera, Bombycoidea, Bombycidae, Lasiocampidae
2. Distribution: Domestic provinces such as Heilongjiang, Jilin, Liaoning, Inner Mongolia, Hebei, Xinjiang; foreign countries like the Soviet Union, North Korea, Japan, and Mongolia.
3. Identification Characteristics
(1) Adults: Female adults are 28–45 mm long, with a wingspan of 70–110 mm, and dentate antennae. Males are 24–37 mm long, with a wingspan of 55–76 mm and feathery antennae. Body color and spot variation are significant, with wider forewings, wavy outer edges, and dark brown inner and outer horizontal lines. The outer transverse line is jagged, and there are eight dark spots on the sub-peripheral line, forming a three-character shape. The last two spots are nearly parallel to the outer edge when aligned. The middle class has a clear day shift, with light-colored markings in the center of the hind wings.
(2) Eggs: Oval, approximately 1.8 mm long and 1.6 mm wide, pale green at first, turning yellow, red, or dark red. They are arranged irregularly.
(3) Larvae: Mature larvae are 68–72 mm long, with great body color variation, ranging from smoke black, grayish black, to grayish brown. The head is brownish yellow, dark brown in the frontal area, and features a triangular dark brown spot in the center. There are pairs of blue and black poison hairs on the back and chest. The abdomen is black, with silver-white lateral hairs and sometimes inconspicuous markings. The eighth abdominal segment has a pair of dark blue hairs. The chest and abdomen have long, pointed tips, mostly spindle-shaped, without dentate protuberances at the tip.
(4) Pupae: Body length 40–60 mm, yellowish brown or dark brown, with dense golden short hair. Cockroaches are gray or gray-brown, with many blue and black larvae attached to the surface.
4. Occurrence Characteristics
The larch caterpillar has a life cycle of 2 years or 1 year. In the Mengzi Forest Management Bureau in Hebei Province, the larvae of the first and second generations survive the winter, starting to emerge when the daily average temperature drops below 9°C, and ending when the temperature stabilizes at 9°C, with the wintering larvae reaching 5 in mid-April. At the start of the month, the upper tree began to move, and the wintering mortality rate was 35%. Overwintering larvae feed on buds first, then consume entire leaves after they appear. When feeding, the chest foot clings to the pine needle and starts feeding from the tip. When disturbed, it falls to the ground and does not move. In late June, pods and phlegm began to form. In early July, it was the peak of phlegm; in late July, it was the end of phlegm; adults began to emerge in late July, and in late July and early August, they were eutrophic, and in mid-August, they emerged. At the end; feathering is more concentrated, adults have a strong phototaxis, usually at dusk and sunny evenings. After mating, they fly to the lush pine trees and spawn on the branches and needles in the middle and lower part of the canopy. In early July, the eggs began to appear. In August and mid-October, the spawning period was high. In the middle and late August, it was the end of spawning. The eggs became lumpy and arranged irregularly. Each female can lay between 128 and 515 eggs. Adults live 4 to 15 days. After 12 to 15 days of egg hatching, the newly hatched larvae are clustered on top of the shoots, and when disturbed, they droop and drop to other branches. Gradually scattered after 2 years of feeding, by the alarm no longer drooping, but directly fall to the ground. Larvae are 7 to 9 years old.
Larch caterpillars occur in leeward sunny, sparse, and dry larch pure forests. After more than 2 to 3 years of continuous drought, the larvae were harmed. After the pupa, due to the increase of natural enemies, the foodstuffs were in short supply, and the density of the larvae decreased. It was even difficult to see live worms. The unfavorable climate for this worm is the cold and wet weather with heavy rainfall and the torrential rain and low temperature after the larvae emerge out of the larvae. Such climate has obvious inhibitory effects on its occurrence.
5. Control Methods
Larch pine caterpillar is a devastating pest that is easy to occur and difficult to suppress. When formulating prevention and control measures, we must firmly grasp every weak link in the living environment of pine caterpillars, and comprehensively apply various prevention and control methods. Control in time makes it not a disaster.
(1) Forestry Measures: Forestry measures are the fundamental measures to increase the integrated pest resistance effect of pine forest ecosystem, exert the potential of self-control, and adjust the dynamics of pine caterpillars to avoid insect pests.
Reasonable afforestation: To create a mixed forest. As a result of its complex forest, mixed forests often have more natural enemies, and the microclimate is also relatively unfavorable to the growth and development of pine caterpillars, and it has certain barrier effects on the food of pine caterpillars. This is usually evaluated. The reason for the unfavorable growth of the pine caterpillar population in the mixed forest.
Reasonable dense planting: Forest land is too sparse, airy and transparent, which is often conducive to the growth and development of pine caterpillars. Appropriate dense planting is not only conducive to the growth and development of larch, but also a highly closed forest environment has a greater inhibition on the population of pine caterpillars.
(2) Improve forest management technology
Closing the mountains to cultivate forests: The management of forest cover damaged by the destruction of forest land and poor growth of larch is very beneficial to improving the forest condition, restoring soil strength and improving forest growth. The complex forest phase also exerts obvious control over the dramatic increase of the population of larch caterpillars.
Timely tending and transforming the sub-forests: timely nurturing is a necessary measure to promote the healthy growth of forest trees and transform the environment of larch forests.
(2) Artificial Control
1. Killing overwintering larvae: The severe occurrence of the larvae occurs between late November and late March of the following year. In the overwintering sites of pine caterpillars, such as stones, bark joints, weeds, artificial capture and then burned or contacted with chemical pesticides. This method can significantly reduce the population density.
2. Picking pods: After larvae have been pupated, they can be cut off or hooked off with scissors or wire hooks.
3. Picking eggs: The eggs of pine caterpillars are easy to find. Eggs are manually collected and disposed of in a centralized manner to reduce the density of insects in the second year.
(3) Chemical control: Spraying 4.5% high efficiency cypermethrin emulsifiable concentrate with No. 0 diesel at a ratio of 1:14 with a smoke machine to prevent and treat 4 to 5 years old pine caterpillar larvae. The control effect can reach over 95%. When controlling pine caterpillars of young larch, they can be sprayed with a Knife-type motorized sprayer and sprayed with a spray of 4.5% high efficiency cypermethrin 800 to 1500 times; and a stretcher-type “165 workers and peasants 36†high pressure sprayer can be used to prevent and control the forest. It can reach more than 95%, but its prevention and control costs are about 50% higher than those with a smoke machine. You can also use the poison pen to draw a ring in the trunk.
(4) Biological control measures
1. Protection and use of natural enemies: Parasitic insects: Trichogramma controls pine caterpillars, hangs eggs in the forest, hangs eggs on the shady side of the trunk and rises up against the wind. Put the bee on the bee's ability to move (radius 7 to 10 meters) 6 to 8 cards per acre can be put every day bee time can be 15:00 to 16:00 points, strong winds, heavy rain weather should not bee.
2. Use Beauveria bassiana to control pine caterpillars, which can be sprayed or sprayed. The Beauveria bassiana is sprayed in early May, with a daily temperature of 18°C and a humidity of 70%. It can be carried out on a cloudy day, after a rain or in the morning with dew. Temperature and humidity can not meet the requirements of bacteria breeding and development, the control effect is not good.
(5) Pollution-free prevention and control: Using a smoke machine to control 4th to 5th instar larvae: Spraying 1.2% bitter/fumarocyanine oil and 0# diesel oil at a ratio of 1:7, the control effect can reach over 92%; Efficacy of the combination of phenytoxil and No. 0 diesel in the ratio of 1:5, the control effect can reach over 90%; and the spray of 0.6% avermectin and No. 0 diesel in a ratio of 1:5. The control effect reached more than 92%.
(ii) Erectis ankeraria Staudinger
1. Taxonomic Status: Lepidopterac Geometridae
2. Distribution in China: Hebei, Inner Mongolia, Shaanxi, and abroad: Hungary. This worm is an important pest of larch. In the 1980s, the area of this insect was more than 400,000 mu in Weichang County, Hebei Province, and the maximum number of insects per plant was 20,000. The impact on high growth was extremely significant in 2 to 4 years after the victimization, and the diameter growth and volume growth were achieved when the loss rate was 100%. The effects are extremely significant.
3, identification characteristics
(1) Adults: female adult spindle-shaped, body length 12 ~ 16mm, no wings, only scaly protrusions. The head is dark brown with a white patch of white scales on the top of the head. The antennae, compound eyes are black, and antennae are filiform. The body is grey and white, with irregular dark spots. There are 1 pair of dark spots on the back of each section of the chest. The first section of the abdomen has 1 pair of dark spots. The rest of the sections are covered with dark spots from the midline and both sides of the dorsal midline. There is one side black line from the head and the compound eye. Slim, black, each section has 1 to 2 white ring spots. Male adults have a body length of 14-17mm and a wingspan of 38-42mm. The body is tan-brown with a pale yellow head and compound eyes are black. The tentacles are tentacles, tentacles are pale yellow, and caries are yellow-brown. The chest is densely covered with long-scaled hairs, yellowish-winged wings, irregularly brown spots on the front wings, and yellowish lines. The front wings are dark brown and have a large curvature. There is a dot on the middle chamber. The horizontal lines and round spots of the hind wings are more ambiguous than the front wings.
(2) Eggs: oval, 0.6-0.9mm, initially contaminated white, gradient milky white.
(3) Larvae: body length 27 ~ 33mm, yellow-green, brown head, rough shell, reddish brown pattern, upper lip light brown, lack of cut edge darker. Yellow and white tentacles, inner measurement with a dark brown dot. Body wrinkles, back, belly with 10 intermittent black lines. The valve line and the ventral midline are yellowish-green, with long oval pores and black edges.
(4) Pupae: 12-18 mm in length. The upper half of each segment has a round engraved dot, the lower half is smooth, the distal segment is brownish black, and it protrudes to the back. The thorns at the end of the thorns are juxtaposed with 2 thorns and extend obliquely toward the ventral surface. Oval shape, length 15 ~ 22mm.
4, the occurrence of characteristics in the forest area of Mengzi Forest Management Bureau a year, wintering eggs. In early May, when the average temperature reached above 9°C, hatching began. At this time, the larch buds had opened and the leaves were tender and about 3mm long. The newly hatched larvae ate in the vicinity of the newly-opened bud package, and the food intake increased after 3rd instar. Speed up, until the middle of June, the larvae will stop eating when they are approaching maturity. When the larvae are seriously damaged, they can eat up all the needles and have the characteristics of endangering the disaster. The larvae were 5 instars. In late June, the mature larvae drooped or fell directly to the ground, and then they crawled around to find a place to enter the earth. Generally distributed vertically in the soil from 3 to 5 cm above the ground surface, and the individual larvae in the litter layer. The larvae under the tree are relatively tidy, generally within 3 to 5 days. The flood season is longer, from the end of June to the end of September, about 80 days. In late September, quails begin to emerge. The eclosion time is mostly in the morning. The females are good at crawling and climb up after emergence. Males have a dead-dead habit and are in touch. At night, the eggs are prolific in the open cones of fruit and a few are produced in the bark joints. The greater the degree of canopy closure, the heavier the damage, the more the canopy closure of 0.85 or more, can all be harmed; artificial pure forest, hawthorn, and forest victims are heavy.
5, control methods
(1) Forest management measures: Tendering should be conducted in time, reasonable cutting should be conducted, and excessive logging should be prohibited.
(2) Manual control: The larvae have drooping drooping and accustomed grounds, and can kill the larvae after they fall.
(3) Biological control: protect and utilize natural enemies. From 1983 to 1984, the nuclear polyhedra virus of L. gmelinii was widely distributed in the forest of Larix principis-rupprechtii in the forest area of Mengfu. The incidence rate of larvae was more than 96%, which greatly reduced the incidence of the larvae in the following year.
(4) Chemical control
1 Liquid spray: It is required to work in the weather without rain or wind. With the use of 4.5% high efficiency cypermethrin EC 1000-2000 times, the canopy cover spray can prevent 2 to 3 instar larvae, and the control effect (after 2 days) can reach more than 95%. Advantages: Good control effect, especially for older larvae; Disadvantages: Large investment in labor.
2 Smog prevention and control is applicable to stands with a canopy closure of more than 0.6 and away from water sources. Using a fog machine to prevent and control the application of 4.5% high efficiency cypermethrin EC with a 0:1 diesel ratio of 1:16, the control effect (after 5 days) can reach over 94%.
6. Non-pollution prevention and control using a smoke machine to control 2 to 4 instar larvae: Spraying 1.2% bitter/cow EC and 0# diesel at a ratio of 1:8, the control effect can reach over 93%; 3% of discharge is high Efficacy of the combination of phenytoxil and No. 0 diesel in the ratio of 1:5, the control effect can reach more than 91%; spray of 0.6% avermectin and No. 0 diesel at a ratio of 1:7. The control effect can reach more than 92%.
(iii) Cephalcia lariphila (Wachtl)
1. Taxonomic Status Hymenoptera Megalodonoidea
Pamphiliidae Cephalcia Panzer
2. Distribution in China: Heilongjiang (Hailin), Shanxi (Guanshan Forest District), Hebei (Weichang County, Fengyi County), and foreign countries: Finland, Netherlands, Belgium, United Kingdom, Germany, Switzerland, Italy, Czechoslovakia, Russia (Irkutsk region).
3, identification characteristics
(1) Adults: Females are 10 to 12 mm in length. Black head; most of the lip base front and center, tentacles side area and the rear square pattern, the next two round spots in the middle unilateral eye, the long side of the side seam, the cheek and the posterior region of the posterior eye, and extending The fine lines connected to the square pattern on the side of the antenna are yellow-white. Most of the antennal shank segment, the back of the stem, black; whip red-brown, its darker end. Chest black; front and back of the chest plate most of the back, in the chest after the scutum posterior, mid-thorax scutellum rear near the square pattern, the middle chest scutellum on the pattern, fins are yellow-white. Translucent wings, microstrip yellowish, apex and outer edge slightly smokey brown; wing wings and wing veins dark brown; wing tail has a light brownish-brown transverse band leading to the trailing edge of the wings. The festival is full of yellow and the rest of the festival is black. The abdomen is black; both sides of the back plate, the rear edge of the second to the eighth back plate, and the rear edge of the web are all yellow. The lip base is flat; the frontal ridge is not prominent; the middle nest is shallow; the side seam, crown seam, and transverse seam are obvious; The engraved abdomen is finely detailed and has a fine, horizontal wrinkle-like appearance. Antennae 23 knots. The scorpion body length is 8-9mm. The head is black; along the cheeks and the posterior border of the eye, the posterior edge of the striated, most of the antennae side area, the base of the lip base and the center are yellow; the antennal shank section is black on the back, and the rest is reddish-brown and black on the tip. Chest black, both ends of the thoracodorsal plate and the fin base yellow-white; the first half of the leg section is yellow. The abdomen is black; both sides of the back panel and the holder are yellow. The engraved points on the top of the head and the back of the eye are denser than those of the females. Antennas 23 to 25 knots.
(2) Eggs: Long oval, slightly curved, 1.8 ~ 2mm long, the same color as the coniferous leaves at the time of first birth, silvery gray at the time of rapid hatching.
(3) Larvae: Mature larvae are 15 to 20 mm long, gray-brown. Head cover, tentacles, dark brown around the valve; tail and chest legs dark brown, later become grass green or green.
(4) Pupae: mouthparts, compound eyes, tentacles light green, tentacles up to the fifth quarter of the abdomen.
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