The most common pests and diseases of rice are three worms and three diseases, the three insects are drill heartworm, rice longitudinal leaf borer, rice planthopper, the three diseases are striped blight, rice blast disease, and white leaf blight.
Rice drill heartworm, in fact, is a general term, in the actual planting process, we are used to the two borer, three borer, called drill heartworm. Drill heartworm is a major problem that threatens the high yield and stable yield of rice, and unscientific control will reduce rice yield by 5%-10%, and serious yield can be reduced by about 30%.
Today Xiaolongren takes you to learn and understand how to control rice drill heartworms, mainly from the following 5 aspects to introduce:
(1) Introduction to drill hearts
(2) Morphological characteristics
(3) Harmful characteristics
(4) Occurrence distribution
(5) Prevention and control time
(6) Prevention and control methods
Dihua borer is a genus of Lepidoptera, a family of moths, which is one of the most harmful and frequent pests in rice in China. There are distributions in all rice areas in China, mainly in the Yangtze River Basin and the rice areas south of the river basin, and the number of occurrences has shown a significant increase in recent years. In addition to harming rice, the two borers can also harm russet, corn, sorghum, sugarcane, rapeseed, broad beans, wheat and weeds such as reeds, barnyards, and Li's grass.
Trichemotium borer (drill heartworm) belongs to the order Lepidoptera, a family of borer moths, which is widely distributed in the rice area south of the Yangtze River Basin, especially along the river and coastal plains. It has a single diet and specializes in rice.
Chilo
Adults: Adults have wingspans of about 20 mm in males and 25-28 mm in females. The head is pale greyish brown , with a white to smoky forehead , rounded , and pointed apex. The thorax and wing basal are white to off-white with brown tinge. The forewings are yellowish brown to dark brown , with purple-black spots at the apex of the middle chamber and 3 spots lined up in a diagonal line below the middle chamber. There are 7 black spots on the outer edge of the forewings. The hindwings are white , slightly brown near the outer edge of the wings. Females are slightly paler than males , with yellowish-brown forewings and white hindwings.
Eggs: flat oval, there are more than 10 to 100 grains to form eggs, arranged into fish scales, milky white at the beginning of birth, gray-black when hatching.
Larvae: 20–30 mm long, with 5 brown longitudinal lines on the dorsal back and a grayish-white ventral surface.
Pupae: about 10–13 mm long, pale brown, 5 brown longitudinal lines can still be seen on the anterior back, the middle three are more pronounced, and gradually blurred in the later stages, and the foot extends to the end of the wing bud.
Trischemistry
Adults: 9–13 mm long and 23–28 mm wing spread. The female forewings are nearly triangular , pale yellowish-white , with a distinct black spot in the center of the wing and a clump of yellowish-brown fur at the end of the abdomen ; the male forewings are pale greyish brown with a small black spot in the center of the wings , with a dark brown tlanch diagonally from the apex of the wing to the center.
Eggs: oblong, densely packed into pieces, dozens to a hundred grains each, the eggs are covered with brown villi, like half a grain of moldy soybeans.
Larvae: 4-5 years. At first hatching, it is grayish-black with a white ring at the junction of the thorax and abdomen. Aged 14–21 mm long, the head is pale yellowish brown, the body is pale yellowish green or yellowish white, from the age of 3 years, the dorsal midline is clearly visible. Gastropods are more degenerate.
Pupae: yellow-green, golden yellow (female) or silvery grey (male) before feathering, male pupae hindfoot extend to the seventh abdominal segment or slightly more, female pupae hindfoot extend to the sixth abdominal segment.
The difference between the dimorph and the tricolor borer 1. Shape The dimorph borer is flattened and oval in shape, and is larger than the tricolor borer. The forewings are nearly rectangular, the hindwings are white, with seven small black dots on the outer margin, and the larvae have 5 dark brown longitudinal lines on the back. There is an inconspicuous dark spot in the lower corner of the middle chamber of the triad borer, with a black head in the early instar and a pale black chest and abdomen. 2. Spawning The eggs of the dimorph are arranged irregularly in scales, in seedlings, tillering stage, the eggs are laid 3-7 cm from the leaf tip on the front of the leaf, and in the late tillering stage, they are laid on the leaf sheath more than 6 cm above the water surface. The eggs of the three borers have three layers, shaped like half a soybean, and are mostly produced on the leaves, and the secondary is on the leaf sheath. After the spikes emerge, they rarely lay eggs, only on the green sword leaves. 3. Harmful crops The three borers are only harmful to rice; In addition to rice, the two borers are also harmful to white, maize, sugarcane, reeds and other grasses. 4. Degree of harm The ability of the two borers to infest rice is stronger than that of the three borers, and three generations occur a year. Larvae overwinter in rice roots, straw, russet, etc. At the turn of spring and summer, the first generation of moths blooms from May to June, the second generation moths bloom in July, and the third generation moths bloom from August to September. The trinity borer occurs in exactly four generations, with overwintering larvae starting pupating in April, the first generation in May, the second generation in late June to early July, the third generation in August, and the fourth generation in mid-to-late September.
Dry heart seedlings and dead sheaths appear in the tillering stage of rice; dry pregnant ears and white ears appear at the gestational and panicle extraction stages; half-withered ears and insect-injured plants occur during the filling stage and milk maturity stages, and the grains are increased, and they are easy to bend in case of strong winds.
After the larvae moths into the rice stem, the tip of the sword leaf turns yellow, the severe heart leaf withers and dies, there are borer holes on the affected stem, there is very little insect feces outside the hole, there is more insect feces inside the stem, yellow, and the rice stalks are easy to break. Different from the dry heart seedlings caused by the damage of the borer.
The dead heart seedlings caused by the infestation of the dimorph borer, the larvae first cluster on the inner side of the leaf sheath to eat as a pest, the leaf sheath appears water-stained macula, the back leaf sheath is yellow, and the leaves are gradually dead, called the dry shoot stage.
The three borers are infested by the larvae borer stems, forming a dry heart at the tillering stage, forming a dead pregnant panicle and a white panicle from the gestational panicle to the panicle extraction stage, and turning the plant into a pest also forms an insect injury plant. "Dead heart seedlings" and "white ears" are the main symptoms of rice plants after they are damaged.
Dihua borer is an important insect pest of rice and other grass crops, widely distributed in many countries in Eurasia, with many wintering places and plant hazards.
Domestic distribution: North to Keshan County, Heilongjiang, south to Hainan Island, but its main distribution areas are Hunan, Hubei, Sichuan, Jiangxi, Zhejiang, Fujian, Jiangsu, Anhui, Guizhou, Yunnan and other Yangtze River basins and the main rice areas south of them.
The tricolor borer is an important rice insect in tropical to southern temperate zones in Asia.
Domestic distribution: The Yangtze River Basin and the main rice areas south of it are the most harmful areas along the coast and along the river plains. In recent years, there has been a trend of northward expansion.
The National Agricultural Technology Extension Network released the "Technical Plan for the Prevention and Control of Major Rice Diseases and Insect Pests in 2020" of the Department of Disease and Pest Control, which is expected to occur more frequently and locally; the occurrence of the three borers in South China and Southwest China is moderate.
Rice dimorph borer mostly occurs at 1m from the rice field pond, observe the stem at about 10 cm on the water surface, the leaf sheath has an irregular yellowing phenomenon, heavy with brown stripes, then open the leaf sheath will find dimorph larvae inside.
At the tillering stage, the pesticide is applied when the rate of dry sheath bushes reaches 8-10% or the rate of dry sheath plants is 3%, and the medicine is applied at the peak stage of egg hatching at the panicle stage, focusing on the prevention and control of rice fields with a large amount of residues in the previous generation and the incubation period of contemporary borer eggs coinciding with the panicle extraction stage of rice.
The better control time of rice borer should be determined by both insect and seedling conditions.
When controlling dry heart seedlings, insect conditions are the mainstay, that is, the peak period of egg block incubation is applied for control, and the number of egg blocks per mu reaches 40 rice fields, and the day after the bottom of 50% of the eggs becomes black, it is the peak period of incubation, which is a better period for the prevention and control of dry heart seedlings.
The prevention and control of white ears should be mainly based on seedling conditions, that is, in the appropriate period of prevention and control, look at the growth period of rice and reach the stage of breaking the mouth and extracting ears, which is the best period for the prevention and control of white ears.
First, basic prevention techniques
1． Ecological regulation.
(1) Retain functional weeds in the fields and fields, plant flowering plants such as sesame, soybean, cosmos, and sulfur chrysanthemums, and conserve natural enemies such as parasitic bees, spiders, and black-shouldered green blind bugs;
(2) Planted lure plants such as vetiver on the side of roadside ditches and machine ploughing paths, with a bush spacing of 3-5 meters, reducing the population base of borers.
2． Agronomic measures.
(1) Ploughing and irrigating to kill pupae. In the pupal stage of the overwintering generation borer, the winter idle field and green manure field were ploughed uniformly, and the rice pile was submerged with deep water for 7-10 days, reducing the insect source base.
(2) Fitness cultivation. Strengthen water and fertilizer management, timely drying of fields, avoid heavy application and partial application of nitrogen fertilizers, appropriately increase the application of phosphorus and potassium fertilizers, and improve the stress resistance of rice.
(3) Clean the countryside. Low stubble harvesting is carried out, and the mud is separated from the rice, destroying the overwintering site of the larvae and reducing the amount of borer residue.
Second, the priority of green prevention and control technology
1． Transplant with medicine.
2-3 days before transplanting seedlings, an aspirant agent is applied, and transplanted with medicine to prevent drill heartworms.
2． Physical barrier to seedlings.
The whole process of covering the seedlings with 20-40 mesh insect control nets or 15-20 g/m2 non-woven fabric blocks the mediator insects.
3． Sexual pheromone booby-trap and mating interference.
In the moth stage of the overwintering generation of dimorphic borer, the use of pheromones is concentrated, and the harm is mitigated by cluster booby-trap or interference mating. Swarm booby traps use volatile cores (lure cores) and dry moth traps with an effective period of more than 3 months, with an average of 1 set per mu, and the height is 50-80 cm from the ground at the bottom end of the trap. Mating interference adopts a high-dose pheromone intelligent spraying device, set up every 3 acres, and sprayed every 10 minutes from evening to sunrise.
4． Release the rice borer red-eyed wasp.
The dimorph moth releases the red-eyed bee of rice borer at its peak, releasing bees 2-3 times per generation, with an interval of 3-5 days, placing 5-8 points evenly per mu, and releasing 8000-10000 heads/mu each time. In the high temperature season, it is advisable to release bees in the evening, and the height of the bee card placement is 5-20 cm above the top of the plant at the tillering stage and 5-10 cm below the top of the plant at the panicle stage, and the release ball can be directly thrown into the field.
5． Protection and prevention from the end of pregnancy to the panicle extraction stage.
From the end of the pregnant ear to the fracture stage of rice, according to the main target of the panicle stage, the drug is combined and the heartworm is pre-drilled.
Third, chemical control
There are more than 3,000 drugs for the prevention and control of rice borers and borers, but there are six main types of varieties registered on the pesticide information network for the control of borer pests, namely:
1. Insecticidal single, insecticidal double, insecticidal ring, borericid, butylthio gram Budweiser;
2. Bacillus thuringiensis;
3. Triazoliphos, octylthion, chlorpyrifos, dichlorvos, acetylmethaphos, propyl bromophos, borer thion, water amine thion;
4. Avermectin, methylaminoavemectin benzoate;
5. Chlorantraniliprosis benzamide, fiprox bisamide, tetrafluorospermamide (9080);
6. Carbohydrazine, methoxychlorhydrazide, carbohydrazide.
It must be done to treat the 1st generation, which can not only protect the seedlings, but also suppress the density of the insect population of the next generation. Within 3 days after the peak hatching of the dimorph borer in the general year, the medicine is sprayed to control the dead sheath and dry heart seedlings. In the incubation of various types of rice fields from the peak period of hatching to the peak of hatching, the drug is used to control insect injury plants, dead pregnant ears and white ears.
30-50 ml per acre with 5% fluolamide emulsion,
or 480gl chlorpyrifos emulsion 80~100ml,
or 18% insecticidal dihydrate 200ml,
or 80% insecticidal monosoluble powder 40g,
or 20% acetyl methylamine phosphorus emulsion 50-60ml per acre,
or 20% acetyl methylamine phosphorus emulsion 50~ 60g per side,
Or 20% triazolium emulsion 100ml, add 30-50kg of water, spray evenly. (Data from "China Plant Protection Pest Atlas and Control Treasure Book")
Copywriting & Typography / Zhang Dapeng
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