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Pest in corn production - corn borer
Corn borer is a worldwide foraging pest, which is divided into Asian corn borer and European corn borer. In China, the Asian corn borer is the dominant species. In addition to the report on the Qinghai-Tibet Plateau corn area, the rest of the corn producing areas have occurred to varying degrees. Corn is very glutinous. There are about 25 host plants identified in China, which mainly harm corn, sorghum and millet, and also harm to hemp and cotton. Feeding corn heart, stems and ears with larvae is the most serious pest in corn production. Corn borer seriously harms corn in the occurrence area, especially in the process of corn hybrid seed production, if the damage of corn borer is not timely and effectively prevented, the stalk rate will reach more than 90%, and the stalk fold rate will be 30% to 50%. The rate of damage to the ear was 79%, which not only caused serious reduction in yield, but also the germination rate, clarity and fullness of the seeds were not up to standard, and the appearance of the seeds was extremely poor.
First, the morphological characteristics Corn genus Lepidoptera, Scorpionidae. The adult body is 12 to 15 mm long and has a wingspan of 24 to 35 mm. The male moth has a yellow-brown front wing with two brown wavy horizontal lines, two dark spots between the two lines, and a brown wide band near the outer edge. The hind wings are grayish or taupe. Female moths resemble male moths but are lighter in color. The egg is flat and elliptical, with a size of 1.0mm?.8mm. It is milky white at the time of initial birth, and has a yellowish gradient. Often 20 to 60 grains are arranged in a fish scale to form an egg mass. The larvae are 5 years old. The mature larvae are about 25mm long, with a reddish-brown on the back, a milky white belly, a clear back line, and a dark brown sub-back line on both sides. There are 4 round hairs on the back of the middle and back chest, and 2 bristles per tumor. There are two rows of hairy tumors on the back of the 1st to 8th abdominal segments. The front row is 4 large and the rear row is 2 small. The 9th abdominal segment has 3 hairy tumors and the center is larger. It is a bedding, the body length is about 15 ~ 18mm, yellow-brown, the back of the abdomen 1st to 7th section has a horizontal wrinkle, the hip spine dark brown.
Second, the law of occurrence From the north to the south 1 year can occur 1 to 7 generations, the old larvae overwinter in the host straw, cob, the larvae below 4 years old can not overwinter. In the spring, the pupa is feathered, and the adult has phototaxis and strong inducement. The egg is produced on the back of the leaf, and there are more near the midrib. Each female moth can lay 10 to 20 eggs, a total of 300 to 600. Larvae can spread the hazard, and it has the characteristics of stimulating sugar, touching (requiring the whole body to keep contact with plant tissues as close as possible), dampness and lightening. Before the 4th instar larvae, most of the larvae had high sugar content, high humidity, heart plexus, tassel, and the top of the filament at the top of the ear, and the leaf mites. In the corn and sorghum heart larvae, the larvae are concentrated in the heart leaves, and they feed in the rolled young leaves. After the leaves are pulled out, they form a small hole in the horizontal row. In severe cases, the heart leaves bite badly and cannot be pulled out normally. Delayed, affecting growth. The larvae are concentrated in the young tassels during snoring. After the filaments are extracted, they can be concentrated on the top of the filaments and the ears of the ears. Other birth stages. The larvae are scattered in the stems of the male stalks, stems, stalks of the ears, and the stalks of the cobs. The light ones affect the nutrient transport, the heavy ones break the stems, and the stems are broken and cut. In the general year, the yield of spring corn is reduced by about 10%. Summer corn production is reduced by 20% to 30%, and in the re-occurrence year, production is reduced by more than 30%. Studies have shown that there is no migratory phenomenon in the wintering stage of corn borer. The local pests are mainly local, and the overwintering larvae are revived, and the adult feathers lay eggs and the eggs hatch larvae need to absorb water or high humidity.
3. Comprehensive prevention and control 1. Before the wintering of the insects (before the end of March), the stalks and cobs of the wintering hosts such as corn are treated, which is an effective measure to eliminate the wintering larvae and reduce the number of overwintering insects; 2. In the adult stage , setting black light and sexual attractant to trap adult; 3. planting insect-resistant varieties; 4. starting at the peak of corn glutinous spawning, or starting from 1 to 2 eggs per 100 corn, releasing Trichogramma every 667 square meters 10000 heads, once again every 5d, can effectively control the damage of corn borer. It can also be evenly sprayed in the incubation period of Corn Cob eggs with 200 times solution of Bt emulsion containing 10 billion spores per ml; 5. In the corn heart leaf stage, 3% carbo granules can be used, and the granules can be used to spray the vials. Quantitative withdrawal of corn heart leaves, 1 g per plant. At the ear of corn, use 50% dichlorvos EC 800 times solution, or 90% trichlorfon 1000 times solution, 5-10 mL per plant, and inject the male tassel of the male. It is also possible to drop a few drops of the above-mentioned medicine on the base of the filament at the top of the ear, and the liquid can penetrate into the filament and smoke the larvae which are harmful at the top of the ear.
4. Three methods for predicting the suitable period of corn glutinous rice control 1. Hand-kneading method: When the corn tassel has just begun to enter the horn, the base of the horn can be felt by hand and the base of the stalk can be felt, but from the horn When you can't see the male, it is the end of the heart leaf, usually 5 to 7 days away from the male.
2. Stripping method: When the corn will enter the snoring period, sample the representative corn leaf plexus, peel off the green leaves, and spread the remaining yellow and white leaves leaf by leaf, such as 2 to 3 pieces. After the tassel is exposed, it is the end of the heart leaf; if the 4 to 6 leaves are unfolded, the tassel is seen, which is the middle of the heart.
3. Number leaf method: According to the number of leaves at the end of corn heart leaf is about equal to the total number of leaves of this product plant minus 2, this method is simple and easy to master.
Generally, corn is in the late or middle stage of heart, and it is suitable for controlling corn borer. It can be seen that the pest report is timely carried out, the plant quarantine is emphasized, the breeding of cultivars and the prevention and control of cockroaches are carried out, and the granule treatment of the horns is focused on, and the wintering host is the key to control corn mash.
First, the morphological characteristics Corn genus Lepidoptera, Scorpionidae. The adult body is 12 to 15 mm long and has a wingspan of 24 to 35 mm. The male moth has a yellow-brown front wing with two brown wavy horizontal lines, two dark spots between the two lines, and a brown wide band near the outer edge. The hind wings are grayish or taupe. Female moths resemble male moths but are lighter in color. The egg is flat and elliptical, with a size of 1.0mm?.8mm. It is milky white at the time of initial birth, and has a yellowish gradient. Often 20 to 60 grains are arranged in a fish scale to form an egg mass. The larvae are 5 years old. The mature larvae are about 25mm long, with a reddish-brown on the back, a milky white belly, a clear back line, and a dark brown sub-back line on both sides. There are 4 round hairs on the back of the middle and back chest, and 2 bristles per tumor. There are two rows of hairy tumors on the back of the 1st to 8th abdominal segments. The front row is 4 large and the rear row is 2 small. The 9th abdominal segment has 3 hairy tumors and the center is larger. It is a bedding, the body length is about 15 ~ 18mm, yellow-brown, the back of the abdomen 1st to 7th section has a horizontal wrinkle, the hip spine dark brown.
Second, the law of occurrence From the north to the south 1 year can occur 1 to 7 generations, the old larvae overwinter in the host straw, cob, the larvae below 4 years old can not overwinter. In the spring, the pupa is feathered, and the adult has phototaxis and strong inducement. The egg is produced on the back of the leaf, and there are more near the midrib. Each female moth can lay 10 to 20 eggs, a total of 300 to 600. Larvae can spread the hazard, and it has the characteristics of stimulating sugar, touching (requiring the whole body to keep contact with plant tissues as close as possible), dampness and lightening. Before the 4th instar larvae, most of the larvae had high sugar content, high humidity, heart plexus, tassel, and the top of the filament at the top of the ear, and the leaf mites. In the corn and sorghum heart larvae, the larvae are concentrated in the heart leaves, and they feed in the rolled young leaves. After the leaves are pulled out, they form a small hole in the horizontal row. In severe cases, the heart leaves bite badly and cannot be pulled out normally. Delayed, affecting growth. The larvae are concentrated in the young tassels during snoring. After the filaments are extracted, they can be concentrated on the top of the filaments and the ears of the ears. Other birth stages. The larvae are scattered in the stems of the male stalks, stems, stalks of the ears, and the stalks of the cobs. The light ones affect the nutrient transport, the heavy ones break the stems, and the stems are broken and cut. In the general year, the yield of spring corn is reduced by about 10%. Summer corn production is reduced by 20% to 30%, and in the re-occurrence year, production is reduced by more than 30%. Studies have shown that there is no migratory phenomenon in the wintering stage of corn borer. The local pests are mainly local, and the overwintering larvae are revived, and the adult feathers lay eggs and the eggs hatch larvae need to absorb water or high humidity.
3. Comprehensive prevention and control 1. Before the wintering of the insects (before the end of March), the stalks and cobs of the wintering hosts such as corn are treated, which is an effective measure to eliminate the wintering larvae and reduce the number of overwintering insects; 2. In the adult stage , setting black light and sexual attractant to trap adult; 3. planting insect-resistant varieties; 4. starting at the peak of corn glutinous spawning, or starting from 1 to 2 eggs per 100 corn, releasing Trichogramma every 667 square meters 10000 heads, once again every 5d, can effectively control the damage of corn borer. It can also be evenly sprayed in the incubation period of Corn Cob eggs with 200 times solution of Bt emulsion containing 10 billion spores per ml; 5. In the corn heart leaf stage, 3% carbo granules can be used, and the granules can be used to spray the vials. Quantitative withdrawal of corn heart leaves, 1 g per plant. At the ear of corn, use 50% dichlorvos EC 800 times solution, or 90% trichlorfon 1000 times solution, 5-10 mL per plant, and inject the male tassel of the male. It is also possible to drop a few drops of the above-mentioned medicine on the base of the filament at the top of the ear, and the liquid can penetrate into the filament and smoke the larvae which are harmful at the top of the ear.
4. Three methods for predicting the suitable period of corn glutinous rice control 1. Hand-kneading method: When the corn tassel has just begun to enter the horn, the base of the horn can be felt by hand and the base of the stalk can be felt, but from the horn When you can't see the male, it is the end of the heart leaf, usually 5 to 7 days away from the male.
2. Stripping method: When the corn will enter the snoring period, sample the representative corn leaf plexus, peel off the green leaves, and spread the remaining yellow and white leaves leaf by leaf, such as 2 to 3 pieces. After the tassel is exposed, it is the end of the heart leaf; if the 4 to 6 leaves are unfolded, the tassel is seen, which is the middle of the heart.
3. Number leaf method: According to the number of leaves at the end of corn heart leaf is about equal to the total number of leaves of this product plant minus 2, this method is simple and easy to master.
Generally, corn is in the late or middle stage of heart, and it is suitable for controlling corn borer. It can be seen that the pest report is timely carried out, the plant quarantine is emphasized, the breeding of cultivars and the prevention and control of cockroaches are carried out, and the granule treatment of the horns is focused on, and the wintering host is the key to control corn mash.
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