On July 16-18, the National Agricultural Technology Center held the 2018 National Corn and Cotton Pest Occurrence Trend Consultation and Monitoring Technology Seminar in Harbin, Heilongjiang Province. On the basis of summarizing the occurrence of diseases and insect pests in the early stage of corn, based on the comprehensive analysis of the current incidence of corn diseases and insect pests, corn cultivation methods and crop layout, combined with future climate trend predictions and other factors, it is expected that the overall incidence of diseases and insect pests in the middle and late stages of corn this year will be moderate, and the three generations of armyworms, ear stage corn borers, cotton bollworms, large spot diseases and brown spot diseases will be locally heavily occurred, and the end of July to the end of August will be the peak period for various diseases and insects.
First, the occurrence of diseases and insect pests in the early stage of corn
The pre-maize diseases and insects are mainly a generation of corn borer, a second generation of armyworms, a generation of grassland borers, a second generation of cotton bollworms, a two-point nocturnal moth, underground pests, thrips and blight, and the overall occurrence is light, the degree is close to that of previous years, the occurrence area is 318 million mu, of which 289 million mu of corn insect pests occur, and 28.5 million mu of corn diseases occur.
A generation of corn borer occurs more heavily in the north-northeast, and in most areas of the northeast, north China, Huanghuai, and southwest China, it is mild to moderate. At present, except for the northeast generation area, which is in the harm period, the second generation of corn borers in other areas has begun to be harmed.
The overall occurrence of second-generation armyworms is moderate, and high-density plots appear in parts of Heilongjiang, Liaoning, Inner Mongolia, Shaanxi and Shanxi, with a maximum of 1500 insects.
A generation of grassland borer in Inner Mongolia Xing'an League, Hulunbuir, Tongliao, Jilin Baicheng local heavy occurrence, maize and gray vegetables found high density of larvae, the highest amount of insects up to 15,000 head /hundred plants and 1,000 head / m2 respectively.
The two-point nocturnal moth occurs moderately in Shandong, Shanxi and Hebei, and in other Huang-Huai-Hai areas.
The second generation of cotton bollworm occurs lightly in north China, Huanghuai and northwest China, which is lighter than in the previous year.
Subsurface pests occur moderately to severely in parts of the northeast, north China and northwest China.
Thrips occur locally in North China and Northwest China.
Double-spotted fluorescent leaf beetle occurs in Inner Mongolia and Shanxi.
Pests such as beet nocturnal moths, snails, and brown-footed horned hordes and leaf beets have increased significantly in the Huang-Huai-Hai Sea.
Striated blight occurs moderately in most of the southwest;
Maize large spot disease in the northeast, north China and northwest China, brown spot disease in the Huang-Huai-Hai region gradually entered the hazard period (see Table 1 of the occurrence area of each disease and insect).
Second, the trend of diseases and insect pests in the middle and late stages of corn
(1) The type and area of occurrence
In the middle and late stages of maize, the diseases and insects are mainly drill moth, leaf-eating, stinging pests and leaf diseases, and corn borer, cotton bollworm, aphid, large spot disease, small spot disease and brown spot disease occur more commonly and are more seriously damaged; leaf mites, double-spotted firefly leaf beetles, curved leaf spot disease, silk smut disease, powdery mildew, striated blight, stem rot, ear rot and gray spot disease cause certain harm in some areas. It is estimated that 844 million mu of diseases and insect pests will occur in the middle and late stages of maize, 571 million mu of insect pests, and 274 million mu of diseases (see Table 1 for the estimated occurrence area and key areas of each disease and insect).
(2) Degree of occurrence and key areas
1. Drill moth pest. The first generation of corn borer occurs more heavily in Heilongjiang and northeastern Inner Mongolia; the second generation occurs in the southwest of Heilongjiang, and occurs more heavily in eastern Inner Mongolia, western Jilin, southeastern Liaoning, Sichuan, and Xinjiang, and moderately in other regions; the third generation occurs more heavily in Hebei, Shanxi, Henan, and Hubei, and occurs in other regions with light to moderate occurrence. Panicle-stage cotton bollworm occurs moderately in the Huang-Huai-Hai, northwest and southern northeast regions, and peach borer is more serious in the Huang-Huai-Hai region.
2. Leaf-eating pests. The overall occurrence of three generations of armyworms is moderate, and there will be areas with high density concentration hazards in northeast China, north China, northwest China, and Huanghuai; second-generation grassland borers may have more heavy occurrence in eastern Inner Mongolia and their surrounding areas; double-spotted firefly beetles occur more heavily in Shanxi, Inner Mongolia, and Heilongjiang, and most other areas are mild to moderate.
3. Stinging pests. Aphids occur moderately in most parts of Northeast China, North China, Northwest China, and Huanghuai, while leaf mites occur in most parts of Northwest China and North China in mild to moderate size.
4. Diseases. Large spot disease occurs moderately in the eastern part of northeast China, with moderate occurrence in the central and western parts of northeast China, northern North China, eastern northwest china, and southwest China; moderate occurrence of small spot disease in southern huanghuai and southwest china; medium incidence of brown spot disease in huanghuaihai and eastern inner Mongolia; moderate occurrence of curvular spore leaf spot disease in the huanghuai region and southern northeast China; moderate occurrence of gray spot disease in the mountains of southwest china and most of northeast China; moderate to heavy occurrence of striated blight in most of the southwest and local areas of northeast China; and the possibility of heavy occurrence of southern rust in southern Huanghuai and other places There is a high risk of stem rot in the Huang-Huai-Hai region. In addition, diseases such as powdery mildew and ear rot will also cause certain harms in local areas.
Table 1 Predicted area and area of maize pests and diseases in the early stage and the middle and late stages
3. Basis for forecasting
(1) The base of grassland borer and disease is high, and the base of corn borer, armyworm and cotton bollworm is low
The weighted average residual insect volume of the second-generation armyworm types in Heilongjiang, Liaoning, Inner Mongolia, Sichuan, Yunnan and Guizhou is between 1.2-6 heads/m2, and other provinces are less than 1 head/m2; the number of second-generation armyworm adult insects monitored recently, Heilongjiang Zhaozhou, July 7-17, heilongjiang, the cumulative detection lamp is 37 lure moths, the cumulative lure moth is 124 moths, the Jilin Gongzhuling Peak daily lure moth is 36, the Liaoning Zhangwu 9-13 day moth peak appears, the cumulative moth peak daily lure moth in 7 monitoring points is 998, and the single lamp maximum lures moth is 142. In the first half of July, the monitoring of high-altitude monitoring lights in various places, Heilongjiang Shuangcheng accumulated 31 lures, 8 peak day lures, 71 peak moths in Horqin District, Inner Mongolia, 41 moths in Laizhou, Shandong, 8 moths in Fengtai, Anhui, 77 moths in Gansu Zhuanglang, 15 peak days, the amount of moths in the above monitoring points was lower than the same period last year; Jilin Changling accumulated 1398 moths, 750 moths on July 13, the peak day was one week earlier than usual, the amount of lures was 7 times that of the previous year; Liaoning Zhangwu accumulated 285 moths. The amount of moths attracted was 3 times that of the previous year, and the total number of moths in Luan County, Hebei Province was 1642, the amount of moths was 40 times that of the previous year, and the number of peak moths was 805.
The occurrence area of adults and generations of larvae of grassland borer overwintering is large and the degree of harm is high, and the number of larvae in the farmland is 1.27 heads/m2 in Inner Mongolia, 0.01 heads/m2 and 0.06 heads/m2 in Jilin and Ningxia, respectively. Recently, a generation of adult insect trap moths peaked in some parts of Inner Mongolia, with 20,000, 47,000 and 32,000 moths in Ulanhot high-altitude monitoring lamps on July 9-11, 7520 lures moths on the 13th, 592, 1984 and 848 moths on July 9-11, and 1290 moths on the 13th. Tuquan County high-altitude monitoring lights on July 11 to lure more than 10,000 moths, 13 days to lure 2950 moths, high-altitude monitoring lights near the 100-step moths 1500-2000 heads, farmland around the grass, grass beach 100 steps moths only a few. On July 11, Hulunbuir Arong Banner attracted 12,000 moths, and 300-600 moths in hailar, Moqi wasteland and gray vegetable dense areas. Heilongjiang Nenjiang detection and reporting lamp on the 13-16th, the cumulative number of lure moths 136, 5 hundred step moths.
The second generation of cotton bollworms in North China, Northwest China and most of Huanghuai are generally light, the base number is low, occurring in corn, peanuts, soybeans, vegetables, Chinese medicinal materials, oil sunflowers and other crop fields, Tianjin hundred plants with the highest 10 insects, Henan average 100 insects 2, Hebei general 100 plants of insects 1-5, re-occurrence of plots 8-20, the amount of residual insects is more than last year.
The average number of 100 insects in a generation of corn borers is counted in various places, 47 in Heilongjiang, 64 in the generation area after winter, 40 in Guizhou, 31 in Chongqing, 10-27 in Hunan, Jiangsu, Shandong, Jilin, Liaoning and Inner Mongolia, and other provinces are below 10, and most of the bases are low.
Diseases such as maize large spot disease and brown spot disease occur year after year, and the proportion of straw returned to the field is gradually increasing, resulting in an adequate pathogen base. At present, diseases such as large spot disease, striped blight, small spot disease and rust disease in corn have begun to occur in various places and have shown a gradual aggravation trend. Among them, the rate of maize large spot disease in Inner Mongolia is 5%-20%, the general incidence rate of Shanxi is 1%-2%, the highest is 5%, the average disease rate of Hebei is 8.5%, the highest disease rate is 21%, the rate of Jilin diseased plant is 1.1%, the rate of Ningxia Pengyang and Yuanzhou is 4.8% and 15%, and the disease leaf rate is 1.6% and 1.8%, respectively.
(2) Maize varieties and planting systems are conducive to the occurrence of a variety of diseases and insect pests
There are few disease- and insect-resistant varieties in corn planting in China, and the proportion of corn large-spot disease-susceptible varieties such as Xianyu 335 is high. The continuous planting method of maize in the north is conducive to the occurrence of diseases and insects in large areas, and some extensively managed plots are conducive to the concentrated occurrence of armyworms and grass borers. At the same time, the plants are tall and the fields are closed in the late growth stage of corn, which is difficult to prevent and control corn diseases and insect pests, resulting in an aggravation of the degree of pests and diseases.
(3) Future meteorological conditions are favorable for the occurrence of corn diseases and insects in most areas
According to the forecast of the National Climate Center, from the second half of July to the first half of August, the precipitation in the eastern part of the northwest region, north China, the south of the northeast region, the northern part of Huanghuai and other places will be more than 20%-50%, and the temperature in most of the north will be close to the perennial, which is conducive to the exchange and population reproduction of migratory pests such as armyworms, grassland borers and cotton bollworms in the above areas, and is also conducive to the occurrence of wet-loving diseases and insects such as corn borer, large spot disease, small spot disease, brown spot disease, curvalin leaf spot disease and so on. The precipitation in the south of Huanghuai and the north of Jiangnan is 20-50% less, which is more favorable to the occurrence of drought-loving pests such as cotton bollworms and aphids in these areas. It is expected that the number of typhoons landing in China is 3-4, which is more than the same period of the year (about 2), and the average intensity of the landing typhoons is stronger, which will be conducive to the spread of rust in the Huang-Huai-Hai in the south.
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