tuoqiu agriculture chemical
occurrence dynamics and next-stage trend of major diseases and insect pests in middle and late rice
according to the information from the national agricultural technology extension service center, currently, the main rice producing areas are in a critical period of yield formation. among them, south china, jiangnan middle rice, and northwest and northeast single-cropping rice are in the booting to heading stage, south china, jiangnan late rice and the middle and lower reaches of the yangtze river, jianghuai single-cropping rice is in the stage of turning green to tillering and jointing. as of august 12, the cumulative incidence of major rice diseases and insect pests was 583 million mu, of which the cumulative incidence of rice planthopper, rice leaf roller and rice blast was 161 million mu, 120 million mu, and 20.62 million mu respectively. after vigorous monitoring and control in various places, the occurrence situation in the early stage was relatively stable; however, the number of "two migration" pests under the lamp has increased rapidly in the middle and lower reaches of the yangtze river, eastern and southern coastal rice areas recently. diseases such as blast and southern rice black-streaked dwarf disease are still in the critical period of local susceptibility, and the occurrence of major diseases and insect pests in middle and late rice is still severe.
(1) rice planthopper
from late july to mid-august, due to the successive harvesting of the main early rice producing areas, the excessive rainfall in the central and eastern rice areas, and the northward movement of typhoons "fireworks", "chapaka" and "lubi", rice planthoppers were found in the middle and lower reaches of the yangtze river. , in the eastern and southern coastal areas, there are obvious insect peaks under the lamp. according to the monitoring of 239 stations in the national rice disease and insect monitoring regional station, during this period, the cumulative number of insects attracted by rice planthopper lamps in southern rice areas was 166,000, and the average number of insects attracted by a single lamp per day was 43.5, and the proportion of brown planthopper was 39.3%, a year-on-year an increase of 6.8%. from the end of july to the beginning of august, the average weekly cumulative number of trapped insects at a single point in each province is generally 400-500 in the middle and lower reaches of the yangtze river, an increase of 1.5-6.2 times from the previous month, and 1,300 in fujian and zhejiang, an increase of 6.2 times and 51.4 times from the previous month respectively; , yinzhou, zhejiang (july 30), and huian, fujian (july 31) attracted 14,000 insects per day. in early and late august, the number of insects under the lamp has dropped significantly. the average weekly cumulative number of insects in each province is generally 50-400. however, there are still peaks of insects under the lamp in the coastal rice areas of south china, including xianyou in fujian, tongan and chaozhou in guangdong. there are more than 10,000 insects per day in a single lamp, and xianyou (august 5) has a maximum of 59,000.
through timely prevention and control, the amount of rice planthopper field insects has been effectively controlled. at present, the average number of clumpworms in rice areas in the southwest, south of the yangtze river, and the middle reaches of the yangtze river is generally 300-900 heads, which is the same as the previous year; in some fields, the number of clump insects reached 30,000 to 100,000, which is a large occurrence indicator.
(2) rice leaf roller
from late july to mid-august, the rice leafroller showed obvious immigration peaks in many places in the south of the yangtze river and the lower reaches of the yangtze river. according to the monitoring of 239 stations in the national rice disease and pest monitoring station, during this period, the cumulative number of moths trapped under the lights of the rice leaf roller in southern rice areas was 71,000, and the average number of moths trapped by a single light per day was 18.5. from the end of july to the beginning of august, the average weekly cumulative number of insect traps in each province increased by 1.5-2.5 times month-on-month. zhejiang, shanghai, and jiangsu were 610, 206, and 500 insects, an increase of 6.7 times, 4.9 times, and 16.6 times month-on-month. , hunan yuanjiang, zhejiang yuhang, jiangsu yixing up to 4000-5000 heads. in early and late august, the number of worms in the south of the yangtze river and the lower reaches of the yangtze river declined, with 200-250 in the south of the yangtze river and 350-450 in the lower reaches of the yangtze river, but the average increase in southern china was 1.1-3.8 times. among them, zhejiang anji, jiangsu yixing, there are 300-500 moth peaks in a single day in daoxian county, hunan province.
at present, the main rice-producing areas in the south, such as the south of the yangtze river and the middle and lower reaches of the yangtze river, are in their peak occurrence period. among them, hunan and jiangsu currently occur in an area of 41.41 million mu, accounting for 63.7% of the national total. through timely prevention and control, the occurrence degree in the field has been effectively controlled. the average number of larvae per mu in hunan, guangdong and shanghai is 3000-8000, and the rest are generally less than 1000.
(3) epidemic diseases
at present, rice blast is generally light, with a cumulative area of 20.62 million mu. after control, the rate of diseased leaves in the field is 3%-7% in southwest china, and the rate of diseased ears is 1%-4%. in other areas, the rate of diseased leaves is generally below 3% and the rate of diseased ears is below 1.5%.
the black-streaked dwarf disease of rice in southern china is currently mild to mild, with a cumulative incidence of 310,000 mu. however, the local mediator virus-carrying rate in guangxi is relatively high, and there have been concentrated outbreaks in the fields. after testing, the virus-carrying rates of white-backed planthoppers in pubei and yizhou in late july were 5% and 2%, the highest since 2012. according to an expert survey at the end of july and the beginning of august, the incidence rate of about 5,000 mu of fields in guangxi nanning and guilin is 1%-3%, and the incidence of 500 mu of fields is 5%. the incidence of early rice in the heading and flowering stage is generally 5%. -20%, with serious fields reaching 35%.
second, the trend of the next stage
according to the forecast of the national meteorological center, in mid-to-late august, the temperature in most of my country's main rice-producing areas will be close to the same period of the year to relatively high, and there will be more precipitation in the central and southern parts of northeast china, most of north china, and jianghuai. there is continuous heavy rainfall in the lower reaches and the jiangnan rice area. in late august, 1-2 typhoons may be generated and move northward. the meteorological conditions are favorable for the northward migration and tossing of rice pests, and the spread of rice blast and bacterial diseases. popularity. it is expected that in the next stage, the rice planthopper will occur more heavily in the middle and lower reaches of the yangtze river and the jiangnan rice areas, and moderately in other rice areas in the south; the overall incidence is moderate, but the epidemic hazards of panicle blast and branch blast in the northeast and lower reaches of the yangtze river should be guarded against; the southern rice black-streaked dwarf disease has a heavy epidemic risk in the guangdong and guangxi regions, and the late-planting medium and late rice production areas should strengthen tillering and pulling pre-holiday virus disease monitoring to guard against yield loss; in addition, in areas affected by typhoons, pay close attention to the occurrence and development of bacterial blight, bacterial leaf spot and other diseases, and prepare for emergency prevention and control.
(information source: official website of the national agricultural technology extension service center)