At present, the single-cropping rice in South China and Jiangnan and the southwest and northeast are in the filling to milk maturity stage, the late rice in South China and Jiangnan is in the tillering to pregnant panicle stage, and the single-cropping rice in the middle and lower reaches of the Yangtze River is in the stage of breaking the mouth and pumping ears. Rice diseases and insects were generally mild to moderate, of which dimodium borer and striated blight were moderately occurring, rice planthoppers and rice longitudinal leaf borers were mild to moderate, and rice blast disease was mild.
In the next stage, there is more rainfall in the eastern part of Jiangnan, South China and Southwest China, which is conducive to the return and landing of "two migration" pests and the prevalence of rice diseases and insect pests; adult rice longitudinal leaf borers in the middle and lower reaches of the Yangtze River will lay eggs in large quantities, and the amount of larvae in the field will increase rapidly.
Rice planthopper
Rice planthopper occurs in the southern rice area of mild to moderate, and the current occurrence area is 86.23 million mu, a year-on-year decrease of 5.7%. Recently, there has been no obvious peak of insect attraction in the southern rice area, according to the monitoring statistics of 275 rice planthopper detection and reporting regional stations across the country, the total number of insects under the lights in August decreased by 62.2% year-on-year. According to local monitoring, the amount of rice planthoppers in the single-cropping rice areas of South China, Jiangnan and Southwest China is generally 450-900 heads, the high is 1000-2500 heads, and the local fields in southeastern Yunnan, southeastern Guizhou and southeastern Qiong are more than 10,000. The number of late rice planthoppers in South China and Jiangnan is generally 100-500 heads, the high is 700-1600 heads, and the local fields in western Guangdong, southeastern Guizhou and southern Fujian are as high as 2000-4000 heads. Rice planthoppers in the middle and lower reaches of the Yangtze River are generally less than 300 and 400-600 heads high. Compared with the same period last year, the amount of insects in the field was generally low and locally high, and Hainan, Guangxi, Sichuan and Jiangxi were 14%-31% higher than the same period last year.
Rice longitudinal curl leaf borer
Rice longitudinal leaf borer is generally mild to moderate in the southern rice area, and the current occurrence area is 74.39 million mu, a year-on-year decrease of 14.3%. In late August, the peak of the sixth (4) generation moths of rice longitudinal leaf borer was monitored in the rice areas of the middle and lower reaches of the Yangtze River, of which the number of moths per mu in Jiangsu along Taihu Lake and along the river was 1000-4500 heads; the number of moths per mu in the rice areas of South China and Jiangnan was generally 50-400 heads, and the high moths were 500-1100 heads. The amount of larvae in the field has increased compared with the previous period, and the number of larvae per mu in the rice areas of South China and Jiangnan is generally 1000-7000 heads, and the high is 10,000-30,000 heads; the amount of larvae per mu in the middle and lower reaches of the Yangtze River is generally 100-600 heads, and the amount of eggs per mu is generally 2000-10000 grains, and the local areas along the Taihu Lake and along the river in Jiangsu exceed the large occurrence index. The degree of damage in the field is generally mild, and the leaf roll rate is generally less than 4%, and the local field plot in Hubei Ishui is as high as 49%.
Chilo
The overall occurrence of the second chemical borer in Jiangnan, southwest, middle and lower reaches of the Yangtze River and Jianghuai rice area is moderate, and the current occurrence area is 63.2 million mu, an increase of 9.7% year-on-year. Among them, the occurrence of rice areas in Jiangnan is relatively prominent, the amount of larvae per mu is generally 100-600 heads, the high is 1000-5000 heads, and the local field plots in Leiyang, Hunan are as high as 12,000 heads. The rate of dry sheath bushes caused by field damage is generally 4%-16%, the local rate of Xingan in Jiangxi is as high as 64%, the dry heart rate is generally 0.1%-0.8%, and the local rate in Suixian County, Hubei is as high as 16%.
Striated blight
Striated blight occurs moderately in the main rice-producing areas, with a current incidence of 108 million mu, close to the same period last year. The disease spread rapidly in the late rice areas of South China, Jiangnan late rice and the middle and lower reaches of the Yangtze River, with the disease rate generally being 1%-8%, the high rate being 10%-20%, and the local rate of Ji'an in Jiangxi being as high as 98%; the disease cluster rate is generally 10%-35%, the high rate is 40%-50%, and the highest is 100% in Huangpi, Hubei.
Rice blast
The overall occurrence of rice blast is mild, and the current occurrence area is 15.16 million mu, a year-on-year decrease of 10.0%. The leaf rate of rice blast in the single-cropping rice areas of South China and Jiangnan and southwest and northeast china is generally 0.1%-6%, and the high rate is 8%-20%, and the ear disease rate is generally 0.3%-1.3%, and the high rate is 2%-5%. The leaf rate of rice blast disease in the late rice areas of South China, Jiangnan late rice and the middle and lower reaches of the Yangtze River is generally less than 3%, and the local field plot in Hong'an, Hubei Province is as high as 52.5%.
Future trends and recommendations
According to the forecast of the National Meteorological Center, in the coming week, due to the influence of low-pressure circulation and monsoon wind and cloud system, the rainfall in the eastern part of Jiangnan, South China and Southwest China will be 30-60% more than the same period of the year, which is conducive to the return and landing of "two migration" pests, and the weather conditions of moderate temperature and high humidity are conducive to the occurrence and epidemic of rice diseases and insect pests in the region. In addition, the amount of rice longitudinal leaf borer moth in the middle and lower reaches of the Yangtze River rice area is large, and the number of larvae in the field will increase rapidly with the large number of adult eggs laid and the hatching of eggs. All localities need to strengthen monitoring, fully grasp the dynamics of diseases and insects, timely and accurately release information on diseases and insects, and effectively do a good job in prevention and control guidance.
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Source: National Agricultural Technology Extension Center
Editor of this issue: Jiang Jiang