Dynamics of Major Diseases and Pests in Middle and Late Rice

Time:

2016-08-25


South China, Southwest, Jiangnan middle rice, and Northeast single season rice are in the stage of full panicle to milky maturity, while South China, Jiangnan, and the middle and lower reaches of the Yangtze River late rice are in the stage of tillering to jointing, and Jianghuai single season late rice is in the stage of jointing to booting. The short winged adult of rice planthopper has a rapid increase in field pest numbers in the late rice areas of South China, Jiangnan, and the middle and lower reaches of the Yangtze River, posing a significant threat of recurrence; The rice leaf roller has severe overlapping generations in the late rice areas of Jiangnan and the middle and lower reaches of the Yangtze River, showing an aggravating trend of occurrence; Rice blast disease is spreading rapidly in the late rice areas of Southwest China, South China, and Jiangnan, and poses a significant threat to its recurrence in the later stages.

1、 Migratory pest

The occurrence of rice planthopper is generally moderate and partially severe in the rice areas of Southwest, South China, Jiangnan, and the middle and lower reaches of the Yangtze River, with a cumulative area of 187 million acres, a year-on-year decrease of 0.7%. As of August 16th, the number of rice planthoppers under light in most rice areas is relatively low, with a single day larvae count of less than 500 per light. Only in Shaowu and Jian'ou, Fujian, and Chenxi, Hunan, there were over a thousand migratory bees with a single lamp on the same day. The amount of pests in the field remains stable, and there are more serious occurrences of missed prevention fields in some areas. Southwest single season rice, rice planthoppers in rice fields in southern China, Jiangnan, and the middle and lower reaches of the Yangtze River have a low population of 100-700 and a high population of 800-1000. In Fuling, Chongqing, and Yicheng, Hubei, there are over 5000 missing control plots of rice planthoppers. In the late rice fields of southern China, Jiangnan, and the middle and lower reaches of the Yangtze River, the number of hundred cluster insects is generally 100-500, with a higher number of 800-1000, and a higher number of short winged insects. Compared with the same period last year, the field pest levels in the Southwest rice region and the Jianghuai rice region increased by 39% and 37%, respectively, while in the South China, Jiangnan, and the middle and lower reaches of the Yangtze River rice regions, they decreased by 26.6%, 23.1%, and 39.7%, respectively.

The occurrence of rice leaf roller is generally moderate in the rice regions of Southwest, South China, Jiangnan, and the middle and lower reaches of the Yangtze River. Among them, the occurrence is more severe in the eastern part of Southwest and some areas in the western part of Jiangnan, with a cumulative occurrence area of 121 million mu, a year-on-year decrease of 9%. According to local monitoring, the number of moths and larvae in rice fields in the southwest, southern China, and Jiangnan rice regions is significantly low, with a general population of 20-300 moths per mu and a high of 400-1000 moths, with over 2000 moths in some areas; The average number of larvae per mu is 100-700, with a height of 900-2000. In the late rice fields of Jiangnan and the middle and lower reaches of the Yangtze River, moths, eggs, and larvae coexist, with severe generational overlap. The number of moths per mu is generally 40-350, ranging from 400-700 to 800-3000, and the number of larvae per mu is generally 4000-7000. After effective prevention and control, the leaf rolling rate is mostly controlled at 1% -4%. Compared with the same period last year, the number of pests in the fields in the rice fields of Jiangnan and the middle and lower reaches of the Yangtze River increased by 20.3% and 208%, respectively; The rice areas in South China and Jianghuai decreased by 31% and 45.6% respectively.

2、 Epidemic diseases

The occurrence of rice blast is generally moderate in the rice regions of South China, Jiangnan, and the middle and lower reaches of the Yangtze River, while it is partially severe in the southwest rice region. The cumulative occurrence area is 30643200 acres, an increase of 9.4% year-on-year. The rate of diseased leaves in the rice fields of southern China, Jiangnan, and the middle and lower reaches of the Yangtze River is generally between 0.1% and 4.2%, while the rate of diseased leaves in the partially leaked fields of central Guangxi is as high as 80%, and the rate of diseased panicles is generally between 0.2% and 2%; The rate of diseased leaves in late rice is generally 0.2% -3.1%, with a high rate of 5.2% -9.6%. The general diseased leaf rate of single season rice in the southwest rice region is 8.64%, and locally severe fields in Hechuan, Chongqing are as high as 96%; The general diseased ear rate is 5.86%, and in some severe fields in Hechuan, it is as high as 98%.

3、 Frequent pests and diseases

The occurrence of Chilo suppressalis is generally moderate in the southwest, Jiangnan, and the middle and lower reaches of the Yangtze River, with a cumulative area of 130 million acres, an increase of 2.1% year-on-year. Currently, the rice borer, Chilo suppressalis, has entered a peak period of three generations of damage in the rice fields of Jiangnan and the middle and lower reaches of the Yangtze River. The average number of larvae per mu in the field is 143-1000, while in Hengyang, Hunan and Loudi, there are over 4000. After effective prevention and control, the dry heart rate of paddy fields is generally maintained at 0.1% -2%, while the dry heart rate of local areas in Laifeng, Hubei and northern Chongqing is as high as 25%; The withered sheath rate of late rice fields is generally 3% -5%, and the withered sheath rate of leakage prevention fields in Wan'an, Jiangxi exceeds 25%.

The occurrence of sheath blight is generally severe in the rice areas of Jiangnan and the middle and lower reaches of the Yangtze River, with a significant upward trend. The cumulative occurrence area is 164 million acres, a year-on-year decrease of 5.9%. The condition of rice in southern China and Jiangnan rice regions is basically stable, with disease cluster rates generally ranging from 10% to 35%, with high rates ranging from 45% to 80%; Jiangxi Lianhua, Wuning, and Hubei Xinzhou have 100% leakage prevention fields. The late rice region is in a horizontal epidemic period, with disease cluster rates generally ranging from 1% to 20%, with high rates ranging from 25% to 36%. The leakage prevention rate in the Hukou area of Jiangxi Province is as high as 56%.

4、 Future trends

According to the forecast of the Central Meteorological Observatory, in the next 10 days, there will be continuous light to moderate rain in the eastern part of Southwest China, South China, Northeast China, and other regions, with some areas experiencing heavy rain, which is more conducive to the occurrence and development of rice diseases and pests; In addition, in the next 10 days, there will be 1-2 typhoons generated in the South China Sea, which may affect the southern region of China and facilitate the expansion and spread of late rice pests and rice blast. Please attach great importance to plant protection institutions at all levels, adhere to the principle of "not getting autumn crops in one day, not relaxing monitoring work in one day", conscientiously implement the monitoring and investigation system, strengthen monitoring and early warning, implement classified guidance, and improve the effectiveness of prevention and control.

Source: Disease and Pest Monitoring and Reporting Office of the National Agricultural Technology Promotion Center