The National Agricultural Technology Center has released the latest update on the occurrence of diseases and pests in early rice.

Currently, early rice in southern South China is at the young panicle differentiation stage, while in northern South China, the Jiangnan region, and the middle reaches of the Yangtze River, it is in the tillering stage; in the Southwest, single-season rice is in the regreening–tillering stage. According to monitoring across various localities, in May, brown planthoppers have entered large numbers in the Jiangnan and southern Southwest rice-growing areas; stem borers have attracted high moth counts in northern Southwest and localized parts of the Jiangnan region; and two-brooded stem borers are present at high densities and causing more severe damage than during the same period last year in northern South China and the Jiangnan rice-growing areas. Sheath blight and blast are spreading rapidly in southern rice-producing regions. Nationwide, the cumulative area affected by rice diseases and pests has reached 61.54 million mu‑times, a 9% increase year on year. In the next phase, significant rainfall is expected in South China and the Jiangnan region, with weather conditions further conducive to the occurrence and development of rice diseases and pests. Local authorities should remain vigilant, closely monitor field dynamics, issue timely pest and disease advisories, and provide appropriate guidance to farmers for effective control measures.
　　1 Rice planthopper
　　Brown planthoppers have cumulatively infested 10.34 million mu across the rice-growing regions of South China, Southwest China, and the Jiangnan area—3.6 times the level of the previous two weeks, up 3.5% year on year. According to monitoring at 280 regional stations nationwide, since May, the primary influx of brown planthoppers has been concentrated in South China, the southern part of Southwest China, and the Jiangnan rice‑growing areas. In particular, the northwestern part of South China, the southern part of Southwest China, and the western Jiangnan region have recorded peak migration events with over 1,000 insects per trap per day. Statistics show that total migration volume in May declined by 33.6% compared with the same period last year; however, the Jiangnan and southern Southwest regions continue to experience relatively high influxes, with Zhejiang, Hunan, Hubei, and Yunnan reporting totals 2 to 4 times those of the corresponding period last year. Field populations have risen markedly compared with the previous two weeks: in South China and the southern Southwest, densities generally range from 150 to 750 insects per 100 tillers, while in certain fields along the Guangxi coast and in southeastern Guangxi, as well as in southeastern Yunnan, they can reach 1,000 to 2,500 insects per 100 tillers. In the Jiangnan region, densities typically fall between 20 and 250 insects per 100 tillers, with some localized areas recording as high as 300 to 500 insects per 100 tillers.
　　2 Rice leafroller
　　The rice leafroller has cumulatively infested 5.39 million mu‑times across the rice-growing regions of South China, Southwest China, and the Jiangnan area—3.4 times the level of the previous two weeks and up 2.9% year on year. In mid-May, minor immigration peaks were detected along the coasts and in central Guangxi, southern Hunan, and parts of western Guangdong. According to data from 280 monitoring stations under the National Rice Pest and Disease Surveillance Network, total moth catches at light traps in May declined by 40.7% compared with the same period last year. However, moth counts remained relatively high in northern Southwest China and localized areas of Jiangnan; for example, in Sichuan, Hunan, and Zhejiang, trap catches were 2 to 3.5 times those of the corresponding period last year. Field pest populations were generally low: in South China, adult moth densities averaged 100–450 per mu, with localized peaks of 900–3,000 per mu in southern Guangxi and western Guangdong; larval densities ranged from 300 to 1,000 per mu, with some coastal areas in Guangxi reporting as many as 10,000–20,000 per mu. In the Jiangnan region, adult moth densities typically stood at 5–40 per mu, with higher levels of 100–200 per mu, while larval densities averaged 200–650 per mu, reaching as high as 1,056 per mu in Yongzhou, Hunan. Field damage from leaf rolling was mild, with early‑season rice showing leaf‑rolling rates below 2% in most cases.
　　3 Rice stem borer
　　The rice stem borer has cumulatively infested 33.61 million mu‑times across the South China, Southwest, Jiangnan, and middle Yangtze River rice‑growing regions, an 8.2% year-on-year increase—double the level of the previous two weeks. According to data from 297 regional monitoring stations nationwide, as of May 30, the total number of moths trapped by light traps had risen 27.9% compared with the same period last year. In Zhejiang and Hunan, moth catches were 2.3 and 2.1 times those of the corresponding period last year, respectively, while Guangdong, Guangxi, Sichuan, and Shanghai saw increases of 30% to 60%. In northern South China and the Jiangnan rice‑growing areas, field populations of the rice stem borer remain high, with larval densities typically ranging from 500 to 4,500 per mu, and in some cases reaching 6,000 to 8,000. In localized fields in Fujian and Hubei, densities have soared as high as 20,000 larvae per mu. Damage in the fields is more severe than during the same period last year: in most of the Jiangnan region, the percentage of tillers with dead sheaths ranges from 13% to 48%, the percentage of dead‑sheath plants from 1% to 9%, and the percentage of dead hearts from 0.1% to 0.6%; in certain severely affected fields in Hubei, the dead‑sheath rate has reached as high as 90%.
　　4 Sheath Blight
　　Blast disease has affected a cumulative area of 9.58 million mu across the rice-growing regions of South China, Southwest China, the Jiangnan region, and the middle reaches of the Yangtze River—5.2 times the figure from the previous two weeks and 30.4% higher than the same period last year. At present, blast is advancing rapidly in the early‑rice areas of southern China, with infection rates generally ranging from 0.5% to 7.5%; in parts of southern Guangxi, local rates are considerably higher, at 23% to 52%, and in some fields in southeastern Guangxi, they have soared as high as 92%.
　　5 Rice Blast Disease
　　Rice blast has cumulatively affected 1.63 million mu across the rice-growing regions of South China, Southwest China, the Jiangnan area, and the middle reaches of the Yangtze River—four times the level of the previous two weeks—but remains down 22% year on year. At present, the average disease‑infested leaf rate in early‑season rice is generally 0.5% to 2%, with higher rates ranging from 3% to 5%; in some localized fields in Fujian, it has peaked at 23.7%, and a few plots have even experienced “stem‑base blight” caused by leaf blast.
　　6 Future Trends and Recommendations
　　According to forecasts from the China Meteorological Administration, over the next 10 days, South China and the rice-growing regions of Jiangnan will experience heavy rainfall, with precipitation in central and eastern South China and eastern and southern Jiangnan expected to exceed normal levels by 30% to 70%. During the subsequent 11–20 days, eastern Jiangnan and parts of South China will see periods of rain, which will facilitate the immigration and reproduction of “two‑migration” pests and the onset of diseases such as sheath blight and rice blast, while simultaneously posing challenges to rice pest and disease management. All localities are urged to strengthen monitoring, maintain a comprehensive grasp of pest and disease dynamics, issue timely and accurate pest and disease advisories, and ensure effective guidance for prevention and control efforts.