Currently, rice diseases and pests are generally at low to moderate levels; rainfall in the eastern regions will favor the return of “two‑migration” pests.

　　At present, mid-season rice in South China and the Jiangnan region, as well as single-cropping rice in Southwest and Northeast China, are in the grain-filling to milky-ripe stage; late-season rice in South China and the Jiangnan region is at the tillering to booting stage; and single-cropping rice in the middle and lower reaches of the Yangtze River is at the heading–spike‑emergence stage. Overall, rice diseases and pests are expected to be mild to moderate, with the stem borer and sheath blight occurring at a moderate level, brown planthopper and rice leafroller at a mild to moderate level, and blast disease at a mild level. In the next phase, above‑average rainfall in the Jiangnan, South China, and eastern parts of Southwest China will favor the return and settlement of migratory pests, as well as the occurrence and spread of rice diseases and pests; meanwhile, in the rice-growing areas of the middle and lower Yangtze River, adult rice leafrollers will lay large numbers of eggs, leading to a rapid increase in larval populations in the fields.
　　Rice pest infestation
　　Rice planthopper
　　Brown planthoppers are occurring at light to moderate levels in southern rice-growing regions, with a current affected area of 86.23 million mu‑times, down 5.7% year on year. Recently, no distinct peak in trap catches has been observed across southern rice areas; according to monitoring data from 275 national brown planthopper surveillance stations, total trap catches in August were 62.2% lower than the same period last year. Local surveys indicate that in South China and the middle‑season rice areas of Jiangnan, as well as in the single‑crop rice regions of Southwest China, the average number of planthoppers per 100 plants ranges from 450 to 900, with higher counts reaching 1,000 to 2,500; in localized fields in southeastern Yunnan, southeastern Guangxi, and southeastern Hainan, densities exceed 10,000 per 100 plants. In late‑season rice areas of South China and Jiangnan, the average density is typically 100 to 500 per 100 plants, with peaks of 700 to 1,600; in certain fields in western Guangdong, southeastern Guangxi, and southern Fujian, densities can soar to 2,000 to 4,000 per 100 plants. In the single‑crop rice regions of the middle and lower Yangtze River basin, densities generally remain below 300 per 100 plants, with higher counts ranging from 400 to 600. Compared with the same period last year, overall field populations are lower, though locally they remain elevated; in Hainan, Guangxi, Sichuan, and Jiangxi, year‑on‑year increases range from 14% to 31%.
　　Rice leafroller
　　In the southern rice-growing regions, the rice leafroller has generally been at a light to moderate level of occurrence. To date, the affected area totals 74.39 million mu‑times, down 14.3% year on year. In late August, peak populations of the sixth generation of adult rice leafrollers were recorded in the middle and lower reaches of the Yangtze River; in Jiangsu’s areas along Lake Tai and along the river, moth densities ranged from 1,000 to 4,500 per mu. In South China and the Jiangnan rice region, typical moth densities were 50–400 per mu, with higher counts reaching 500–1,100 per mu. Field larval populations have increased compared with earlier stages: in South China and Jiangnan, typical larval densities were 1,000–7,000 per mu, with peaks of 10,000–30,000 per mu; in the middle and lower Yangtze River region, larval densities averaged 100–600 per mu, while egg counts generally ranged from 2,000 to 10,000 per mu, with some localized areas along Lake Tai and along the river in Jiangsu exceeding the threshold for severe outbreaks. Overall, field damage remains relatively mild, with leaf‑rolling rates typically below 4%, though in certain fields in Xishui, Hubei, they reached as high as 49%.
　　Two-brooded stem borer
　　The rice stem borer is generally at moderate levels of occurrence across the Jiangnan, Southwest, middle and lower reaches of the Yangtze River, and the Jianghuai rice-growing regions. To date, it has affected 63.2 million mu‑times, a 9.7% increase year on year. Among these areas, the Jiangnan rice region stands out, with larval densities typically ranging from 100 to 600 per mu, and in some cases reaching 1,000 to 5,000; in localized fields in Leiyang, Hunan, densities have soared as high as 12,000 larvae per mu. Field damage has resulted in a typical rate of dead‑sheath clusters of 4% to 16%, with localized peaks of 64% in Xingan, Jiangxi; dead‑heart rates generally range from 0.1% to 0.8%, but in certain areas of Suixian, Hubei, they have reached as high as 16%.
　　Rice diseases
　　Sheath blight
　　Sheath blight is occurring at moderate levels in major rice-producing regions, with an affected area of 108 million mu, roughly on par with the same period last year. In South China and the Jiangnan late‑rice growing areas, as well as in the single‑cropping rice zones of the middle and lower reaches of the Yangtze River, the disease has been spreading rapidly. The incidence of infected plants generally ranges from 1% to 8%, with some localized outbreaks reaching 10% to 20%; in Ji’an, Jiangxi, it has even soared to 98%. The proportion of infected tillers typically stands between 10% and 35%, with higher rates of 40% to 50%, and in Huangpi, Hubei, it has peaked at 100%.
　　Rice blast disease
　　Rice blast has been generally mild, with a current affected area of 15.16 million mu‑times, down 10.0% year on year. In South China and the middle rice‑growing regions of Jiangnan, as well as in the single‑crop rice areas of Southwest and Northeast China, the leaf‑infection rate typically ranges from 0.1% to 6%, with higher rates of 8% to 20%; the panicle‑infection rate is usually between 0.3% and 1.3%, reaching 2% to 5% in some cases. In South China and Jiangnan’s late‑rice areas, and in the middle and lower reaches of the Yangtze River’s single‑crop rice zones, the leaf‑infection rate is generally below 3%, though in localized fields in Hong’an, Hubei, it has reached as high as 52.5%.
　　According to forecasts from the National Meteorological Center, over the next 10 days, influenced by a low-pressure circulation and monsoon cloud systems, the regions of Jiangnan, South China, and eastern Southwest China are expected to experience rainfall 30% to 60% above normal for this time of year. This favorable weather pattern will promote the return and settlement of “two‑migration” pests, while warm, humid conditions will also facilitate the occurrence and spread of rice diseases and pests in these areas. In addition, the middle and lower reaches of the Yangtze River—key rice‑growing regions—are seeing high adult populations of the rice leafroller; as adults lay large numbers of eggs and the eggs hatch, larval densities in the fields will increase rapidly. All localities are urged to strengthen monitoring, maintain a comprehensive understanding of pest and disease dynamics, issue timely and accurate pest‑and‑disease advisories, and implement effective guidance on prevention and control measures.

Source: Pest and Disease Information