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    It is projected that major rice diseases and pests will occur at moderate to severe levels overall, affecting a total area of 916 million mu‑times.


    Release Date:

    2019-07-16

    On July 11–12, the National Agricultural Technology Extension Center convened a consultation meeting in Suzhou, Jiangsu, to discuss the trends in the occurrence of diseases and pests affecting mid- and late-season rice. Based on a comprehensive analysis of current pest and disease populations, cultivation practices, and climatic factors, technical personnel from plant protection agencies in 20 major rice-producing provinces, autonomous regions, and municipalities directly under the central government, along with relevant experts, forecast that the major diseases and pests of mid- and late-season rice will generally occur at moderate to severe levels (rating 3–4), affecting a total area of 916 million mu‑times. Specifically, brown planthopper and sheath blight are expected to occur at severe levels (rating 4), while stem borer, two-brooded stem borer, blast, and false smut are projected to occur at moderate levels (rating 3). The three-brooded stem borer and southern rice black-streaked dwarf disease are anticipated to occur at light to slightly light levels.

    On July 11–12, the National Agricultural Technology Extension Center convened a consultation meeting in Suzhou, Jiangsu, to discuss the forecast for the incidence trends of diseases and pests in mid- and late-season rice. Based on a comprehensive analysis of current pest and disease populations, cultivation practices, and climatic factors, technical personnel from plant protection agencies in 20 major rice-producing provinces, autonomous regions, and municipalities directly under the central government, along with relevant experts, projected that the overall severity of major rice diseases and pests will range from moderate to relatively severe (levels 3–4), affecting a total area of 916 million mu‑times. Specifically, brown planthopper and sheath blight are expected to occur at a relatively severe level (level 4), while stem borer, two-brooded stem borer, blast, and false smut are anticipated to occur at a moderate level (level 3). The three-brooded stem borer and southern rice black-streaked dwarf disease are expected to occur at a mild to slightly mild level (levels 1–2).

     
    I. Overview of Early Rice and Single-Cropping Medium-Ripening Rice Pest and Disease Incidence in the Early Growth Stages
     
    In the first half of this year, major rice pests and diseases occurred at moderate to severe levels (levels 3–4) across the main production areas, affecting a total area of 336 million mu‑times, a 6.2% decrease compared with the same period last year. Among these, pest outbreaks covered 260 million mu‑times, down 2.3% year on year, while disease outbreaks affected 75.76 million mu‑times, a 17.4% decline from the previous year. The key characteristics of these outbreaks are as follows:
     
    Stink bugs have generally been at moderate to severe levels (levels 3–4), more severe than last year. Specifically, the South China rice region has experienced severe infestations (level 4); the Jiangnan and southern Southwest regions have seen moderate outbreaks (level 3); while the northern Southwest and the middle‑and‑lower reaches of the Yangtze River have reported relatively mild occurrences (level 2). The cumulative affected area nationwide stands at 92.75 million mu, slightly higher than last year. According to monitoring across various localities, this year’s stink bug migration began about 20 days earlier than in the previous year, with peak migration events close to the long-term average, though overall migrant populations remain elevated. As of July 5, data from 294 rice pest‑monitoring stations under the National Crop Pest and Disease Forecasting Network show that total stink bug arrivals are 2.3 times those of the same period last year and 4.5% above the five‑year average. Among these, whitebacked planthoppers and brown planthoppers have arrived at 2.5 and 1.6 times last year’s levels, respectively, up 1.8% and 18.2% compared with the five‑year average; the proportion of brown planthoppers is notably higher than usual. Looking at provincial trends, Fujian, Hainan, and Jiangxi have recorded arrival totals 7–11 times those of the same period last year, while Guangxi, Guizhou, Hunan, and Zhejiang have seen totals 2–5 times higher. Field populations are significantly above last year’s levels. In early‑season rice areas of South China and Jiangnan, initial densities were low but rose rapidly during the mid‑season, leading to severe outbreaks; by the later stages, timely control measures brought field populations in most regions back below threshold levels. However, some poorly managed fields still harbor high pest densities, and in certain locales of Guangxi, Guangdong, and other provinces, localized “breakthrough” infestations have occurred.
     
    The rice leafroller has generally been at a moderate level of occurrence (Level 3), higher than last year. Specifically, it is severe in western South China (Level 4), moderately prevalent in eastern South China, the Jiangnan region, and the southwestern rice‑growing areas (Level 3), and slightly infested in the middle and lower reaches of the Yangtze River basin (Level 2). The cumulative affected area nationwide stands at 52.67 million mu, up 21.6% year on year. According to monitoring across various regions, this year’s migration period for the rice leafroller began about 10 days earlier than last year, with significantly higher moth influxes. As of July 5, data from 294 rice pest‑and‑disease monitoring stations under the National Crop Pest and Disease Forecasting Network show that total migrant moths are 2.5 times those of the same period last year and 2.2 times the average of the past five years. By province, Zhejiang, Hainan, Jiangxi, and Anhui have seen influxes 5–10 times greater than last year, while Guangdong, Guangxi, Fujian, and Hunan report 2–3 times the previous year’s levels. Field larval populations exceed last year’s figures, and leaf‑rolling damage is more severe than in 2022, with typical leaf‑rolling rates ranging from 0.5% to 7%, and in some cases reaching 15%–25%. In severely affected fields in Fuqing and Gutian in Fujian, as well as in Yangchun and Xinxing in Guangdong, these rates have soared to 40%–70%.
     
    The rice stem borer is generally at a moderate level of occurrence (Level 3), with heavier infestations (Level 4) in the rice-growing regions of southern Jiangnan, unchanged from the previous year. The cumulative affected area nationwide stands at 77.85 million mu‑times, down 11.3% year on year. According to monitoring data from 294 rice‑crop pest‑and‑disease surveillance stations under the National Pest and Disease Forecasting Network, as of July 5, the total number of moths trapped by light traps was 21.0% lower than the same period last year. By province, Jiangxi and Hunan recorded increases of 10.1% and 4.7%, respectively, while moth catches in all other provinces declined to varying degrees. For the first generation of the rice stem borer, the incidence of dead‑sheath plants typically ranges from 1% to 5%, with higher rates reaching 10% to 15%; the incidence of dead‑heart plants generally falls between 0.5% and 3%, peaking at 4% to 7%, with some uncontrolled fields in southern Jiangxi reporting as high as 65.9%.
     
    Overall, sheath blight occurred at moderate to severe levels (rating 3–4), less severely than the previous year. Specifically, the South China rice region experienced severe outbreaks (rating 4); the Southwest, Jiangnan, and the middle reaches of the Yangtze River rice regions saw moderate outbreaks (rating 3), with localized areas reporting severe outbreaks (rating 4); while the lower Yangtze and the Jianghuai rice regions recorded mild to slightly mild outbreaks (ratings 1–2). The cumulative affected area nationwide totaled 54.34 million mu, a decrease of 16.2% compared with the same period last year. In the early‑rice growing areas of South China and Jiangnan, the epidemic peak occurred around late May, similar to last year, after which the affected area expanded rapidly and disease severity continued to increase. By the end of June, preliminary surveys indicated that the incidence of infected tillers generally ranged from 15% to 30%, with some fields reaching as high as 35% to 60%.
     
    Rice blast incidence was generally mild (level 2), with localized areas experiencing moderate to severe outbreaks (level 4), lower than the previous year. The cumulative affected area nationwide totaled 9.82 million mu, a 10.9% decrease compared with the same period last year. In particular, in the rice-growing regions of South China, Southwest China, and eastern Jiangnan, susceptible varieties showed moderate to severe infections (level 4) in some localized areas, with field disease‑leaf rates typically ranging from 2% to 12%, and in severe cases reaching 30% to 70%. In Guangdong, Fujian, Jiangxi, and Sichuan, certain severely affected fields exhibited “root‑bound” symptoms. Field disease‑panicle rates were generally between 0.5% and 2%, with higher incidences of 15% to 20%; in central Guangxi and eastern Jiangxi, isolated plots recorded rates as high as 90%.
     
    Southern rice black-streaked dwarf disease has occurred at a low level (Level 1) in the rice-growing regions of South China and the Jiangnan area, with the incidence rate generally below 1.2%. The cumulative affected area nationwide is 157,000 mu, a year-on-year decrease of 41.9%.
     
    II. Forecast of the Occurrence Trends of Diseases and Pests in Mid- and Late-Season Rice           
     
    (1) Rice Pests
     
    Brown planthopper infestations were severe (Level 4), more intense than last year, affecting 279 million mu‑times; the area requiring control measures was 203 million mu‑times, accounting for 72.8% of the total affected area. Specifically, the whitebacked planthopper was moderately prevalent (Level 3) in southern rice-growing regions, while the brown planthopper was severely prevalent (Level 4) in South China, the Jiangnan region, eastern Southwest China, and the middle and lower reaches of the Yangtze River, and moderately prevalent (Level 3) in the Jianghuai rice‑growing area.
     
    The rice leafroller is at a moderate level of occurrence (Level 3), with localized areas experiencing heavier infestations (Level 4), exceeding last year’s levels. The total affected area amounts to 165 million mu‑times, with 140 million mu‑times requiring control measures, accounting for 84.8% of the total affected area. Specifically, eastern South China, eastern Jiangnan, eastern Southwest China, and the middle and lower reaches of the Yangtze River rice-growing region are experiencing heavier infestations (Level 4), while central and western South China, western Jiangnan, and the northwestern part of Southwest China are seeing moderate infestations (Level 3). Southern Southwest China and the Jianghuai rice-growing region are reporting lighter infestations (Level 2).
     
    The rice stem borer is expected to occur at a moderate level (Level 3), lighter than last year, with an affected area of 103 million mu‑times. The area requiring control measures is 98.3 million mu‑times, accounting for 95.4% of the total affected area. Specifically, the western Jiangnan region, the northern parts of Southwest China, and the middle reaches of the Yangtze River rice-growing areas are forecast to experience relatively severe outbreaks (Level 4), while the northern part of South China, eastern Jiangnan, the lower Yangtze River, the Jianghuai region, and the southern part of Northeast China are expected to see moderate outbreaks (Level 3). The southern parts of South China, the southern regions of Southwest China, and the northern parts of Northeast China are anticipated to have mild to slightly mild outbreaks (Levels 1–2).
     
    The rice stem borer is expected to occur at a mild level (Level 2), lighter than last year, affecting 7.0 million mu of farmland, with 3.77 million mu requiring control—accounting for 53.9% of the affected area. Specifically, the South China, Southwest China, and the middle reaches of the Yangtze River rice-growing regions are forecast to experience mild infestations (Level 2), while the Jiangnan and Jianghuai rice-growing areas are expected to see light infestations (Level 1).
     
    Other pests, including the rice stem borer, rice stem fly, and armyworm, have occurred to varying degrees in some rice-growing areas, affecting a total area of 52 million mu‑times.
     
    (II) Rice Diseases
     
    Sheath blight occurred at a severe level (Level 4), unchanged from the previous year, affecting 183 million mu of rice fields, with 185 million mu requiring preventive measures. Specifically, most of South China, the Jiangnan region, the northern parts of Southwest China, and the middle and lower reaches of the Yangtze River experienced severe outbreaks (Level 4); the Jianghuai and Northeast rice-growing areas saw moderate outbreaks (Level 3); and the southern part of Southwest China reported mild outbreaks (Level 2).
     
    Rice blast is at a moderate level (grade 3), more severe than last year, with an affected area of 56 million mu‑times and a preventive treatment requirement of 96.65 million mu‑times. Specifically, the Southwest, Jiangnan, the middle and lower reaches of the Yangtze River, the Jianghuai region, and the southern part of Northeast China experience moderate incidence (grade 3), while the South China and northern parts of Northeast China see relatively mild incidence (grade 2). However, in certain old‑infested areas and in regions where susceptible rice varieties are cultivated, localized outbreaks may reach a heavier level (grade 4).
     
    Rice false smut occurred at a moderate level (Level 3), unchanged from the previous year, affecting 44 million mu of land, with 69 million mu requiring preventive measures. Specifically, in the eastern Jiangnan region, the southwestern and northeastern parts, the middle and lower reaches of the Yangtze River, the Jianghuai area, and the southern part of Northeast China, the disease was at a moderate level (Level 3), with localized areas experiencing a heavier infestation (Level 4); in contrast, the western Jiangnan region and the northern part of Northeast China saw only a mild occurrence (Level 2).
     
    Southern rice black-streaked dwarf disease occurred at a mild to moderately mild level (grades 1–2) in South China, the southern part of Southwest China, the Jiangnan region, and the middle reaches of the Yangtze River rice‑growing areas, with localized outbreaks reaching a moderate level (grade 4). The incidence was lower than last year, affecting an area of 3 million mu.
     
    Other diseases, such as bacterial leaf blight and rice stripe disease, have occurred to varying degrees in some rice-growing regions, affecting a total area of 19 million mu.
     
    III. Main Basis for the Forecast
     
    (1) The initial pest and disease population meets or exceeds the threshold for moderate to severe outbreaks.
     
    At present, brown planthoppers are increasing rapidly in South China, the middle‑rice areas of the Yangtze River region, and the single‑cropping rice zones of Southwest China, with high population densities. The number of insects per 100 tillers generally ranges from 300 to 1,200, reaching as high as 2,000 to 5,000 in some cases; in Ziyuan County, Guangxi, this figure is 12.4 times that of the same period last year. In the middle and lower reaches of the Yangtze River, where single‑cropping rice is grown, the pest density stands at 30 to 200 insects per 100 tillers, with Hubei reporting a level twice that of the previous year. For the rice leafroller, the larval density per mu in South China, the middle‑rice areas of the Yangtze River region, and the single‑cropping rice zones of Southwest China is markedly higher than during the same period last year, typically ranging from 1,000 to 4,000 larvae, and in some instances reaching 10,000 to 30,000. In Fujian and Hunan, the larval count per mu is 1.5 times that of the corresponding period last year. In northern South China, northern Southwest China, and the rice‑growing areas of the Yangtze River region, the borer moth (Chilo suppressalis) infests fields at a rate of 300 to 1,500 larvae per mu. As for rice blast, outbreaks are widespread across southern rice‑growing regions, affecting numerous varieties; sheath blight has been persistently severe, with ample pathogen inoculum present in the fields.
     
    (II) Rice varieties and cultivation practices are generally favorable to the occurrence of diseases and pests.
     
    In the mid- and late‑season rice cropping systems, high‑quality varieties predominate; however, the major cultivars exhibit relatively low levels of disease resistance, with some showing reduced or lost resistance, thereby facilitating the spread of diseases such as blast and false smut. In particular, in the South China and Jiangnan rice regions, the extensive intercropping of single‑ and double‑cropped rice creates favorable conditions for the sequential damage caused by migratory rice pests and stem borers. Meanwhile, in the middle and lower reaches of the Yangtze River, the uneven maturity of single‑crop rice provides an ideal food source for migratory pests, while also increasing the likelihood that susceptible growth stages will coincide with prolonged periods of cloudy, rainy weather—both factors promoting the occurrence of rice diseases and insect pests. Furthermore, intensive cultivation practices involving high levels of water and fertilizer result in vigorous plant growth and dense canopy cover, fostering a microclimate characterized by warm temperatures and high humidity, which in turn enhances the incidence and severity of rice diseases and pests.
     
    (3) Meteorological conditions are generally favorable.
     
    According to forecasts from the National Climate Center, during this year’s peak summer months (July–August), two major rainy zones are expected across eastern China. The southern rainy zone will encompass eastern and southern South China, central and eastern Jiangnan, the middle and lower reaches of the Yangtze River, and southern Jianghuai; in southeastern South China and eastern Jiangnan, rainfall is projected to exceed normal levels by 20%–50%, creating favorable conditions for the proliferation of migratory rice pests and the spread of epidemic diseases in these rice-growing areas. The northern rainy zone will cover most of the rice‑growing regions in Northeast China, with southeastern Northeast China experiencing 20%–50% above‑normal precipitation, which will be conducive to the development of rice blast and false smut in that area. In September, warm temperatures and abundant rainfall in South China’s rice‑growing regions will further promote the occurrence and growth of migratory rice pests and rice blast. Moreover, during the second half of the year (July–December), 6–7 typhoons are expected to make landfall in China—close to or slightly above the long-term average—with a pattern of fewer storms early in the period and more toward the end, and overall stronger intensity. These systems are likely to exert significant impacts on South China and the southeastern coastal areas, fostering bacterial diseases in rice and increasing uncertainty regarding the emergence of “two‑migration” pests in southern rice‑growing regions, potentially leading to localized, concentrated damage.
     
     

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