Corn grain filling—act quickly to control these pests and diseases.

　Currently, in the Northeast region, spring... Corn Most are in the grain-filling stage, Huang-Huai-Hai summer. Corn During the grain-filling stage, spring Corn Most are in the milk-ripe stage, with spring crops in the southwest and northwest regions. Corn Most are in the wax-ripe to harvest stage. Various types… Corn Overall pest and disease incidence was moderate, affecting 280 million mu of farmland, with the fall armyworm being… Corn The main pests and diseases include stem borers, cotton bollworms, the third-generation armyworm, red spiders, two-spotted leaf beetles, aphids, and grass cutworms, as well as diseases such as northern corn leaf blight, southern rust, and small spot disease.
　　Situation of Fall Armyworm Outbreak
　　As of August 17, the fall armyworm has been detected in 1,366 counties (cities and districts) across 24 provinces in China, with a nationwide infested area of 14.31 million mu. Control measures have been implemented on 20.65 million mu, yielding an average control coverage rate of 144% and an average efficacy of approximately 90%. In August, 86 additional counties reported outbreaks, adding 1.7 million mu of infested area and 3.02 million mu under control. Overall, the spread and development of the fall armyworm exhibit the following characteristics: First, its northward expansion continues. North of the Yellow River, Henan and Shanxi now each have 4 and 6 affected counties or cities, respectively; in Hebei, adult moths were observed in Luancheng and Wei County on August 16, and larvae were found there as well. To date, six counties or cities are affected, with the northernmost records reaching Xinji and Luancheng in Shijiazhuang. In northern provinces such as Ningxia, Gansu, Shaanxi, and Shandong, new outbreak sites continue to emerge; these seven provinces accounted for 79% of all newly affected counties in August. Second, newly affected areas are distributed in distinct bands. This month, the majority of new counties are concentrated in eastern Ningxia, central Shaanxi, southern Shanxi, northern Henan, southern Shandong and the Jiaodong Peninsula, as well as central and northern Jiangsu—forming a band-like pattern on the map. Third, adult moths have been repeatedly trapped in many parts of Ningxia. In the rapidly expanding western region, the pest has appeared in 13 counties (cities and districts), with a total of 1,025 moths captured: 1,022 by sex pheromone traps and 23 by high-altitude monitoring lamps. Currently, sporadic egg masses are present in fields, but no larval damage has been observed.
　　Other pest occurrence情况
　　 Corn The cumulative area affected by stem borers nationwide reached 110 million mu, with overall infestation ranging from light to moderate and localized outbreaks of heavier severity. Among these, Heilongjiang… Corn The stem borer has generally been a serious pest, affecting 15.99 million mu of land, with the central and western regions being the primary areas of infestation. Inner Mongolia. Corn Stem borers occurred at a moderate level, with localized outbreaks of greater severity, affecting 17.7 million mu‑times; among these, the second generation… Corn The stem borer has infested 7.86 million mu, with an average incidence of 6%–13% of plants affected and a maximum of 27%; pest density ranges from 6 to 23.5 larvae per hundred plants, with a peak of 60 larvae per hundred plants. Shanxi—first generation. Corn The stem borer is occurring at a relatively mild level in the central and northern regions, affecting 1.67 million mu of land. The average incidence rate per plant is 6%–8%, with a maximum of 12%; there are 5–8 larvae per 100 plants, up to a maximum of 13. This refers to the second generation. Corn The stem borer is occurring at a relatively mild level in the southern regions, affecting 840,000 mu of land. The average incidence of damaged plants ranges from 1% to 4%, with an average of 0.5 to 2 larvae per 100 plants. In Shaanxi, the second generation… Corn The pest occurred at a mild level, with moderate incidence in Hanzhong. Across the province, the affected area totaled 2.93 million mu, with an average damage rate of 3.8% and 2.9 larvae per 100 plants. The highest damage rate reached 25%, and the peak larval density was 30 larvae per 100 plants. In Anhui, the pest infested 5.01 million mu‑times, with typical damage rates ranging from 0.3% to 5.3%; in Funan, Nanqiao, and Feidong, these rates were 7.6% to 11.7%. Larval densities generally ranged from 0.2 to 4 larvae per 100 plants, yielding a provincial weighted average of 0.75 larvae per 100 plants. In Ningxia, the pest affected 180,000 mu, with an average damage rate of 7% and an average larval density of 7 larvae per 100 plants.
　　The cotton bollworm has generally been a minor pest, with more severe outbreaks in localized areas such as Shanxi. The affected area totals 50 million mu, of which Shandong accounts for 1.79 million mu. In Tai’an, Jining, and Jinan, the incidence rates are 9.6%, 6.5%, and 5%, respectively. In Jining, the average number of larvae per 100 plants is 2.7, with a maximum of 16. The outbreak is concentrated in central and southern Shanxi. Corn Tian Fasheng reported that in southern Shanxi, the average number of pests per 100 plants was 5–8, with a maximum of 15; in central Shanxi, localized damage was severe, concentrated in… Corn The larvae feed at the tip of the female ear, partially severing the silk tassels and thereby impairing pollination. The pest density ranges from 30 to 60 larvae per 100 plants, with a damage incidence of 40% to 60%; the larvae are in instars 2 through 6. In Shaanxi, the pest occurs only lightly in Weinan and Xianyang, affecting 410,000 mu, with an average damage incidence of 3.9% and a maximum of 11%. In Ningxia, it infests 80,000 mu, with an average damage incidence of 2.5% and an average of 5 larvae per 100 plants. In Anhui, the pest has been recorded on 1.23 million mu‑times, with damage incidences ranging from 0.1% to 1.5% across different localities and larval densities of 0.1 to 1.3 per 100 plants.
　　In the third generation, the armyworm has infested 13.2 million mu nationwide, with 2.8 million mu reaching the threshold for control and 1.2 million mu experiencing severe outbreaks. Overall damage is lighter than in the previous two years. However, localized outbreaks have been relatively severe in certain counties (districts) of Liaoning, Inner Mongolia, Heilongjiang, Hebei, Beijing, and Tianjin, particularly in areas with lax management and abundant weeds. Corn High-density, localized outbreaks have been observed in sorghum, millet, and rice fields.
　　Red spider mites have occurred at a relatively severe level in Inner Mongolia, Shanxi, Ningxia, and other regions, affecting 10 million mu of land. In Inner Mongolia alone, the infestation covers 2.8 million mu, with an average of 100–800 mites per plant; in Ordos City, individual plants harbor 2–6 mite‑infested leaves, with some severely affected plants showing as many as 10–11 such leaves. In Chifeng City, typical counts range from 3,000 to 20,000 mites per 100 plants, with mite‑infested plant rates of 20%–40%; in heavily re‑infested areas, the rate reaches 100%, and mite populations can soar to 100,000–150,000 per 100 plants, with some severely affected plots exhibiting dry, withered foliage. In QingShuiHe County, Hohhot, localized outbreaks have been reported, with individual plants harboring up to 10,000 mites, concentrated on the lower 3–5 leaves. In northern Shanxi, particularly in the Xinding Basin, certain fields are experiencing severe infestations: in Yuanping City, mites have advanced to the third leaf stage, with some plants showing heavy infestation on the flag leaf; mite densities reach 150,000–200,000 per 100 plants, and in isolated cases even 300,000. In Shuozhou, mite counts range from 50,000 to 100,000 per 100 plants, with peak densities approaching 100,000. In Pingcheng District, Datong, re‑infested fields exhibit 30,000–50,000 mites per 100 plants. In Ningxia, the affected area totals 2.1 million mu, with an average mite‑infested plant rate of 75%, a mite‑infested leaf rate of 45%, and mite populations averaging 400 per plant, though some individual plants host as many as 3,000.
　　The two-spotted leaf beetle has infested 12 million mu, with moderate outbreaks in localized areas of Inner Mongolia, Shanxi, and other regions. In Inner Mongolia, the affected area totals 5.32 million mu, with moderate incidence primarily concentrated in Chifeng City, Hulunbuir City, Hinggan League, Tongliao City, and Bayannur City; average densities range from 5 to 6 beetles per plant, with a maximum of 10 per plant. In northern Shanxi, including Datong and Shuozhou, moderate outbreaks have been reported over 1 million mu, with an average of about 300 beetles per hundred plants and a peak of 1,000. In Shaanxi, the infestation is relatively mild, covering 1.79 million mu, with an average damage rate of 13.5% and a maximum of 61.9%; average densities are 20 beetles per hundred plants, with a maximum of 613. In Ningxia, the affected area stands at 1.5 million mu, with a damage rate of 6.5% and an average of approximately 12 beetles per hundred plants, peaking at 138.
　　Aphid infestations have affected 20 million mu, with moderate outbreaks in localized areas of Ningxia, Inner Mongolia, and other regions. In Inner Mongolia, the infested area totals 1.19 million mu, with pest densities ranging from 450 to 20,000 aphids per 100 plants and damage rates between 6% and 48%. In Ningxia, the affected area stands at 2.88 million mu, with an average of 300 aphids per 100 plants and a peak of 6,800 per 100 plants. In Shaanxi, the situation is mild, with 1.51 million mu affected; the average density is 148 aphids per 100 plants, and the highest recorded density reaches 20,000 per 100 plants.
　　The second generation of grass cutworm larvae has infested 500,000 mu, primarily in Hinggan League, Chifeng City, Bayannur City, Hulunbuir City, and Tongliao City in Inner Mongolia. In Hinggan League, the average larval density is 15 larvae per square meter, with a maximum of 110 larvae per square meter.
　　Disease incidence situation
　　Recently Corn Overall disease incidence is moderate, with major pathogens including northern leaf blight, southern leaf blight, brown spot, southern rust, and sheath blight.
　　Large spot disease is primarily severe in parts of Northeast China, northern North China, and the northwest, affecting 22 million mu. In Heilongjiang, the overall incidence is moderate, concentrated in the central and western regions, slightly higher than in the previous two years but still among the milder years since 2011, with an affected area of 8.22 million mu. In Inner Mongolia, the disease has spread over 4.53 million mu, with moderate overall incidence and localized severe outbreaks, mainly in Hinggan League, Hulunbuir City, and Chifeng City. The average incidence of diseased plants is 35%, with a maximum of 100%; the average incidence of diseased leaves is 23.4%, peaking at 65%. In Hebei, the affected area totals 630,000 mu, with an average incidence of about 4% and a maximum of 14%, and an average leaf‑disease rate of around 3%, reaching as high as 16%. In Chengde County in the north, typical fields show a diseased‑plant rate of 8–10%, while severely affected plots reach 29%. In Shanxi, the Xinding Basin experiences moderate incidence across 1.2 million mu; in Xinzhou, the average incidence of diseased plants is approximately 30%, with a peak of 60%, and the average leaf‑disease rate is about 10%, with a maximum of 20%. In Shaanxi, the disease is mild, covering 1.58 million mu, with a provincial average incidence of 6.2% and a maximum of 77.1%. In Ningxia, the affected area spans 1.33 million mu, with an average incidence of 35% for plants and 10% for leaves. In Sichuan, the situation is more severe than last year, with an average incidence of 10.9%; in Han’yuan County in the western mountainous region, the average incidence reaches 25%.
　　Small spot disease occurred at a mild level, affecting 4.0 million mu of land. In Shaanxi, the affected area totaled 340,000 mu, with an average incidence rate of 7.8% per plant and a maximum incidence rate of 76%. In Ningxia, the affected area was 550,000 mu, with an average incidence rate of 28% per plant and an average disease‑leaf rate of 3.8%.
　　Recently, southern rust has been advancing rapidly in the Huanghuai region and other areas, with widespread incidence reported in Weihai, Shandong, where the percentage of infected leaves has reached 30%.
　　Next-step trend
　　In China, Yunnan, Guangxi, Guangdong, and Hainan must continue to closely monitor the fall armyworm and track its overseas sources. The prevailing southwest winds from Myanmar will provide favorable meteorological conditions for the pest’s entry into Yunnan, while infestations originating in Vietnam and Laos pose an immediate threat to the Guangdong–Guangxi region and Hainan. Outside these four southern provinces, influenced by passing typhoons and the steady southward movement of northerly winds, the likelihood of further northward migration of the fall armyworm across eastern China in mid-to-late August has diminished; instead, its spread is expected to be largely confined within provinces or to neighboring regions.
　　According to forecasts from the National Climate Center, over the next 10 days, cumulative rainfall in Xinjiang’s Ili River Valley, the central and northern parts of Northeast China, eastern Northwest China, central and western North China, South China, Yunnan, Sichuan, and other regions is expected to range from 50 to 80 millimeters, with some areas receiving 100 to 150 millimeters and localized spots exceeding 200 millimeters. In most of these areas, precipitation is likely to be above normal for this time of year, which could favor the development of diseases such as leaf spot, southern rust, and stalk rot, Corn Favorable conditions for the occurrence of pests and diseases such as stem borers are present; in southern Shaanxi, western Huanghuai, Jianghan, western Jianghuai, Jiangnan, and northern South China, predominantly high-temperature weather is unfavorable for the emergence of most pest species, including the fall armyworm, aphids, and cotton bollworm.

 

Source: Pest and Disease Monitoring Division, National Agricultural Technology Center Author: Pest and Disease Monitoring Division, National Agricultural Technology Center Editor: bianji2