National Agricultural Technology Center: It is projected that in 2023, southern rust in the Huanghuaihai summer maize region will face a moderate-to-severe epidemic risk, with an estimated nationwide affected area of 55 million mu.

Release Date:

2023-01-12

　　Recently, the National Agricultural Technology Center convened experts from research, educational, and extension institutions, based on… Corn Based on a comprehensive analysis of factors such as the initial pest and disease population, cropping systems, crop distribution, and climate, it is projected that in 2023, nationwide… Corn Overall, pest and disease outbreaks were relatively severe, affecting a total area of 930 million mu‑times. Of these, insect pests occurred on 630 million mu‑times, while plant diseases affected 300 million mu‑times. The fall armyworm is showing a clear trend of resurgence in the Southwest and South China regions, while the cotton bollworm, the beet armyworm, and southern rust are re-emerging with notable intensity in the Huanghuaihai region, posing a threat to… Corn Production safety poses a significant threat.
　　I. Trend Forecast
　　(1) Pest Infestation
　　The fall armyworm has infested 50 million mu nationwide; with the exception of Heilongjiang, Jilin, Xinjiang, and Qinghai, all other provinces have reported outbreaks. In the Southwest, South China, the Jiangnan region, and the middle and lower reaches of the Yangtze River, multiple generations have occurred and damage is severe, while in the Jianghuai, Huanghuai, Northwest, and North China regions, infestations are relatively mild, with some late‑sown summer crops… Corn Prevalence occurs. Corn The total area affected by stem borers nationwide reached 250 million mu‑times. Specifically, the first generation infested 80 million mu, with moderate outbreaks across most of Northeast China, much of the Huanghuai region, and localized areas in Southwest and South China; the second generation affected 95 million mu, with moderate outbreaks in most of Northeast China, as well as in parts of Southwest China and the Huanghuai region; and the third generation covered 75 million mu, primarily in the Huanghuaihai summer… Corn The pest is expected to occur at a moderate level. The second and third generations of the armyworm are forecast to be moderately prevalent across North China, Northeast China, Northwest China, and Southwest China, with localized areas experiencing concentrated damage; the nationwide affected area is estimated at 65 million mu‑times. The fourth generation of the cotton bollworm is expected to be moderately severe in some parts of the Huanghuaihai region, with a national affected area of 42 million mu‑times. Underground pests are projected to occur at a moderate level across most of Northeast China and in localized areas of North China, covering a national area of 75 million mu‑times. Aphids are expected to be moderately prevalent in Northeast China, Northwest China, most of the Huanghuaihai region, and localized areas of South China, with a national affected area of 76 million mu. The two-spotted armyworm is generally expected to occur at a light level across the Huanghuaihai region, though there is a risk of localized, concentrated damage; the national affected area is estimated at 7 million mu. Beet armyworm, thrips, leaf mites, and the two‑spotted leaf beetle, among others, may cause some damage in certain regions.
　　(II) Diseases and Pests
　　Southern rust in the Huang-Huai-Hai summer region Corn The region faces a relatively high risk of the aforementioned diseases, with an affected area of 55 million mu nationwide. Large spot disease is moderately severe across most of Northeast China, while it is moderate in much of North China, Northwest China, and Southwest China, affecting 80 million mu nationally. Small spot disease is moderate in the middle and lower reaches of the Yangtze River and in Southwest China, with a national incidence of 37 million mu. Brown spot disease is moderately severe in localized areas of North China and moderate across most of the Huang–Huai–Hai Plain, covering 35 million mu nationwide. Ear rot, gray leaf spot, white leaf spot, anthracnose, stem rot, smut, head smut, and dwarfism—among others—pose some level of damage in certain regions.
　　II. Basis for Forecasting
　　(1) In most areas, the pre-winter pest population levels are relatively low; however, there are also regions where baseline populations remain elevated.
　　1. Fall armyworm. From September to November 2022, the number of moths attracted by high-altitude light traps was as follows: Xundian, Yunnan—8,061; Daye, Hubei—1,101; Gaozhou, Guangdong—556; Jiangyong, Hunan—343; Xiaoxian, Anhui—169; Susong, Anhui—69; Yizhou, Guangxi—38; Xingping, Shaanxi—16. Compared with the same period in 2021, Xundian saw a 19% increase, Gaozhou remained unchanged, while Yizhou was only 5% of the level recorded in 2021.
　　2. Armyworms. In 2022, the third generation of armyworms caused only mild to moderate damage across most of northern China, with a nationwide infested area of just 11.2 million mu—about 60% less than the long-term average. From September to November 2022, high-altitude light-trap monitoring indicated generally low migrant populations; however, in Yizhou, Guangxi, and Xingping, Shaanxi, counts reached 1,502 and 661 individuals, respectively—up 25% and 30% compared with the same period in 2021.
　　3. Corn Stem borer. Pre-winter survey. Corn The average number of live stem borers per 100 stalks remained low in Northeast and North China, while it increased somewhat in the Huanghuai region. Specifically, Shandong, Henan, and Jiangsu recorded more than 30 larvae per 100 stalks; Heilongjiang, Liaoning, Tianjin, Shanxi, and Guizhou reported 15–22 larvae; and all other provinces had fewer than 15 larvae. Compared with the 2019–2021 average, levels in Northeast and North China declined by approximately 30%, whereas in most of the Huanghuai region they rose by about 20%.
　　4. Spodoptera exigua. Before winter, overwintering populations were detected in Hebei, Shandong, Shanxi, and Henan provinces, while no such populations were found in Anhui, Jiangsu, Beijing, or Tianjin. The estimated area harboring overwintering larvae was 3.15 million mu, a 47.2% decrease compared with the same period in 2021. In areas where the pest was observed, average larval densities ranged from 0.01 to 0.18 larvae per square meter; in localized plots in Puyang, Henan, and Wenxi, Shanxi, peak densities reached 3 and 2 larvae per square meter, respectively. Total overwintering populations declined by 70% year on year.
　　(2) Corn Crop rotation and cultivation practices are generally favorable for managing pest and disease outbreaks.
　　Our country Corn Cultivation is widespread, with a complex cropping structure; the year-round breeding area is present throughout all four seasons. Corn Cultivation, the migratory flyover zone, and key prevention areas such as the Huang-Huai-Hai region experience spring, summer, and autumn. Corn Cultivation has provided a rich array of host plants for the fall armyworm. In recent years, extensive efforts have been made to promote it across various regions. Soybean Corn Strip intercropping facilitates the sequential damage caused by polyphagous pests such as the beet armyworm, cotton bollworm, and two-spotted leaf beetle. In Northeast China, North China, and the Huang-Huai region… Corn In the main production areas, practices such as no-till farming, straw return to the field, and long-term continuous cropping are widely adopted, all of which facilitate the accumulation of pathogen and pest sources; however, in regions where straw is chopped and incorporated into the soil, this disrupts… Corn Overwintering sites for pests such as the rice stem borer and the peach fruit borer are unfavorable for their overwintering and subsequent emergence. In Northeast and North China, the major cultivated varieties exhibit poor resistance to northern leaf blight, while in the Huang–Huai–Hai region, the dominant cultivars show limited resistance to southern rust, brown spot, and other diseases, thereby facilitating the occurrence and spread of these pathogens.
　　(3) Meteorological conditions are favorable for the occurrence of pests and diseases.
　　According to monitoring and forecasts by the National Climate Center, during December 2022–February 2023, most of Southwest and South China experienced temperatures below normal. Coupled with the influence of the winter La Niña event, this is expected to have a somewhat adverse effect on the overwintering and reproduction of migratory pests such as the fall armyworm and the beet armyworm. In spring 2023, temperatures across most of China are projected to be higher than normal, while precipitation in areas including west-central China and the northeastern part of Southwest China is likely to exceed typical levels for this time of year, creating favorable conditions for the occurrence and spread of diseases and pests. By contrast, reduced rainfall in southern Southwest China and southern South China may hinder the immigration and establishment of migratory pests and the development of epidemic diseases.