2023 National Forecast of the Occurrence Trends of Major Wheat Diseases and Pests

According to a joint analysis conducted by experts from the national plant protection system and research and educational institutions, organized by the National Agricultural Technology Extension Center, major wheat diseases and pests are expected to occur at a relatively severe level nationwide in 2023, affecting a total area of 860 million mu‑times. Of this, disease outbreaks are projected to cover 460 million mu‑times, while pest infestations will affect 400 million mu‑times. Aphids are likely to occur at moderate to severe levels across most wheat-growing regions in the Huang–Huai–Hai Plain; Fusarium head blight poses a high risk of widespread epidemics in the middle and lower reaches of the Yangtze River, the Jianghuai region, and the southern Huang–Huai wheat belt; sharp eyespot is expected to be moderately to severely prevalent in the North China wheat region; and stripe rust may occur locally at moderate to severe levels in the Han River basin and the northwest wheat-growing areas.

I. Occurrence Trend

(1) Diseases

Scab is generally expected to be severe, with a high risk of moderate-to-severe outbreaks across most of Hubei, northern Zhejiang, much of Anhui, the central and southern parts of Jiangsu, and southern Henan. Moderate to severe outbreaks are anticipated in northern Jiangsu, central and northern Henan, southern Shandong, the Guanzhong region of Shaanxi, and the northern and eastern parts of Sichuan. The projected affected area is 90 million mu, with approximately 300 million mu requiring preventive and control measures.

Stripe rust is expected to be moderately widespread overall, with a high risk of severe outbreaks in most of Hubei, southern Henan, and southern Gansu. Moderate incidence is anticipated in central and northern Henan, central and western Anhui, southeastern Shandong, the Sichuan Basin, most of Shaanxi, central and eastern Gansu, southern Ningxia, and the Ili River Valley in Xinjiang. The projected affected area is 40 million mu.

Powdery mildew is generally at a moderate incidence; it is more severe in central and northern Jiangsu, western Shandong, and eastern and northern Henan, while most other wheat-growing areas in the Huanghuai, North China, and Northwest regions are experiencing moderate levels. The projected affected area is 90 million mu.

Blight disease is generally expected to occur at a severe level, with heavy infestations reported across most of Henan, Shandong, and Anhui provinces, as well as in central and northern Jiangsu and southern Hebei. Moderate outbreaks are anticipated in other wheat-growing areas of the Jianghuai, Huanghuai, and North China regions. The total affected area is projected to reach 120 million mu.

The projected area affected by other diseases is 120 million mu, with incidence ranging from mild to moderate. Specifically, stem base rot is expected to worsen across most wheat-growing regions in the Huanghuai and North China plains, affecting approximately 50 million mu; leaf rust will occur on 40 million mu in the North China, Huanghuai, Jianghuai, Southwest, and Northwest wheat areas; and root rot, take‑all, leaf blight, and other diseases are likely to cause some damage in certain wheat-growing areas of the Huanghuai and North China, with an estimated affected area of 30 million mu.

(II) Pest Infestation

Aphids are expected to occur at a generally severe level, with heavy to very heavy infestations in the Huanghuaihai wheat region and moderate infestations across most of the Jianghuai, Southwest, and Northwest wheat-growing areas; the projected affected area is 220 million mu.

Wheat spider mites are expected to occur at moderate levels overall, primarily in the central and western parts of the Jianghuai, Huanghuai, and North China wheat-growing regions, as well as in the central and eastern parts of the Northwest. The projected affected area is 90 million mu.

Other pest outbreaks are expected to affect 85 million mu, with an overall tendency toward mild infestations. Specifically, underground pests will occur across 40 million mu in the wheat-growing regions of Northwest and North China; the first-generation armyworm will be prevalent in the middle and lower reaches of the Yangtze River, the Jianghuai area, and the Huanghuai region.

In the southern wheat-growing region, the pest has infested 10 million mu; in the North China wheat-growing region, the wheat leaf beetle has affected 15 million mu; and pests such as the grain-sucking fly and locusts are expected to infest 20 million mu in certain wheat-growing areas.

II. Basis for Forecasting

(1) The pre-winter population levels of scab, powdery mildew, aphids, and wheat spider mites are relatively high, while those of stripe rust, sheath blight, and grain-sucking insects are relatively low.

The pathogen population of Fusarium head blight has been steadily accumulating and remains abundant year after year. In recent years, severe outbreaks have recurred in wheat-growing regions along the middle and lower reaches of the Yangtze River, as well as in the Jianghuai and Huanghuai areas, with a pronounced eastward shift and northward expansion of the affected area. In most wheat-growing regions, wheat is rotated with maize and rice, resulting in substantial residues of straw in the fields—providing an important substrate for the reproduction and buildup of the pathogen. Consequently, the level of pathogen inoculum in these major wheat-producing areas meets the threshold conditions necessary for widespread epidemics.

In the main autumn‑sown wheat stripe rust–infested area of Northwest China, the affected acreage was relatively small, with overall disease severity higher than in 2021 but lower than the long-term average. As of December 5, 2022, the disease had been detected in 37 counties across 12 cities (prefectures) in the four provinces/regions of Gansu, Ningxia, Qinghai, and Shaanxi, covering 859,000 mu—making it the third‑smallest outbreak since 2010. The affected area was 23.1% larger than during the same period in 2021, when the disease was mild, but 66.4% smaller than the 2016–2020 average; the number of affected counties increased by 11 compared with 2021, yet remained 14 fewer than the 2016–2020 mean. Among these, Dingxi in Gansu and Guyuan in Ningxia experienced particularly severe outbreaks, with average incidence rates exceeding 30% in each. In the Southwest winter‑breeding region, sporadic cases were reported in five counties across three cities—Sichuan, Guizhou, and Yunnan—with the first signs of infection appearing 9 to 18 days earlier than during the same period in 2021.

The initial incidence of powdery mildew on autumn seedlings is relatively high. In certain wheat-growing regions—including the Northwest, Huanghuai, and Southwest—disease has been observed on autumn seedlings, affecting 2.893 million mu, an increase of 55.5% compared with the same period in 2021 but a decrease of 30.8% relative to the average for 2016–2020. The average disease‑leaf rate stands at 4.9%, far exceeding the 0.05% recorded in the same period of 2021 and the 0.54% average for 2016–2020. In eastern and southern Gansu, early‑sown and vigorously growing fields have experienced more severe outbreaks, with an average disease‑leaf rate of 6.6%, peaking at 60%. In Shanxi, the average disease‑leaf rate is 2.6%, up 160% from 2021 and 280% above the long-term average. In Shaanxi, the average disease‑leaf rate is 0.18%, lower than the 0.2% in 2021; however, in Tongguan and Yintai, the average rates reach 3% to 4.8%. In northern Henan, sporadic cases have been reported, with disease levels close to the long-term average, while in Sichuan, isolated occurrences have been noted, with conditions similar to those of the same period in 2021 but milder than usual.

The incidence of sheath blight on autumn seedlings was relatively limited, with disease severity lower than in 2021 and the long-term average. In wheat-growing regions such as the Huanghuai and North China, the affected area totaled 6.554 million mu, up 6.9% year-on-year compared with the same period in 2021, but down 5.7% from the average of 2018–2020. The national average disease‑plant rate was 1.4%, below the 2.8% recorded at the same time in 2021 and the 1.9% average for 2018–2020. Specifically, Shandong and Henan reported average disease‑plant rates of 1.8% and 1.4%, respectively, while Hebei and Shanxi recorded 1.0% and 0.8%, all lower than both 2021 levels and the long-term averages; in Yongnian, Hebei, the highest rate reached 6.5%.

Before winter, aphid populations remained relatively high across most wheat-growing regions. Nationwide, the area affected by autumn seedling infestations totaled 9.519 million mu, up 36.2% from the same period in 2021 but down 37.8% compared with the average of 2016–2020. By region, the average number of aphids per 100 plants ranged from 1.2 to 8.0 in Jiangsu, Gansu, Hubei, Shanxi, Shaanxi, and Hebei—levels all higher than in the same period of 2021—while Anhui recorded 15.6 and Shandong 2.1, both lower than the respective figures of 22.7 and 8.0 in 2021.

The area affected by wheat spider mites before winter was relatively large, with pest populations remaining high. In the wheat-growing regions of the Huanghuai, Jianghuai, North China, and Northwest China, the infested area totaled 12.185 million mu, up 49.5% from the same period in 2021 and 2.1% above the average for 2018–2020. Nationwide, the average number of mites per linear foot of row was 12.9, exceeding both the 6.3 recorded in the same period of 2021 and the 7.3 average for 2018–2020. Specifically, in Henan, Shaanxi, Shanxi, Anhui, and Hubei, the average mite count per linear foot ranged from 10.9 to 32, higher than in the corresponding period of 2021.

The rice leaf folder exhibits relatively low population densities in the Yellow–Huai–Hai Plain and the Northwest, which are its common outbreak areas. Nationwide, the average density is 0.54 individuals per quadrat, lower than 0.9 in the same period of 2021 and 1.2 in the average for 2018–2020. By region, the averages are 0.2 and 0.5 individuals per quadrat in Hebei and Shaanxi, respectively—both below the levels recorded during the same period in 2021. In Xixia, Henan, and Fufeng, Shaanxi, peak densities reached 8 and 9 individuals per quadrat, respectively; however, even in these high‑density fields, both the infestation levels and the total numbers of pests were markedly lower than in the corresponding period of 2021.

(2) Variety resistance and cropping systems favor the occurrence of pests and diseases.

In most wheat-growing regions across the country, winter wheat varieties exhibit low levels of resistance to diseases such as Fusarium head blight, stripe rust, powdery mildew, sheath blight, and stem base rot. According to monitoring data, in Shaanxi, Henan, Anhui, and Shandong, the majority of wheat varieties remain susceptible to Fusarium head blight. In disease‑prone areas of Gansu and Shaanxi, the proportion of resistant varieties has increased somewhat; however, the virulent and broadly pathogenic race 34 of stripe rust continues to be the dominant race. In major wheat‑producing regions such as Hubei, Henan, and Shandong, the resistance of cultivated varieties to stripe rust is generally moderate. Moreover, varieties grown in these key production areas also show limited resistance to powdery mildew and sheath blight. During the autumn of 2022, temperatures were higher than average and rainfall was above normal across much of the winter wheat belt, leading to vigorous vegetative growth in many areas—conditions that are unfavorable for disease and pest management.

(3) Meteorological conditions are conducive to the outbreak and spread of aphids and Fusarium head blight.

According to forecasts from the National Climate Center, during the 2022 winter season (December 2022–February 2023), most of China is expected to experience above‑normal temperatures and below‑normal precipitation, with no significant adverse conditions for overwintering pests and diseases. In the 2023 spring season (March–May), temperatures across much of the country are likely to be higher than average, while parts of southwestern and northeastern China, as well as much of northwest China, are expected to see above‑average rainfall, creating favorable conditions for the occurrence and spread of stripe rust and powdery mildew. In contrast, much of North China is forecast to receive below‑average precipitation, which could promote a rapid increase in wheat aphid and wheat spider populations. Meanwhile, the middle and lower reaches of the Yangtze River, the Jianghuai region, and most of the Huanghuai area are expected to receive normal rainfall, generally benefiting pest and disease development. However, during the heading and flowering stages of wheat in the middle and lower Yangtze, the Jianghuai, and southern Huanghuai regions, prolonged periods of cloudy and rainy weather may occur, thereby facilitating the outbreak and spread of Fusarium head blight.

Source: Pest and Disease Monitoring and Forecasting Division, National Agricultural Technology Center