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 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. Specifically, 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 Huanghuaihai 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 part of the Huanghuaihai Plain; sharp eyespot is expected to be moderately to severely prevalent in the North China wheat belt; and stripe rust may occur locally at moderate to severe levels in the Han River basin and certain areas of the Northwest wheat region.

I. Trend of Occurrence

(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 districts 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 overall incidence projected as mild. Specifically, underground pests will infest 40 million mu in the wheat-growing regions of Northwest and North China; the first-generation armyworm will occur in the middle and lower reaches of the Yangtze River, the Jianghuai area, and the Huanghuai region.

In the southern wheat-growing region, the infestation covers 10 million mu; in the North China wheat-growing region, the wheat leaf beetle is expected to affect 15 million mu; and pests such as the grain-sucking fly and locusts are forecast to infest 20 million mu in certain wheat areas.

II. Basis for Forecasting

(1) Prior to winter, the initial population levels of scab, powdery mildew, aphids, and wheat spider mites were relatively high, while those of stripe rust, sheath blight, and grain-sucking insects were comparatively low.

The inoculum 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 proliferation and buildup of the pathogen. Consequently, the level of pathogen inoculum in these key wheat-producing areas meets the threshold conditions necessary for large-scale epidemics.

In the main autumn‑seedling outbreak region of Northwest China, the affected area was relatively small, with overall disease severity greater than in 2021 but milder than the long-term average. As of December 5, 2022, the four provinces/regions—Gansu, Ningxia, Qinghai, and Shaanxi—reported cases in 37 counties across 12 cities/prefectures, covering 859,000 mu; this marked the third‑smallest outbreak since 2010. The affected area increased by 23.1% compared with the same period in 2021, when the outbreak was mild, but was 66.4% lower than the 2016–2020 average. The number of affected counties rose by 11 year over year, yet remained 14 fewer than the 2016–2020 average. 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‑propagation zone, sporadic diseased fields were observed 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 parts of the Northwest, Huanghuai, and Southwest wheat-growing regions, the disease has appeared on 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, though in Tongguan and Yintai, the rates reach 3%–4.8%. In northern Henan, sporadic cases have been observed, with disease levels close to the long-term average; in Sichuan, isolated occurrences have been reported, with conditions similar to those of the same period in 2021 but milder than usual.

The incidence of sheath blight on autumn-sown wheat was relatively limited, with disease severity lower than in 2021 and the long-term average. In major wheat-growing regions such as the Huanghuai and North China areas, the affected area totaled 6.554 million mu, up 6.9% from the same period in 2021 but down 5.7% compared with the average for 2018–2020. The national average disease incidence 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 incidences 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 incidence reached 6.5%.

Prior to winter, aphid populations remained elevated 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 aphids per 100 plants 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 on a single 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, also 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 of 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 number of individuals and overall infestation levels 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 like Gansu and Shaanxi, the proportion of resistant varieties has increased, yet the virulent strain Triticum aestivum pathotype 34 continues to dominate; 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 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 exceeded normal levels 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 precipitation in parts of southwestern and northeastern China and in much of northwest China is expected to exceed normal levels, creating favorable conditions for the occurrence and spread of stripe rust and powdery mildew. In contrast, reduced rainfall in much of North China may promote a rapid increase in wheat aphid and wheat spider populations. Precipitation in the middle and lower reaches of the Yangtze River, the Jianghuai region, and most of the Huanghuai area is expected to be near normal, generally conducive to pest and disease development. 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 could facilitate the outbreak and spread of Fusarium head blight.

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