During the wheat heading stage, the area affected by Fusarium head blight and aphids totaled 880 million mu‑times, with 76.1% of the affected area occurring in the mid- to late stages.

According to a joint analysis 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 880 million mu. Of this, disease outbreaks will cover 480 million mu and pest infestations 400 million mu. In the mid- to late‑season, these diseases and pests will account for 76.1% of the year’s total affected area. 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 occurrence in the middle and lower reaches of the Yangtze River, the Jianghuai region, and the southern Huanghuaihai wheat belt; sharp eyespot and stem base rot are expected to be moderately to severely prevalent in parts of the Jianghuai and Huanghuaihai areas; and stripe rust is forecast to occur at a moderate level on the Jianghan Plain, in southern Huanghuaihai, and in the central and western parts of the Guanzhong Plain.

I. Occurrence Trend

(1) Diseases

Scab is generally expected to be severe, with a high risk of moderate-to-severe outbreaks in wheat-growing areas south of the Yellow River in Hubei, Anhui, Jiangsu, and Henan; moderate outbreaks are anticipated in northern Henan, southern Shandong, southern Hebei, the Guanzhong region of Shaanxi, and the Sichuan Basin. The projected affected area is 120 million mu, with more than 300 million mu‑times requiring preventive and control measures. The optimal timing for the first chemical application is during the early flowering stage of wheat: mid-to-late April in northern Jianghuai and southern Huanghuai; late April in northern Huanghuai and southern North China; and early-to-mid May in the northwest wheat region.

Overall, stripe rust is expected to occur at a mild level. Moderate outbreaks are anticipated in localized wheat-growing areas, including the Jianghan Plain in Hubei, central and western Anhui, central and western Guanzhong in Shaanxi, southern Henan, eastern Gansu, and the Ili River Valley in Xinjiang. Mild outbreaks are forecast for northwestern Hubei, central Henan, southeastern Shandong, southern Ningxia, and the Sichuan Basin, with an estimated affected area of 25 million mu. The peak incidence is expected from mid-to-late April in the middle and lower reaches of the Yangtze River, from mid-April to mid-May in the Huanghuai region and southern North China, and from late April to mid-May in the northwest wheat-growing areas.

Powdery mildew is generally at a moderate incidence; it is more severe in the central and northern parts of Jiangsu, the northern Weihe Plain in Shaanxi, and the central and northern wheat-growing areas of Henan. In most of Southwest China, the Jianghuai region, much of the Huanghuai area, the central and southern parts of North China, the eastern Northwest, and the Ili River Valley in Xinjiang, the disease occurs at a moderate level. The projected affected area is 90 million mu. The peak period of occurrence is mid-April to early May in the Southwest, the Jianghan Plain, and the Jianghuai region; mid-April to mid-May in the Huanghuai wheat-growing area; and throughout May in the North China and Northwest wheat-growing regions.

Blight disease is generally expected to occur at a severe level, with heavy infestations reported across most of Anhui and Henan provinces and in southern Hebei. Moderate outbreaks are anticipated in the remaining areas of the Jianghuai, Huanghuai, and North China regions. The total affected area is projected to reach 120 million mu. At present, the pathogen has already invaded the stems in the wheat-growing areas of the Jianghan, Jianghuai, and Huanghuai regions, while in North China and Northwest China, the peak incidence is expected from mid-April to early May.

Stem base rot is generally at a moderate incidence level. It is more severe in central and northern Henan, southeastern Shandong, and southern and eastern Hebei, while it occurs at a moderate level in southwestern Shanxi, Guanzhong in Shaanxi, and other wheat-growing areas of the Huanghuai and North China regions, affecting a total area of 50 million mu.

Leaf rust is expected to occur at a mild level across most wheat-growing regions, with moderate incidence in northern Huanghuai; the affected area is projected to reach 40 million mu. Root rot, take-all, leaf blight, and cyst nematode diseases are likely to cause some damage in certain wheat-growing areas of the Huanghuai and North China regions, with an estimated affected area of 30 million mu.

(II) Pest Infestation

Aphids are generally expected to occur at moderate to severe levels, with heavy to very heavy infestations forecast for the Huang-Huai-Hai wheat-growing region and moderate outbreaks across most of the Jianghuai, Southwest, and Northwest wheat areas. The total affected area is estimated at 220 million mu‑times. The peak period of damage will be from late April to mid-May in northern Jianghuai and the Huang-Huai wheat region, and from early May to early June in North China and the Northwest wheat region.

Wheat spider mites are generally occurring at a mild level, primarily in the central and western parts of the Jianghuai, Huanghuai, and North China 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 on 10 million mu in the middle and lower reaches of the Yangtze River, the Jianghuai area, and the southern Huanghuai wheat region; wheat leaf beetles will affect 15 million mu in North China’s wheat belt; and pests such as grain-sucking moths and locusts will cause some damage in certain wheat-growing areas.

II. Forecast Basis

(1) Gibberella head blight, sheath blight, stem base rot, and aphids are present at high population levels and widely distributed.

In areas where Fusarium head blight is endemic, severe outbreaks recur year after year. Continuous rotation of wheat with rice or corn results in substantial straw residues in the fields and high levels of pathogen carriage. In Henan, Jiangsu, Zhejiang, Anhui, and Sichuan, the average incidence of pathogen‑carrying straw per plant ranges from 3% to 10%, close to typical annual levels, thereby meeting the threshold for a widespread epidemic—0.1%. At present, sporadic symptoms have already been observed in wheat-growing regions along the Yangtze River, including Sichuan, Chongqing, Hubei, Anhui, and Zhejiang.

Currently, stripe rust is occurring at a relatively mild level in the southwestern, northwestern, and Jianghuai wheat-growing regions. As of April 11, the disease has been reported in 265 counties across nine provinces—Yunnan, Sichuan, Guizhou, Chongqing, Shaanxi, Hubei, Gansu, Anhui, and Henan—covering a total area of 2.016 million mu. The number of affected counties is close to the lowest level recorded during the same period in 2019, while the affected area is the smallest seen in the past decade for this time of year. In the southwestern wheat region, the epidemic is currently at its peak, with an average incidence of 1%–10% of infected leaves.

Powdery mildew has currently affected 7.788 million mu across the Southwest, Jianghan, Jianghuai, and Huanghuai wheat-growing regions. The average disease‑leaf rate is 1.5%–15.0% in the Southwest, 3.1% in Shanxi, 1.9%–2.2% in Shaanxi and Hubei, and below 0.9% across most of the Jianghuai and Huanghuai areas. Disease severity in Shaanxi, Shanxi, and Henan is higher than at the same time last year, while in most other wheat‑growing areas it is comparable to last year’s level.

Stem base rot has currently affected 15.34 million mu across the North China and Huanghuai wheat-growing regions, with disease incidence generally lower than last year but higher than the long-term average for this time of year. The average incidence rate is 3.1%–3.8% in Shanxi, Henan, and Shandong; 1.5%–1.8% in Shaanxi and Hebei; and sporadic cases have been observed in Anhui.

Currently, net blotch has affected 73.258 million mu of wheat fields in the North China, Huanghuai, and Jianghuai regions, roughly on par with the long-term average for this time of year. The average incidence rate is 7.1%–10.4% in Henan and Shandong, 1.8%–3.5% in Shanxi and Hebei, and 2.7%–4.6% in Jiangsu, Anhui, and Hubei. In most wheat-growing areas, the average incidence rate is slightly lower than last year.

Currently, aphids have infested 48.888 million mu across major wheat-growing regions, a higher area than last year and the long-term average for this time of year. The average number of aphids per 100 plants ranges from 238 to 320 in the southwestern wheat region, 27 to 66 in Shaanxi, Hubei, Anhui, Jiangsu, Henan, Shanxi, and Shandong, and 120 in Zhejiang. Aphids are widespread throughout the North China wheat region, with immigration levels exceeding those of the same period last year.

(2) Wheat cultivation and management practices, along with varietal resistance, favor the occurrence of diseases and pests.

At present, crop conditions in most major wheat-producing areas of the Huanghuai and Jianghuai regions are generally favorable; however, some areas face challenges such as excessively dense stands and uneven developmental stages.

In the middle and lower reaches of the Yangtze River, the Jianghuai region, and the southern Huanghuai area—regions where Fusarium head blight is endemic—the proportion of wheat varieties susceptible to the disease remains high, exceeding 90% across most of Henan, central and northern Anhui, and central and northern Jiangsu, and standing at over 70% in much of Hubei and Sichuan. In these areas, the flowering period of rice‑stubble wheat is uneven, prolonging the window of susceptibility and increasing the likelihood of exposure to prolonged periods of cloudy, rainy weather. Should such adverse conditions occur during the late grain‑filling stage, disease incidence can escalate rapidly.

In the major wheat-producing regions of the Huang-Huai-Hai Plain, wheat varieties generally exhibit poor resistance to stripe rust, sheath blight, and stem base rot, while large areas are planted with susceptible cultivars to powdery mildew and leaf rust.

(3) Weather conditions are conducive to the occurrence of diseases and pests during the heading stage.

According to forecasts from the National Climate Center, in April, temperatures in the eastern wheat‑producing regions are expected to be above normal, while most of North China and the Huanghuai Plain will see 20% to 50% more precipitation—conditions highly favorable for the development and spread of diseases such as wheat powdery mildew and stripe rust. The middle and lower reaches of the Yangtze River and the Jianghuai wheat‑growing area are likely to experience three to four episodes of rainfall, posing a high risk of recurrent Fusarium head blight. In May, most wheat‑growing areas are forecast to have above‑normal temperatures and below‑normal precipitation, creating conditions conducive to the occurrence and damage caused by aphids.

Source: Pest and Disease Forecasting Division