The National Agricultural Technology Center has issued two consecutive early warnings: a severe outbreak of Fusarium head blight and aphids!

　　On April 1, the National Agricultural Technology Extension Service Center issued two consecutive pest and disease alerts, issuing an early warning. Wheat Overall, major pests and diseases were more severe than last year, with Fusarium head blight and aphids experiencing widespread outbreaks, particularly… Wheat Fusarium head blight is experiencing a resurgence.
　　On March 28–29, the National Agricultural Technology Center convened the 2019 National… in Zhumadian City, Henan Province. Wheat A consultation meeting on the trends of pest and disease outbreaks was held. Participants came from across the country. Wheat Technical personnel responsible for forecasting and reporting in the major producing provinces (autonomous regions, municipalities) and experts in plant protection and meteorology from research and educational institutions, based on the current baseline levels of pest and disease occurrence, Wheat Based on a comprehensive analysis of factors such as variety distribution, developmental progress, and future weather trends, it is projected that in 2019, nationwide… Wheat Overall, the incidence of major pests and diseases was higher than last year, with Fusarium head blight and aphids experiencing severe outbreaks. The total affected area nationwide reached 950 million mu, of which 520 million mu were affected by diseases and 430 million mu by insect pests.
　　I. Occurrence Trend
　　(1) Major Diseases
　　Fusarium head blight has become widespread in the middle and lower reaches of the Yangtze River, the Jianghuai region, and the southern Huanghuai wheat-growing areas; it is moderately severe in the northern Huanghuai wheat region, and of moderate severity in other wheat-growing areas. The affected area totals approximately 150 million mu, with about 250 million mu‑times requiring preventive and control measures. The optimal timing for the first chemical application is… Wheat At the early stage of flowering. Specifically, in the middle and lower reaches of the Yangtze River, this occurs in the first and second decades of April; in the Jianghuai region and the southern part of the Huanghuai Plain, it falls in the mid-to-late April; in northern Huanghuai and southern North China, it spans late April to early May; and across most of Northwest China, it extends from late May to early June.
　　Stripe rust has generally been mild overall. Moderate incidence has been observed in wheat-growing areas including the riverine and valley regions of Sichuan, most of Hubei, southern Shaanxi and the western Guanzhong Plain, southern Henan, southern Gansu, and the Ili River Valley in Xinjiang, with some localized fields experiencing moderately severe outbreaks; the affected area totals approximately 25 million mu. The peak epidemic period occurs in the following time frames: early to mid-April in the Southwest and the Han River Basin; mid-April to mid-May in the Huanghuai region and southern North China; mid-May to mid-June in the winter wheat areas of Northwest China; and late June to late July in the spring wheat areas.
　　Powdery mildew occurred at a moderate level overall, with heavier outbreaks in parts of the Huai River region and northern Jiangsu, along the coastal areas, central and northern Henan, and southern Gansu; the affected area totaled 90 million mu. The peak incidence period was mid-April to early May in the Jianghan and Jianghuai wheat-growing regions, late April to mid-May in the Huanghuai wheat-growing region, and May in the North China and Northwest wheat-growing regions.
　　Overall, sheath blight has occurred at a moderate level, with heavier infestations in parts of the Jianghan, Jianghuai, and Huanghuai wheat-growing regions, and lighter outbreaks in the Northwest and Southwest. The affected area totals 120 million mu. At present, stem infection has already begun in the Jianghan and Jianghuai wheat areas, while the peak incidence in the Huanghuai, North China, and Northwest wheat regions is expected from mid-April to early May.
　　The geographic range of stem base rot and root rot has expanded, leaf rust is widespread across most wheat-growing regions, and diseases such as take-all, leaf blight, smut, and cyst nematode disease can cause significant damage in certain areas.
　　(II) Major Pests
　　Aphids have broken out severely in Shandong and Hebei, with moderate to severe outbreaks across most of the Huanghuai region and the central and eastern parts of Northwest China, and moderate infestations in other wheat-growing areas; the total affected area amounts to 220 million mu. The peak period of damage occurs from late April to early May in northern Jianghuai and southern Huanghuai, from mid‑to‑late May in northern Huanghuai and North China, and from late May to mid‑June in the Northwest wheat region.
　　Overall, the rice leafroller is expected to occur at a mild level; however, moderate outbreaks are anticipated in southern Hebei, with localized areas in Nanpi (Hebei), Yicheng (Henan), Xixia, and other regions potentially experiencing high-density infestations. The affected area is projected to reach 15 million mu. The peak emergence of adult moths will occur from mid-April to early May.
　　Wheat spider mites, the first generation of cotton bollworms, the first generation of armyworms, gray planthoppers, wheat leaf bees, wheat stem sawflies, and locusts can cause significant damage in certain regions.
　　II. Forecast Basis
　　(1) The source of Fusarium head blight is widely distributed and abundant, while the initial populations of other pathogens and pests are relatively low.
　　Fusarium head blight: In areas where it is endemic, severe outbreaks have occurred repeatedly in recent years, affecting wheat–rice and wheat–… Corn Continuous cropping, combined with a high in-field straw residue level, has resulted in a total pathogen inoculum that is significantly higher than usual, thereby meeting the conditions for a widespread epidemic. Specifically, in the middle and lower reaches of the Yangtze River and the Jianghuai wheat-growing region, the incidence of pathogen carriage on rice stubble was 2.6%–7.9%, while in the Huanghuai wheat-growing region… Corn The incidence of fungal contamination in straw is 0.5%–4%, and individual rice stubble or… Corn The fungal load in straw residues is also significantly higher than usual. According to recent surveys conducted across various regions, ascospores of Fusarium head blight are approaching their peak release period from south to north, coinciding with local… Wheat The susceptible period for heading and flowering is highly coincident.
　　Stripe rust: To date, the disease has been reported in 235 counties across eight provinces (and municipalities), affecting 3.09 million mu of wheat fields in the Jianghan, Jianghuai, southern Huanghuai, and southwestern wheat-growing regions. The affected area is up 4% year on year, with an onset that was later than usual; overall severity is the lowest it has been in the past five years. At present, the southwestern wheat region has entered the epidemic‑expansion phase, with average disease‑leaf rates ranging from 0.1% to 2.9% in the north and from 16% to 35% in the south—levels close to those of last year. In the Jianghan Plain, outbreaks are localized; in southern Huanghuai, Jianghuai, and most of the northwest wheat‑growing areas, occurrences remain sporadic.
　　Powdery mildew: In most wheat-growing regions, the disease incidence is lower than in recent years. To date, it has affected 2.72 million mu, a 24.9% decrease compared with the same period last year. In the southwestern wheat region, the disease is at its peak, with average leaf‑infection rates ranging from 0.8% to 18%; in most of the Jianghan, Jianghuai, and Huanghuai areas, average rates are between 0.1% and 1.7%. In the northwestern wheat region, average leaf‑infection rates in southern Gansu and Ningxia stand at 6% to 7.9%, while sporadic cases have been observed in Shaanxi; in most of North China, no cases have yet been reported.
　　Sheath blight: Overall disease severity is lower than last year. Currently, it has affected 53.27 million mu across the Jianghan Plain, the Jianghuai region, and the Huanghuai wheat-growing area, a decrease of 18.7% compared with the same period last year. The average incidence rate ranges from 4.2% to 6.4%, with most wheat-growing areas showing a year-on-year reduction of 13% to 40%. Severe outbreaks have been observed in parts of Henan, northern Anhui, and southern Shandong, where the average incidence rate stands at 10% to 15%.
　　Aphids: Population density is lower than in recent years, with current infestations covering 15.05 million mu, a year-on-year decrease of 27.8%. In the Southwest wheat-growing region, aphid activity has entered its peak period, with an average of 89–468 aphids per 100 plants, down 24.2%–47% compared with the same period last year. In the Jianghan, Jianghuai, and Huanghuai wheat regions, the average is 2.5–16.7 aphids per 100 plants, a year-on-year reduction of 52.3%–69%. In localized areas—such as Xuzhou in Jiangsu, Nanchong in Sichuan, and Qianxinan in Guizhou—severe outbreaks have been reported, with aphid counts reaching 1,000–6,000 per 100 plants; in Maguan, Yunnan, the highest count peaked at 20,000 per 100 plants. In the North China and Northwest wheat regions, aphids are occurring sporadically, with average densities generally below 5 per 100 plants.
　　Sucking pests: In the wheat-growing regions of North China, the Huanghuai Plain, and the Jianghuai area, pest densities are lower than last year, and the current period corresponds to the peak activity of larval populations. Spring soil‑sifting surveys indicate an average of 0.2 to 2.9 individuals per quadrat; in most wheat areas, this represents a year‑on‑year decline of 47.6% to 92.3%, while Shaanxi has seen a year‑on‑year increase of 8.3%. The highest recorded densities were 620, 55, and 24 individuals per quadrat in Yicheng and Xixia in Henan, and Nanpi in Hebei, respectively.
　　(II) Variety Layout and Wheat The developmental stage is conducive to the occurrence of pests and diseases.
　　Areas where Fusarium head blight is frequently prevalent Wheat There has been no significant change in the varietal composition, with susceptible varieties accounting for as much as 90% of plantings across the middle and lower reaches of the Yangtze River, the Jianghuai region, and the Huanghuai wheat-growing area. Wheat There is considerable variation in the progression of grain development, and the flowering period is highly uneven, which prolongs the susceptible window and increases the likelihood of exposure to prolonged periods of overcast, rainy weather. Moreover, in frequently affected regions such as the middle and lower reaches of the Yangtze River and the Jianghuai area, Fusarium graminearum has developed heightened resistance to carbendazim, reducing the efficacy of chemical control and intensifying the threat of widespread disease outbreaks. This poses a growing risk to the major wheat-producing areas of the Huang-Huai-Hai Plain. Wheat Varieties with poor resistance to stripe rust, along with those susceptible to powdery mildew, leaf rust, and other diseases, are widely cultivated in contiguous monoculture, creating favorable conditions for disease outbreaks. Huanghuaihai Wheat Region Wheat The heading and flowering stage coincides closely with the emergence of adult grain‑sucking insects, which facilitates their oviposition and subsequent damage.
　　(3) Weather conditions are conducive to the occurrence of mid- and late-season pests and diseases.
　　According to forecasts from the National Climate Center, in April, most wheat-growing regions are expected to experience temperatures 0.5–2°C above normal, with eastern North China, eastern Huanghuai, and northeastern Jianghuai seeing anomalies of 2–3°C. Precipitation in the middle and lower reaches of the Yangtze River, the Jianghuai region, and southern Huanghuai is projected to be 10–20% above average, locally even 20–50% above; in May, most wheat areas will see temperatures 0.5–1°C above normal, with Huanghuai and Jianghuai experiencing anomalies of 1–2°C. Rainfall in the middle and lower Yangtze River basin and the Jianghuai region is expected to be 10–20% above average, while northern North China and northern Huanghuai may see 10–20% below average, locally as much as 20–50% below. In the central and eastern parts of Northwest China, precipitation is forecast to be near normal or below average. Favorable weather conditions are likely to promote the spread of Fusarium head blight and stripe rust in the middle and lower Yangtze River, Jianghuai, and southern Huanghuai wheat regions, as well as the proliferation and damage caused by aphids during the grain-filling stage in northern North China, northern Huanghuai, and the central and eastern Northwest. However, these conditions are generally unfavorable for the spread of stripe rust in the central and eastern Northwest wheat region.
　　This year, the pathogen inoculum in the fields is abundant, the proportion of susceptible varieties planted is high, and rainfall during the heading and flowering stages has been above average; it is anticipated that… Wheat 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-growing areas; it is expected to be moderately severe in northern Huang-Huai, with moderate incidence elsewhere. The affected area is approximately 150 million mu, while the total area requiring preventive and control measures amounts to about 250 million mu‑times. The optimal timing for the first chemical application is… Wheat At the onset of flowering, the timing varies: in the middle and lower reaches of the Yangtze River, it occurs in early to mid-April; in the Jianghuai region and southern Huang-Huai, from mid- to late April; in northern Huang-Huai and southern North China, from late April to early May; and across most of Northwest China, from late May to early June.
　　I. The pathogen inoculum in the fields of the epidemic area is abundant, meeting the conditions for a widespread outbreak.
　　In recent years, Fusarium head blight has repeatedly broken out with severe outbreaks in its endemic regions, including the middle and lower reaches of the Yangtze River, the Jianghuai area, and the southern Huang-Huai Plain. Wheat–rice, wheat–… Corn Continuous cropping, combined with a high in-field straw residue level, has resulted in a total pathogen inoculum that is significantly higher than usual, meeting the conditions for a widespread epidemic. Specifically, on the Jianghan Plain in Hubei, the incidence of pathogen carriage on rice stubble ranged from 4.5% to 5.8%, with Dangyang reaching as high as 47.4%, while in the northern Hubei hilly areas it was 0.6% to 3.6%. In Anhui, the pathogen carriage rate on rice stubble varied from 0.5% to 2.6%, rising to 3.2%–7.9% along the Yangtze River, and in the wheat-growing regions of northern Anhui… Corn The incidence of pathogen carriage in straw is typically 0.5%–4%; in Jiangsu, the pathogen carriage rate in rice stubble generally ranges from 1% to 2%, with some wheat-growing areas exceeding 5%, and the number of pathogens carried by individual rice stubble is significantly higher than usual; Pingyu, Henan. Corn The incidence of pathogenic fungi in straw was 2.7%, an increase of 1.1 percentage points year on year.
　　II. The susceptibility of a variety is closely aligned with the timing of its susceptible growth stages and the pathogen’s infection period.
　　Major wheat-growing regions Wheat There has been no significant change in the variety mix, with susceptible varieties accounting for 90% of the planted area. At present, Wheat In the Yangtze River and Jianghuai wheat-growing regions, crops are at the booting to heading stages, while in the Huang-Huai region they are still in the booting stage. Within the same area, phenological development varies considerably, leading to highly uneven flowering periods. This prolongs the susceptible window for disease and increases the likelihood of prolonged rainy weather, thereby heightening the threat of Fusarium head blight epidemics. According to surveys conducted across different localities, pathogen development is progressing at a pace similar to that of an average year, with peak ascospore release occurring around… Wheat The timing of anthesis closely coincides with the period of greatest susceptibility to disease. Furthermore, in areas where the pathogen is prevalent, Fusarium graminearum has developed increased resistance to carbendazim, resulting in a marked decline in control efficacy.
　　III. Weather conditions are conducive to the spread of Fusarium head blight.
　　According to forecasts from the National Climate Center, in April, the middle and lower reaches of the Yangtze River, the Jianghuai region, and the southern Huanghuai wheat-growing areas are expected to see 10–20% above-normal precipitation, with some localized areas receiving 20–50% more; meanwhile, temperatures across most of these regions will be 0.5–2°C higher than average, creating highly favorable conditions for the spread and damage caused by Fusarium head blight. In May, the middle and lower Yangtze River basin and the Jianghuai wheat-growing areas are projected to experience 10–20% above-normal rainfall, further exacerbating the severity of Fusarium head blight in these regions. In North China and the northern Huanghuai area, precipitation is expected to be 10–20% below normal; however, widespread irrigation during the grain-filling stage will maintain high field humidity, and frequent occurrences of smog and condensation will increase the likelihood of pathogen infection, thereby promoting the epidemic spread of the disease.
　　 Wheat Fusarium head blight is a quintessential climate‑driven epidemic disease, characterized by rapid spread, wide geographic distribution, and severe damage. In response to this year’s… Wheat With the susceptible reproductive period, pathogen infection period, and favorable weather conditions all coinciding, the severe situation of a pronounced resurgence of Fusarium head blight calls for utmost attention; local authorities must closely monitor local weather changes and… Wheat During the growing season, timely issuance of disease‑alert information guides farmers and specialized cooperative organizations to apply fungicides at the appropriate time for preventive control, thereby minimizing the incidence and damage caused by Fusarium head blight and ensuring… Wheat Production safety.

Source: National Agricultural Technology Extension Service Center Author: National Agricultural Technology Extension Service Center Editor: bianji2