The impact of pests and diseases was relatively severe in mid-May 2017 in the main wheat regions of China, at a time when the crop was mainly in the mid and late stages of grain filling in Huanghuaihai and Lower Yangtze regions . According to the rainfall and irrigation data for southern Huanghuaihai and Southwest China, conditions were conducive to wheat yellow rust and sheath blight dispersal. In northern Huanghuaihai, high temperature and low precipitation provided conditions conducive for wheat aphid reproduction.

The mid-May distribution of wheat yellow rust is shown in figure 4.6 and table 4.2. The total area affected by the disease reached 3.7 million hectares, with it severely affecting central Ningxia, most of Henan, central Anhui, and central Shandong, but only moderately impacting eastern Gansu, eastern Anhui, and southern Jiangsu.

Figure 4.6. Distribution of wheat yellow rust in China (mid-May 2017)

Table 4.2. Statistics of wheat yellow rust in China (mid-May 2017)

Wheat sheath blight—with distributions shown in figure 4.7 and table 4.3—damaged around 8.7 million hectares in China. The disease was found in most of Ningxia, most of Henan, and in central Anhui where impact was severe. In most of Shandong, eastern Gansu, southern Jiangsu, and eastern Sichuan, damage remained moderate.

Figure 4.7. Distribution of wheat sheath blight in China (mid-May 2017)

Table 4.3. Statistics of wheat sheath blight in China (mid-May 2017)

Finally, wheat aphid (figure 4.8 and table 4.4) damaged around 12.7 million hectares, with the pest occurring in most of Henan, northern Shandong, and most of Heilongjiang with a severe impact. In northern Anhui, eastern Gansu, most of Yunnan, and eastern Sichuan, the impact was only moderate.

Figure 4.8. Distribution of wheat aphid in China (mid-May 2017)

Table 4.4. Statistics of wheat aphid in China (mid-May 2017)

Table 4.2 

Table 4.3 

Table 4.4