Forecast of Major Crop Diseases and Pests in China in 2016
On December 15-16, 2015, the National Agricultural Technology Center organized a meeting of testing and reporting personnel and relevant experts from various provinces (districts, cities) to discuss the trend of major crop diseases and pests in 2016. Due to factors such as a high incidence base of pests and diseases, favorable winter and spring climate, and crop cultivation, it is expected that major crop diseases and pests in China will be more severe in 2016, with a cumulative occurrence area of about 5.5 billion acres nationwide. Among them, the risk of recurrence of epidemic and migratory diseases and pests such as wheat scab, armyworm, and rice "two migratory" pests is higher than that of the previous year. Rice sheath blight, rice borer, wheat aphid, and corn borer occur in a wide range of areas and are severely affected. Rice blast, wheat stripe rust, corn leaf spot, and potato late blight may occur in some areas, while locusts and grassland borers generally occur steadily.
1、 Rice "Two Migration" Pests
According to monitoring, the number of "two migration" pests returning in autumn 2015 was relatively high, with an average of 8% higher than usual in the middle and lower reaches of the Yangtze River, Jiangnan, and South China rice areas under light traps. According to the monitoring and prediction of the National Climate Center, as of December 26th, the cumulative sea surface temperature anomaly was 23 ℃, and the maximum monthly sea surface temperature anomaly reached 2.3 ℃, making it the second strongest El Ni ñ o event in history and will continue until the spring of 2016. Research has shown that the year in which El Ni ñ o occurs and the following year are often the years with high incidence of rice diseases and pests. This El Ni ñ o event will lead to normal or high winter and spring temperatures, excessive precipitation, early flood season, and uneven spatiotemporal distribution in the southern rice region. These climate conditions are conducive to the overwintering and accumulation of pests in China and Vietnam, increasing the occurrence base, and also leading to an earlier migration period of pests, an increase in migration volume, and localized concentrated landing damage. The mixed cultivation of single and double cropping rice in southern China is mainly characterized by coarse stalks, large panicles, high-quality and high-yield varieties, which can easily form a field microclimate suitable for temperature and high humidity. Moreover, the planting and growth periods are irregular, and there are many bridge fields, which is conducive to the "two migration" of pests and exacerbates the damage.
It is expected that in 2016, rice planthoppers will generally occur in a heavy to severe manner, with a significant increase in severity compared to recent years, covering an area of 430 million mu per occurrence. Rice fields in South China, Jiangnan, and the middle and lower reaches of the Yangtze River will experience a significant outbreak, while rice fields in Southwest China and Jianghuai will experience a significant increase. The overall occurrence of rice leaf roller is relatively heavy, with an area of 320 million mu per occurrence. It occurs extensively in the eastern Guizhou, western Hunan, Jiangnan, and the middle and lower reaches of the Yangtze River, as well as in the rice areas along the river. It is moderate in most rice areas in the southwest.
2、 Rice sheath blight
The main rice producing areas in China suffer from sheath blight, which occurs year after year. The number of bacterial sources in the fields continues to accumulate, and most rice areas have a moderate or higher degree of occurrence of bacterial sources. It is predicted that in the winter of 2015 (from December 2015 to February 2016) and spring of 2016 (from March to May), the temperature in the southwest, Jiangnan, and South China rice regions will be higher and the precipitation will be higher. At present, most of the high-yielding varieties with coarse stems and large panicles planted in various rice regions in China are susceptible varieties. The temperature and humidity conditions and planting system are suitable for overwintering and disease prevalence of rice sheath blight in the main rice production areas.
It is expected that rice sheath blight will occur in a severe to severe manner in 2016, covering an area of 270 million acres. It will occur extensively in the rice regions of South China, Jiangnan, and the middle and lower reaches of the Yangtze River, with a heavy incidence in the southwest northern and Jianghuai rice regions, and moderate incidence in the southwest southern and northeast rice regions.
3、 Rice borer
According to the pre winter survey, the area and base number of the overwintering pest sources of the Chilo suppressalis in 2015 were on the high side, and the area of the national pest sources increased by 10.8% compared with 2014. The number of live pests per mu in most rice areas in southern South China, Jiangnan, the middle reaches of the Yangtze River, and northeast China was 2500-5000, of which the number of live pests per mu in Jiangxi and Heilongjiang increased by 34.8% and 65.9% year on year, with a base number of pest sources that emphasized the occurrence degree above. It is predicted that in the winter of 2015, there will be a trend of higher temperatures and less precipitation in the central and southern regions throughout the country. The temperature and humidity conditions are suitable for the overwintering of rice borers in the main rice producing areas. The main rice producing areas in China have a large harvest area, high residual rice piles, and a high proportion of coarse straw varieties, which are conducive to the overwintering, occurrence, and reproduction of rice borers.
It is expected that the overall occurrence of rice borers will be moderate in 2016, with an area of 280 million mu per occurrence. Among them, the occurrence of rice borers will be more severe in the mixed cropping areas of single and double cropping rice in Jiangnan and the middle and lower reaches of the Yangtze River, as well as in the rice areas in the northern southwest; The occurrence of the rice borer is moderate in the southern and southwestern northern rice regions; The rice borer is showing an upward trend in some rice areas in the middle and lower reaches of the Yangtze River.
In 2015, the damage level of the third generation armyworm was significantly higher than that of the previous year, and some areas were more severe than in 2013, accumulating a large number of effective insect sources. In late summer and early autumn, high-altitude monitoring lights in Northeast China, North China, Huanghuai, the middle and lower reaches of the Yangtze River, Jiangnan, South China, and Southwest regions all attracted adult armyworms, with a relatively high amount of trapping in the year. In September, the cumulative number of insect traps was 1174 in Zhangwu, Liaoning, 2741 in Changling, Jilin, and 4941 in Luanxian, Hebei, respectively. It was 53649 in Changdao, Shandong, 250-870 in Mengzhou, Henan, Dongtai, Jiangsu, Anxian, Sichuan, Fengdu, Chongqing, Qianjiang in Hubei, and Zhijiang in Hunan. It was 60-140 in Baodi, Shandong, Laizhou, Wanrong, Shanxi, Fengxian, and Xiangshan, Zhejiang; The cumulative number of insect traps from September to November was 104 in Yizhou, Guangxi and 298 in Xiapu, Fujian, respectively. The number of insect traps at the above points is generally higher than in 2014. It has been proven that there is a significant positive correlation between the number of autumn migrations in that year and the number of spring migrations in the following year. The number of insect traps on Long Island in Shandong is the second highest since 2003, which is 28.3 times and 1.9 times higher than in 2014 and 2013, respectively; Zhangwu in Liaoning was 3.3 times higher than in 2013 (no worms were found in 2014), Luanxian in Hebei was 1.8 times higher than in 2014, Dongtai in Jiangsu, Fengxian in Shanghai, and Xiangshan in Zhejiang were more than 10 times higher than in 2014, and Xiapu in Fujian was 2.2 times higher than in 2014. It is predicted that in the winter of 2015, most of South China and Jiangnan will have normal temperatures and excessive precipitation; In the spring of 2016, the middle and lower reaches of the Yangtze River to the southern part of the Huanghuai River experienced excessive precipitation and temperatures close to normal, which was beneficial for the reproduction and occurrence of armyworm populations in winter and spring.
It is expected that in 2016, the occurrence of armyworm will be relatively severe, with an area of up to 100 million mu per occurrence. Among them, the risk of high-density damage to local fields of cereal crops, mainly corn, in the Huanghuai, North China, and Northeast regions is relatively high.
5、 Wheat aphid
According to the pre winter survey, aphids are common in the Jianghuai, Huanghuai, North China and Northwest wheat regions, and the occurrence area is the same as that in 2014; The average number of aphids per 100 plants in Anhui, Shanxi, Shaanxi, Henan, Beijing, and Shandong is 5-16, and 1-3 in Gansu, Hebei, and Ningxia. Compared with the same period in the year, Shanxi and Gansu have increased by 3% and 10% respectively, and most other wheat regions are similar; Most wheat areas have increased by 45% -200% compared to the same period in 2014. It is predicted that in the winter of 2015, most of the winter wheat areas in the Huanghuai, North China, and Northwest regions will experience higher temperatures than usual; In the spring of 2016, the temperature in most wheat areas was close to the same period as usual, while the precipitation in North China, the central and northern parts of the Huanghuai River, and most of the southwest was relatively low. The winter and spring climate was favorable for aphid overwintering and occurrence. In 2015, the planting area of winter wheat in China steadily increased slightly, and the seedling growth was good. The main varieties planted in the main wheat producing areas of Jianghuai, Huanghuai, and North China generally had poor resistance to aphids, which was conducive to aphid infestation.
It is expected that the overall occurrence of wheat aphids will be more severe in 2016, with an area of 260 million mu per occurrence. Among them, major outbreaks occurred in Shandong and Hebei, with a particular emphasis on other wheat regions in Sichuan, Ningxia, North China, and Huanghuai, while moderate outbreaks occurred in most of the wheat regions in the middle and lower reaches of the Yangtze River, as well as other wheat regions in the southwest and northwest.
6、 Wheat stripe rust
According to the pre winter survey, the area of wheat autumn seedlings in 2015 was small and the overall condition was mild. The main areas of autumn seedlings in northwest China, such as Gansu, Ningxia, Qinghai, and Shaanxi, have an area of 2.16 million acres, which is the smallest year since 2001. Single diseased leaves are mainly found in various regions, and there are many diseased centers in local early sowing wheat fields. The diseased areas in Gansu and Ningxia decreased by 12.0% and 56.8% year-on-year, with a general diseased leaf rate of 0.01% -6.5%, with a maximum of 30%. Nine counties in the Guanzhong region of Shaanxi, including Baoji and Xianyang, have seen the disease, with four more counties than in 2014, indicating an earlier occurrence year. Sporadic occurrences occur in three counties of Guangyuan, Mianyang, and Liangshan in Sichuan, belonging to early onset years. The disease is sporadic in Aksu, Xinjiang, with an average leaf disease rate of 1.3%, which is more severe than the same period from 2012 to 2014. It is predicted that in the winter of 2015, there will be more precipitation in the middle and lower reaches of the Yangtze River and the southwest wheat region, which is conducive to the winter propagation and spread of stripe rust; In the spring of 2016, the eastern part of the northwest region, the middle and lower reaches of the Yangtze River, and the southern part of the Huanghuai River received more precipitation, with most of Gansu, Ningxia, western Shaanxi, southern Shandong, southeastern Henan, and eastern Hubei receiving 20-50% more precipitation, which is very favorable for the spring epidemic of stripe rust. At present, most wheat varieties planted in China have poor rust resistance, especially since 2012, the new pathogenic group "Guinong 22" of stripe rust has risen to the dominant group in some regions such as Gansu and Sichuan, accelerating the loss of rust resistance in wheat varieties and exacerbating the disease.
It is expected that stripe rust will occur moderately in 2016, with an area of approximately 37 million acres. Among them, the Jianghan Plain in Hubei and its northwest, southern Shaanxi and western Guanzhong, Longnan and late maturing wheat areas in Gansu, along the river basin in northeastern Sichuan, southern Henan, eastern part of the Ili River Valley in Xinjiang, and some parts of the Tacheng Basin are particularly prevalent, while other wheat areas in southwestern China, most of Gansu, other parts of Shaanxi, most of Henan, southern Ningxia, eastern Qinghai, and other wheat areas in Xinjiang are moderately prevalent.
7、 Corn borer
According to a survey, the average number of live corn borers per 100 stems before winter 2015 was 50-75 in Liaoning, Heilongjiang, and Jilin, 31-38 in Shandong, Jiangsu, Henan, and Xinjiang, 17-28 in Yunnan, Hubei, Tianjin, Inner Mongolia, Hebei, Shaanxi, Chongqing, Hunan, Guizhou, and Anhui, and less than 10 in Shanxi, Beijing, Gansu, and Sichuan. Compared to 2014, Liaoning increased by 138%, Hebei and Shaanxi increased by 27% and 58%, Beijing, Shandong, and Henan increased by 7-12% respectively, and Tianjin increased by 2%; Other provinces such as Heilongjiang, Jilin, and Inner Mongolia are 10% -40% lower. In the winter of 2015, the temperature in the Huanghuaihai region was relatively high, which was beneficial for the overwintering of corn borers; In the spring of 2016, most of Northeast China experienced heavy rainfall and low temperatures, which were conducive to the concentrated emergence of the first generation of corn borer adults. Most regions such as Northeast and North China have poor resistance to corn borer, which is beneficial for the reproduction of corn borer populations.
It is expected that the occurrence area of corn borer in 2016 will be 350 million mu, with the first generation occurring more heavily in the Northeast and moderate in parts of North China, Huanghuai, and Southwest, with an occurrence area of 150 million mu; The second generation is particularly prevalent in Liaoning, Inner Mongolia, Xinjiang, and Yunnan, with a focus on the Northeast, North China, and Southwest regions
According to the survey, the area and density of East Asian migratory locusts and Xizang migratory locusts in 2015 were higher than those in 2014, while the area and density of Asian migratory locusts were lower. Among them, the area of autumn residual locusts of East Asian migratory locusts is 8.127 million mu, which is 2.3% and 7.9% lower than the average in 2014 and the past five years, respectively; The average density of residual locusts per acre is 10.7, which is 2.7% and 8.5% lower than the average in 2014 and the past five years, respectively. Tianjin, Hebei, Shandong, Henan, Shanxi, Shaanxi, and Hainan have all found high-density residual locust patches with over 100 heads per acre, covering an area of 108000 acres, an increase of 33.3% compared to 2014 and a decrease of 28.9% compared to the average in the past five years. The residual locust area of Xizang locusts in agricultural areas of Sichuan is 31000 mu, increasing by 6.9% and 24.0% respectively compared with 2014 and 2013. The average residual locust density is 6.8 per mu, slightly higher than the average in 2014 and recent years. The residual area of Asian locusts in 2015 was 214000 acres, a decrease of 28.7% compared to 2014 and a decrease of 43.9% compared to the average of the past three years; The average density of residual locusts per acre is 2.8, a decrease of 12.5% compared to 2014 and 39.4% compared to the average in the past three years. It is reported that in 2015, Asian locusts were prevalent in Kazakhstan, but to a lesser extent. Therefore, it is not ruled out that there is a possibility of foreign locust sources migrating into the country. Climate prediction shows that in the winter of 2015, the temperature in most parts of the Huang Huai River, North China and Inner Mongolia will be 1-2 ℃ higher, and the temperature in northern Xinjiang, Sichuan and Xizang will be normal, which is conducive to the overwintering of the three locusts; In the spring of 2016, except for the relatively low temperature in the northern part of Xinjiang, other locust infestation areas were normal or relatively high. Except for the southern part of the Yellow and Huaihe Rivers, most other areas had normal or relatively low precipitation, which was generally beneficial for the occurrence of locusts. The water level in some locust infestation areas of East Asia has decreased, and the suitable locust area has expanded. The ecological environment is also conducive to locust occurrence.
It is expected that the overall occurrence of East Asian locusts will be moderate in 2016, with high-density locust patches appearing in some areas such as Puyang, Xingyang, Jiaozuo, Dongming, Shandong, Nandagang and Haixing in Hebei, Beidagang in Tianjin, Ruicheng and Yongji in Shanxi, Dali in Shaanxi, and Dongfang in Hainan. The migratory locusts in Xizang occur moderately in most of the frequent areas in Xizang and Sichuan, while the Jinsha River, Yalong River, the Yarlung Zangbo River and other river valleys are partially prone to occurrence. The occurrence of Asian locusts is relatively mild, and it cannot be ruled out that there is a possibility of foreign locusts migrating into the country and causing harm. In some reed ponds and wetlands in Heilongjiang and Jilin, high-density community type locust patches may occur. The occurrence areas of East Asian migratory locusts, Xizang migratory locusts and Asian migratory locusts are 20 million mu, 1.6 million mu and 600000 mu respectively, and the standard areas are 12 million mu, 1.1 million mu and 400000 mu respectively.
9、 Grass moth
According to a survey, in 2015, the overwintering source of grassland moths was only found in 4 banners (counties) of 4 leagues (cities) in Inner Mongolia, such as Hohhot, Ordos, Bayannur, and Hulunbuir, as well as 2 counties (districts) of Shizuishan City in Ningxia. The overwintering areas of the two regions were 242000 mu and 36000 mu, respectively. The average density of overwintering live cocoons was 0.58 and 0.01 per square meter, respectively. Compared with the past 5 years, the total overwintering population in China was only higher than in 2011, far lower than in 2010, 2012, and 2013, and a decrease of 35.4% compared to 2014, It is still the lighter year since 2001. Overwintering insect sources were found in three counties (cities) in the Altay region and one county in the Hotan region of Xinjiang. The overwintering area is 83000 acres, and the average density of overwintering live cocoons is 0.05 per square meter. The total overwintering insect population is much lower than from 2010 to 2013, a decrease of 42.9% compared to 2014. It is reported that the grassland moths in Novosibirsk and Far East regions of Russia, which can provide insect sources for China, are also at a low point in their occurrence cycle. Climate prediction shows that in the spring of 2016, the temperature in most parts of the northwest and northeast regions was low, which had adverse effects on the growth of host plants, the emergence, persistence, reproduction of overwintering adults, and the occurrence of damage to first generation larvae.
It is expected that the first generation of grassland moths will occur lightly in the northwest, north China, and northeast of China in 2016, with an area of approximately 1 million acres. Due to unclear insect sources in Mongolia, Kazakhstan, and other regions, it is not ruled out that the concentrated migration of the first generation of adults may cause harm to the second generation of larvae.
10、 Climatic epidemic diseases
Scab, rice blast, big leaf spot, and late blight are the most severe climatic epidemic diseases of the four major grain crops in China, namely wheat, rice, corn, and potato. At present, most of the main varieties cultivated in China are susceptible or poorly resistant to Fusarium head blight. Except for wheat varieties such as Yangmai and Ningmai that exhibit good resistance to Fusarium head blight, the main varieties recommended in the middle and lower reaches of the Yangtze River, Jianghuai, Huanghuai, and North China wheat regions are susceptible to Fusarium head blight; The resistance of main rice varieties to rice blast varies, with susceptible varieties reaching 50% -60% in some regions of Sichuan, Chongqing, and Heilongjiang; The planting area of susceptible varieties in the main potato production areas is over 70%. Due to continuous cultivation, the variation of the pathogen population in disease-resistant varieties leads to weakened, degraded, and even lost resistance. Crops such as wheat and rice are planted across different regions, resulting in poor resistance performance. High fertilizer and water management in high-yield areas of crops leads to large populations and closed fields, which is also conducive to the occurrence and prevalence of diseases. In 2015, the winter wheat sowing date was postponed in the wheat regions of Jianghuai, Huanghuai, and the middle and lower reaches of the Yangtze River. The probability of encountering the susceptible period of Fusarium head blight with continuous rainy weather in the spring of 2016 increased, and some frequently occurring Fusarium head blight pathogens continued to develop resistance to commonly used pesticides, which would affect the prevention effect and exacerbate the prevalence of Fusarium head blight. Climate prediction shows that in the spring of 2016, the temperature in most wheat areas was close to the same period as usual. The precipitation from the middle and lower reaches of the Yangtze River to the southern part of the Huanghuai River was relatively high, with Anhui, Jiangsu, Shanghai, northwestern Zhejiang, eastern Hubei, southeastern Henan, and southern Shandong receiving 20-50% more, which is very beneficial for the epidemic of scab. Rice tillering and heading stage, wheat heading and flowering stage, corn jointing to heading stage, and potato flowering stage are susceptible to diseases
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