Causes and control strategies of wheat scab in China

Wheat scab is a climatic disease commonly encountered in our province. It caused devastating disasters in the 1980s, especially in the Jianghan Plain and the Edong River along the Yangtze River. The average outbreak occurred every 2 to 3 years. In the year of occurrence, the average field yield is reduced by 10% to 20%, and the severe field is reduced by more than 50% until the harvest is over. In recent years, the phenomenon of northward expansion of the disease is obvious, and the frequency of recurrence of the main wheat producing areas in northern Hubei has increased significantly, posing a greater threat to the production of summer grain. 2016 is a strong El Niño year. Since April, the rainfall has been frequent, which is very conducive to the repeated infection of wheat scab. Although it is actively organized and controlled, wheat scab is still in the main wheat area.

1 Occurrence

In 2016, wheat scab disease occurred and local epidemics occurred. According to the survey statistics of May 9th, the area of ​​scab in the province was 966,700 hm2, and the Jianghan Plain and the Edong Wheat Region were heavy. The average disease rate of the field was 30% to 40%, and the disease grain was 15% to 20%. The preliminary calculation of the damage loss rate is 5% to 6%; the northern Hubei wheat area is relatively light, the general field disease disease rate is 20% to 30%, and the disease grain rate is about 8%. The preliminary measurement damage loss rate is 2%~3. %. In addition to the impact on yield, wheat scab also affects food safety, and the bacterium produces vomiting toxins. Once humans and animals eat safely over-standard wheat products, they may cause dizziness, fever, vomiting, diarrhea and other toxic reactions.

2 Cause analysis

There are four main reasons for the recurrence of wheat scab in our province this year:

2.1 High bacterial source base

Wheat scab is one of the most common diseases in our province, which occurs every year. In particular, the Jianghan Plain and the Edong River along the Yangtze River have a perennial degree of above grade 4, and each year has a high bacterial source base. Bacterial source conditions.

2.2 Weather conditions are favorable for the occurrence of disease

According to meteorological data, there are 6 obvious rainfall processes in our province from April 1 to May 9. The rainy days in the main producing areas of Hubei, Edong and Jianghan Plains are as long as 15 to 19 days, 5~ more than normal. On the 7th day, the rainfall period in mid-April coincided with the height of wheat heading and flowering, which was very conducive to the initial infection of the pathogen. The rain from late April to early May was conducive to the repeated infection of the disease.

2.3 Poor resistance of main varieties

The wheat in our province is mainly composed of Zhengmai, Emai, Quino and Yumai. Among them, Zhengmai, Yumai and Quinoa are highly susceptible to scab, and the wheat varieties are generally moderate and resistant to scab. Sex is not strong. The Yangmai and Ningmai varieties with good resistance to scab are rarely planted in our province.

2.4 Weather conditions have a great impact on prevention and control work

The key prevention and control technology of wheat scab is to prevent the prevention of heading and flowering. Generally, the medicine is generally prevented once in the wheat spike. If the heading flower encounters rain, it must be prevented in the rain stop. The technical requirements for prevention and control are relatively high and difficult. Affected by the super-strong El Niño phenomenon, the frequent rains during the period of wheat heading and flowering in our province in 2016 are not conducive to the organization's prevention and control work. In some places, although the weather control was carried out in the rain stop interval, because of the short rain stop time, the rainwater washing effect behind it affected the early application and control effect.

3 prevention and control measures

In the prevention and control of wheat scab, it is necessary to fully implement the plant protection policy of “prevention first and comprehensive prevention”. In the prevention and control organization, it is necessary to embody the characteristics of “government-led, departmental cooperation”, and it is recommended to prevent and control wheat scab. Do the following:

The first is to breed and promote disease-resistant varieties, and to solve the problem of difficult control of wheat scab from the source.

The second is to strengthen cooperation with the meteorological department, closely monitor the weather changes in the wheat areas from the end of March to the middle of April, and do a good job in early warning and monitoring of diseases.

The third is to do a good job in the protection of the medicine during the heading and flowering period. In the wheat stalk, the high-efficiency agents such as cymene, prochloraz, tebuconazole and thiram are generally used for prevention once. If the rain is encountered during the heading and flowering period, it is necessary to catch up and prevent the rain during the rain stop.

The fourth is to grasp the rule of defense. The prevention and control of wheat scab is short-term and the task is heavy. It is necessary to increase investment, make full use of specialized and unified defense organizations, vigorously promote the work of unified prevention and control, and improve the efficiency of prevention and control.

The fifth is to strengthen the construction of agricultural infrastructure. Improve irrigation and drainage systems, reduce groundwater levels, and create environmental conditions that are detrimental to wheat scab.

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