Prediction and control of diseases and insect pests of Ermai in Shanghai

According to the occurrence base of diseases and insect pests of two wheat crops in various districts (counties), combined with the analysis of weather conditions, it is expected that the occurrence trend of diseases and insect pests of two wheat crops in this city will be moderate this year. Among them, scab occurred moderately and locally heavily, gray planthopper occurred heavily, wheat aphids occurred moderately, wheat powdery mildew and barley scab occurred lightly, and armyworm occurred lightly. In order to effectively control the damage of diseases and pests and seize a bumper harvest of summer crops, it is hoped that all districts (counties) will conscientiously do a good job in the prevention and control of diseases and insect pests of summer crops in the light of their respective production practices.

I. Analysis of occurrence trend

(1) scab

1. Occurrence degree

The occurrence of wheat is moderate, the natural diseased ear rate is 13.18%, the heavy field is more than 20%, the barley is moderate to light, and the natural diseased ear rate is 715%.

2. Forecast basis

(1) bacterial source: Rice pile vesicle was found on March 20 (Qingpu and Jiading) and in other districts (counties) on April 5. The occurrence period was delayed by more than 10 days compared with the perennial March 10. On April 14, the carrying rate of rice pile vesicle hole was 22%, the rate of diseased plant was 4.43%, and the ascomycete maturity index was 41.25%. The peak of ascospore release was expected to be on April 20-25, which coincided with the heading stage of wheat and some late barley.

(2) Weather: according to the forecast of the meteorological department, from April 20 to May 20 this year (from flowering to late filling stage of wheat), the total rainfall was 101.5 mm, with a range of 73 mm 130 mm, slightly less than the annual rainfall of 137.6 mm, with rain days of 11.5 days. it is basically similar to the 12.9 days of the year. There are 4-5 days of warm and humid weather from late April to mid-May, which is beneficial to the occurrence of scab.

(3) Ermai varieties and their growth trend: this year, the planting area of wheat in the city is about 800000 mu (including Farm Bureau), of which 670000 mu are wheat. the main varieties are Yangmai-158,Yangmai-11, Yangmai-12, Yangmai-15, Yangmai-16, Jiamai 1 and Luomai 8, all of which are moderately resistant to scab. The planting area of barley is 130000 mu, and the main varieties are Hua 22, Hua 30, Rudong 7, Shenmai 1 and Humai 16. According to the investigation of seedling situation in early April, the growth period of wheat this year was 7 days later than usual, in which barley began to spike at the beginning of April and reached full heading before April 10; wheat began to spike on April 12, reached full heading around April 20, and entered the flowering stage (susceptible period) from April 23 to 26.

(2) Gray planthopper

A total of 576 fields of wheat, oil, grass, green manure and rice piles were surveyed from March 26th to 28th, with an average of 13600 insects per mu, ranging from 0.13 to 52500, which was lower than 17300 in the same period in 2006 and 51000 in the same period in 2007. A total of 362 fields of wheat, rape, weeds and green manure were surveyed in 10 districts and counties in the city on April 14, with an average of 20600 insects per mu (48700 in the same period last year). It is estimated that the egg incubation period of the first generation of gray planthopper will be around April 25, and the number of eggs per mu will be 25 ~ 400000, with a moderate to large occurrence degree.

(3) wheat aphid

According to the systematic investigation of wheat aphids by plant protection stations in various counties (districts), on April 14, the average rate of aphids was 9.33%, with a range of 2.0-12.0%, and the number of aphids per 100 plants was 38.0, with a range of 14.0-98.0, slightly less than 165 in the same period of previous years. It is expected that after wheat heading, the wheat aphid will increase obviously with the increase of temperature, and the occurrence degree will be moderate.

(4) powdery mildew

Wheat powdery mildew was found on April 5, which belongs to the year of late onset. The average rate of diseased plants in the area on April 14 was about 20%, with a maximum of 31%. With the increase of temperature, it is expected that the increase of powdery mildew will accelerate from late April, and the occurrence degree is moderate to mild.

II. Opinions on prevention and control

At the heading stage of wheat, the focus of control is wheat scab, as well as gray planthopper, wheat aphid and powdery mildew. The main purpose of controlling gray planthopper is to effectively reduce the field base of gray planthopper in wheat field and reduce the migration of the first generation of gray planthopper to paddy field as much as possible.

1. Medicament selection: (1) 105 grams (1.5 packets) of 25% chlorpromazine wettable powder per mu + 20 grams per mu of pyrazidone wettable powder. (2) 105 grams (1.5 packets) of 25% chlorpromazine wettable powder per mu + 40 grams of 10% imidacloprid wettable powder and 50 kg spray on water. To control armyworm, 25% Kuaishaling (Xin, cyanide EC) can be used to control armyworm with 100 ml per mu. For some varieties susceptible to powdery mildew, powdery mildew should be added separately.

2. the appropriate period and times of control: the control of scab should be fully applied once from full heading to the early flowering stage, about April 20-26, and then the second control should be carried out according to the weather trend and the occurrence of gray planthopper in the field. It is necessary to ensure secondary control in the late growth green and high-yielding areas.

3. In case of continuous overcast and rainy weather in the appropriate period of prevention and control, we should seize the sunny day and do not miss the appropriate period of prevention and control.

Matters needing attention:

1. Organophosphorus pesticides should be used cautiously in the areas of releasing bees, @ # @ 234 pesticides and @ # @ 235 pesticides.

2. The liquid should be sprayed to the whole plant when applying.