During the rapeseed cultivation process, everyone should do a good job in prevention work to prevent pests and diseases. The peak period of rapeseed pests and diseases is mainly in the spring of the second year after the rapeseed is planted, when the growth is rapid. Therefore, in this period, if no pests and diseases are found, it is very important to take preventive measures and find timely response measures.
1 Main types and characteristics of rapeseed pests and diseases
1.1 The main types of diseases
1.1.1 Sclerotinia
Sclerotinia sclerotiorum can be infected in rapeseed from the time of emergence to maturity, especially when the flowering period is just completed. Sclerotinia sclerotiorum is harmful and has a wide range. The rapeseed organs including stems and mosaics are likely to be infected.
In the early stage of Sclerotium disease infection, plaques with a light brown color appear on the surface of the disease-infected part, which changes to grayish white over time. If the moisture content in the field is too large, the infected part will be ulcerated, and the surface of the ulcerated part will grow a white mold layer. After the stem is dried, the surface layer will be cleft.
1.1.2 Downy mildew (viral disease)
Downy mildew and sclerotinia disease are different, and the infection conditions are slightly more restrictive. It mainly occurs when the weather in the field is high due to weather such as rainy days. The rapeseed infected with downy mildew showed the phenomenon of leaf lesions, which showed that the front of the leaves would produce grayish white or light yellow, irregularly shaped irregular spots around the color between yellow and green. Once a lesion appears on a leaf, it shows a trend of interconnection. In the later stage of the deterioration of the disease, there will be cases where the local diseased leaves die or expand to the entire blade.
1.2 The main types of pests
Insect damage is different from disease damage, and the disease manifests itself in the diseased leaves and damages the whole leaves. The insect damage is directly caused by the loss of the blade. The pests in rapeseed planting mainly include aphids and green worms. In addition, locusts and beetles have a great influence on rapeseed. Here, only aphids and green worms are used as examples.
1.2.1 Locust
Rape aphids are basically distributed in the main production areas of rapeseed in China. Aphids are more prevalent in dry conditions in winter or in areas where there is a lack of effective watering and low moisture content. These areas are also more severe. The rapeseed twitching period and maturity period are the main damage period of the larvae. The locusts will bite the younger parts of the rapeseed tissue, causing damage to the leaves and leaving their own secretions to have a great negative impact on their normal growth. More importantly, aphids are often the spreaders of viral diseases. After being bitten by aphids, rapeseed is inhibited by the remnants and is also infected with viral diseases, causing extremely serious losses.
1.2.2 Green worm
The larvae of the larvae eat canola, and the degree of foraging varies with age. The 2nd instar larvae only feed on the leaves, while the 3rd instar worms bite the leaves of the whole rapeseed. Therefore, if the insects cannot be prevented in time, the total loss of rapeseed will be greatly caused. Similar to aphids, the feces of the larvae can also have a negative effect on the growth of rapeseed, threatening its growth.
2 Main factors affecting rapeseed pests and diseases
1) Weather. For example, when the spring and autumn are relatively dry, it is prone to pests, and too much rainy weather will easily aggravate rape disease.
2) Rainfall. The amount of rainfall is a direct factor affecting the size of the humidity. If the rainfall is suitable, the damage is small. If the rainfall is too much or too little, it will lead to pests and diseases.
3) Humidity and temperature. Excessive humidity leads to the spread of pests and diseases. If the temperature is too high, it will easily lead to a decrease in humidity, resulting in serious pests and diseases.
3 Corresponding control measures for rapeseed pests and diseases
3.1 Prevention and treatment measures for sclerotinia
1) Treat the root system. In order to effectively ensure or accelerate the growth and development of the roots of rapeseed plants, and at the same time effectively prevent the occurrence of lodging, the growers need to cultivate the soil 2 to 3 times while the rapeseed is in the full bloom period. This can not only promote the development of rapeseed, but also play a preventive role.
2) Pay attention to drainage work. Ensure that the drainage system in the field is functioning properly and in good condition. Only the drainage is good to ensure the respiration of the rapeseed between the soil and the further extension of the root.
3) Fertilization work cannot be ignored. It is necessary to properly control the proportion of fertilizers and supplement the fertilizers rich in phosphorus and potassium, so as to provide a guarantee for the robust growth and hard texture of rapeseed.
4) Pay attention to the pruning of the foliage during the growth of rapeseed, and do the trimming work such as removing the old leaves in time.
5) Do a good job in drug preparation during the period of rape blossoms. 50% carbendazim 800 times solution is a typical application agent.
3.2 Control measures against downy mildew
The prevention and control of downy mildew (viral disease) is similar to the prevention and control of sclerotinia.
1) Improve the field management in place, pay attention to the timely supplementation of potassium and phosphorus in the soil.
2) Due to the multiple conditions of downy mildew, it is necessary to drain in time in rainy weather or continuous rainy weather to prevent the growth of germs.
3) Downy mildew is also suitable for prevention and treatment with drugs. The main reagent for this disease is 69% Anke Mn-Zn wettable powder 600 times liquid.
3.3 Control measures against mites infection
For the control of locusts, the first thing to do is still the cultivating treatment. In the rapeseed period, rapeseed which has been infected by aphids is treated in time. After the planting work is completed, the chemical conditions can cover the soil. At the same time, we must pay attention to cultivating the soil before the flowering of the rapeseed, and determine that the rapeseed is planted at a reasonable density to ensure the transmittance of the growth conditions. When the number of aphids reaches the standard number of control, the breeder can use 50% anti-Citrus powder granules to control the drug at a ratio of 8 g per 667 m 2 . At the same time, on the basis of using it once every 7 days, it is used continuously for 1 or 2 times depending on the degree of spread of pests.
3.4 Control measures against green insect infection
Infected plants such as dead, old leaves and yellow leaves are removed in time to reduce the breeding grounds and edible resources of the caterpillars, and also reduce the risk caused by carrying the insects in certain leaves.
3.5 non-targeted prevention methods
In addition to specific targeted maintenance methods, there are several ways to improve the overall cropping effect.
1) Rationally planted according to soil conditions. Pay attention to the rationalization of planting intervals, rational fertilization and maintaining rotation to maximize the use of land while maintaining the nutrition of the land.
2) Do a good job in testing and emergency measures. Maintain daily monitoring of weather, humidity, temperature, and rainfall forecasts. At the same time, make emergency measures when there are excessive standards or emergency situations. How to remedy and prevent the next step is a problem that breeders must think about.
3) Dispose of rapeseed seeds before planting. Seeds that are disease-free, harmless, and stress-resistant after testing are selected before sowing. At the same time, the external surface must also ensure that it has no damage and the shape of the particles is full. It should be noted that the seeds are soaked with salt water before picking to remove the poor quality seeds. On the basis of good seed treatment, the sowing time also needs to be fixed in mid-September, supplemented by good agricultural measures to improve the survival rate of rapeseed and achieve superior seeding.
The above is the main types of pests and diseases of rapeseed and their control techniques. Farmers in need can refer to the technical content and provide more professional technical knowledge!
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