With the arrival of spring, rape flowers have also quietly bloomed, but under this beautiful spring scenery, farmers cannot relax. Because there is a small insect that can cause a serious blow to the rape field, it is an aphid. The author borrowed some information, in North China, as a common pest of rapeseed, aphids can multiply for more than 10-20 generations in a year, the Yangtze River Flow City can reach 31-34 generations, and South China up to 46 generations. In the north of North China, aphid eggs will be stored on vegetables for wintering, and will hatch as dry mothers in March and April of the following year, and the insect pests will begin to erupt in mid-May, which is extremely harmful. Prevention at this time can reduce losses, so it is necessary for vegetable farmers to master control techniques to reduce the impact of insect pests.
Today, I want to understand with you why aphids occur, how they harm rapeseed, and how we should deal with insect infestations in rape fields.
(1) Life habits
Aphids feed on sap suckers, and the main gathering places are the flower shafts, leaf backs, stems and branches of rapeseed, and cabbage hearts. The growth of rapeseed is unbalanced, the growth of its young stems and flower shafts will stagnate, and the number of flowers and siliques will be reduced, which will eventually cause the growth of rapeseed to slow down to death. Aphids can excrete a large amount of honeydew and moisture, and the lower leaves are affected by it, and viral diseases occur, dry matter accumulation is reduced, and physiological functions are impaired." Aphids have the habit of migrating and spreading, and can constantly find new plant hosts, which will accelerate the spread of the virus and cause large-scale damage to rapeseed.
(2) Occurrence environment
The arid, warm climate favours aphid occurrence. The main breeding period of aphids is the mild climate of spring and autumn, and the most serious periods are autumn and late spring and early summer. Aphids have a strong reproductive capacity and there is a significant phenomenon of generational overlap. When the temperature stabilizes above 12c and lasts for 5 days, the aphids begin to multiply. The reproduction of a single female aphid can break through 100, with an average population of 70-80. In early spring and late autumn (the temperature is not high, a breeding generation of aphids takes 10 days, but this process can be shortened to 4-5 days in summer. The optimal breeding temperature for aphids is 16-22 degrees, and if combined with dry conditions, their occurrence area will continue to expand.
(3) Harmful diseases
The presence of aphids can lead to the destruction of rapeseed cells. After aphid infestation, the leaves of rapeseed will turn yellow and curl, showing a state of poor growth. After the flower stem and young stem are damaged, deformity will occur, which will adversely affect the extraction, flowering and fruit of rapeseed. Aphid-borne viral diseases will greatly inhibit the normal growth of rapeseed, its yield will be greatly reduced, and the quality of dishes will also be greatly reduced.
2.1 Agricultural control
(1) Variety selection With the progress of agricultural technology, there are more and more varieties of rapeseed, and its insect resistance function is also enhanced, when planting, it is necessary to keep the soil moist and choose insect-resistant varieties.
(2) Booby trap aphids: yellow is attractive to aphids, rapeseed seedling stage, you can put the "yellow plate" at the edge of the ground 0.5m above the ground, the yellow plate is a kind of plastic film, coated with gold pigment, and then brushed with a layer of motor oil or van tulin, you can trap the winged aphids 2
2.2 Physical control
(1) After the rapeseed seeds are sown, they can be covered with medicinal soil to provide a good protective environment for the development of seeds.
(2) Remove weeds in the field, especially the part around the buds, and cut off the feed source of the aphids.
(3) Timely cultivation of soil, do a good job of inter-seedling and seedling fixing, remove aphid plants, and prevent the migration, spread and reproduction of winged aphids.
(4) Determine reasonable dense planting, ensure that the ventilation and light transmittance of the field are good, transplant the seedlings with excessive density, and apply insecticides to them before transplanting to prevent the spread of aphids.
2.3 Chemical control
(1) Seed treatment: In order to achieve aphid prevention at the seedling stage, the seeds can be treated with drugs, including insecticidal phosphorus, aphid pine wettable powder, etc., a certain proportion of the drug is mixed, or high-quality hybrid rapeseed seeds are purchased to plant, thereby inhibiting the breeding of aphids.
(2) Seedbed stage: During this period, the leaves are tender green, the resistance is poor, and they are most susceptible to aphids. For spray control, 1.8% Avi* perchlorinated emulsion or 1.19% toxicity 1000 to 2000 times liquid, sharp red wettable powder 1000 times liquid, 37% high hydromalacion 1000 to 2000 times liquid, 2.5% so kill emulsion 3000 times liquid. If rapeseed needs to be transplanted, it needs to be sprayed two days in advance of this ratio, one time, to avoid carrying aphids into the field.
(3) Overwintering period: Aphids need to lurk in rape plants for wintering, such as aphids, wingless aphids and other radish aphids like to hide in the heart of the vegetable, while peach aphids usually hide in the back of the leaves near the ground, these hidden aphids will erupt in the spring. Therefore, the control of aphids needs to be treated during the overwintering period, and the specific measures are: spraying 25% fast killer (octyl chloride) emulsion 1250 times liquid, 5% Ruijinte emulsion 2000 industry 2500 times liquid, 50% malathion emulsion 800 times liquid, 40% rapid killing emulsion 4000 times liquid, 2.5% enemy killing emulsion 4000 times liquid, 10% annihilation (permethrin) emulsion 2500 to 4000 times liquid.
(4) Tomb extraction period: The harm of aphids is centered on the buds of the main branch and spreads to the branched carobs, peduncles and flower buds. In the base extraction period, it must be treated fiercely. In the early stages of the main branch of rapeseed, it can be sprayed with a spray treatment solution material of water, washing powder and urea, and the capacity is divided into 100 kg, 0.5 kg and 1 kg.
(5) Flowering horn-bearing period: Rapeseed is harmed by aphids during the flowering corner-bearing stage, and there may be a phenomenon of dry diamonds, or it may only flower without cornering, and the fullness of carobs is not high, which will directly affect the total yield of rapeseed. This period requires heavy treatment of aphids and suppression of aphids during the initiation of harm to avoid their full dryness. When treating aphids, 20% rehabilitation polyhydrous solvent 5000 to 6000 times liquid, 2.5% kung fu emulsion 2000 to 3000 times liquid, 25% Baode emulsion 1500 to 2000 times liquid, 25% Aktai water dispersible granules 6000 to 8000 times liquid, 48% Lesben emulsion 1000 to 1500 times liquid, 40% Xinyibao emulsion 1000 to 2000 times liquid for spray treatment.
2.4 Biological control
The main way to achieve biological control is to use the natural enemies of aphids, including ladybirds, aphid cocoon bees, aphid-eating flies, grasshoppers and so on. On the one hand, these natural enemies should be protected, and on the other hand, the natural enemies of aphids can be bred in captivity and released to the park.
At present, there are many ways to control rape aphids, and when the disease is serious, it is mainly based on pharmaceutical control, and the administration of drugs should be based on the number of aphids, so as to avoid excessive medication so that the quality of vegetables is the most damaged, which is not conducive to human consumption. So it seems that it is best to control the aphids before they have begun to form a scale, so as to avoid the pollution of pesticides, readers and friends we are here today, we will see you in the next issue.