It is reported that in 2019, corn armyworms are large-scale infested, and corn armyworms in Hanchuan, Tianmen, Jiayu and other places in Hubei have occurred, and some areas are seriously harmed. So what are the occurrence rules of corn armyworm in 2019? Are corn armyworms harmful? How to control corn armyworm? Let's take a look.
2019 corn armyworm occurrence law
Corn armyworm is a long-distance migratory pest. There is no diapause, as long as the conditions are suitable, continuous breeding can be carried out. In my county occurs 3 generations a year. Every spring, it is moved in from the southern provinces to harm the wheat in the jointing and pregnant ear stage. The second generation of armyworms is harmful to summer corn, and the peak period is in mid-to-late July, and the peak period of the third generation of armyworms is in mid-to-late August.
In autumn, as the temperature drops, the corn armyworm migrates back to the south with the high-altitude air currents. In natural terms, the first generation of eggs is 6-15 days, followed by 3-6 days each, the larval stage is 14-28 days, the pre-pupal stage is 1-3 days, and the complete generation is about 40-50 days. Larvae often migrate in clusters, mostly early and late active adults, i.e., before sunrise in the morning to 10 a.m. and around evening. Adult insects have strong flight ability, have the characteristics of long-distance migration as a pest, day and night out, have a strong tendency to sweet and sour liquid and black light, mostly lay eggs in the middle and lower part of wheat dry yellow leaf tips, leaf sheaths, and lay 1000-2000 eggs by single females.
2019 corn armyworm harm symptoms
Corn armyworm is an explosive and devastating pest, commonly known as marching insect, shaving insect, night thief insect, five-flower worm and so on. Influencing crop food yields are the larvae of the armyworm, a predatory pest that can eat up crop leaves and bite off crop ears, causing serious yield reductions.
The larvae are 6 years old, and the 1st to 2nd years old are mostly hidden in the new leaves or leaf sheaths of the crop to eat for harm, eating day and night, but the amount of food is very small, nibbling on the leaf flesh, leaving the epidermis, resulting in translucent small stripes.
Larvae above 3 years old show irregular lack of moments after infestation of leaves, and when overeating, they can eat all leaves. When the large occurrence, the corn leaves are eaten up, leaving only the leaf veins, resulting in a serious reduction in yield, or even a harvest failure, and the resistance to drugs is about 10 times stronger than that of 2 to 3 years old.
Therefore, the best control effect is before 3 years of age, because the resistance of armyworms is the weakest at this time. This feature can be used in prevention and control to improve the effectiveness of prevention.
Corn armyworm control technology
Since maize armyworm is an "outbreak" pest, the control of maize armyworm should be based on comprehensive monitoring and integrated control measures.
1. Agricultural control
1) Timely morning seedlings, fixed seedlings
The seedlings should be early, and should be selected before the seedlings will take root, generally in the seedlings with 3 to 4 leaves. The principle of inter-seedlings is to remove weak seedlings and keep strong seedlings; to remove miscellaneous seedlings, to leave seedlings and seedlings of the same color; to go to sick seedlings and leave healthy seedlings.
2) Deep pine before shoveling, shovel in time
After the emergence of seedlings, carry out deep pine before shoveling or ploughing before shoveling. If no chemical herbicide is used, after the head is shoveled, it is shoveled once every 10 to 12 days, so that three shovels can be done three times; the use of herbicide can be used twice.
3) Topdressing early
Maize is carried out at the 7-9 leaf stage or before jointing, and the total nitrogen fertilizer amount of topdressing is 75%-80%, and the topdressing site is 10-15 cm away from the plant and the depth is 8-10cm.
4) Timely weeding
Weeding work should be carried out well, and the shortage of grass should be controlled to avoid the occurrence of drug damage. For plots where pre-seedling chemical weeding has been carried out, it is not recommended to use post-seedling chemical weeding again, and to control grass pests with agronomic measures such as shoveling. For plots with good chemical weeding effect and no grass shortage, it is also necessary to do a good job of shoveling, warming the living soil, and chemical safety weeding can be carried out on the plots with serious grass shortages, and the choice of nicosulfuron + adiposelide or nilfonyl ketone or methisulfonone, in the corn 3 to 5 leaf stage, try to avoid the use of 2,4-D butyl ester. Varieties that are more sensitive to nicosulfuron can be controlled with benzazozone + indezin.
2. Biological control
The biological control mentioned here refers to the use of biological agents for control, and the young larvae stage uses 25% urea No. 3 suspension agent 750mL/hm2, and uniformly sprays the water 450kg/hm2, which not only protects natural enemies, but also is safe for crops, and the amount is small and does not pollute the environment.
3. Physical prevention and control
1) Booby trap adults
Use the phototropism of adult insects to trap adult insects with black light; sweet and sour solution to trap adult insects, use sweet and sour liquor or other fermented sweet and sour foods to form a certain proportion of the lure, and then add a small amount of enemy insects, and put the lure into the basin. Open the lid every evening, place the enticing solution at the ground between the fields, and the next morning retrieve the pot to remove the moth and cover it to prevent the enticing solution from evaporating. Add a lure once every 2 to 3 days, change it once every 5 days, and continue for 16 to 20 days.
2) Grass handle to lure eggs
Armyworms like to lay eggs on yellow dry grass. Therefore, it is better to bundle the straw loosely into a small handle of 5 cm in diameter, insert it in the corn field, higher than the plant, and spray the sweet and sour liquid on the grass handle. Change it once every 5 to 7 days, and the grass that is replaced will be burned in a concentrated manner. All moths, eggs near sweet and sour pots, grass handles, spray medicine every 7 days to kill the larvae hatched by the eggs.
4. Chemical control
1) Poison bait booby traps
Use 90% of the insects 1500g/hm2 pairs of water, mix on 22.5kg/hm2 stir-fried bran to make poisonous bait, and spread along the corn line in the evening to booby trap. You can use a plastic or iron drum to drill several sieve holes in its bottom with local materials. Put it on a trolley and sprinkle as you go.
2) Foliar spray
Before the age of the insect, 2.5% cypermethrin emulsion or 4.5% high-efficiency cypermethrin 300~450mL/hm2 was used; at 3-4 years of age, 48% chlorpyrifos 225~300mL/hm2 or 0.5% methyl vitamin salt 450~600mL/hm2 was uniformly sprayed with water 450kg/hm2. Weeds in the fields and on the roadsides are sprayed. At the same time, the field with a large amount of insects can first pat the plant to shake the armyworm to the ground, and then spray the ground to receive good results; the application time is best selected in the morning or evening to improve the quality of prevention and control.
3) Sprinkle poisonous soil
Use 40% octylthion emulsion 1125 ~ 1500g / hm2 to add water in an appropriate amount, mix sand soil 600 ~ 750kg / hm2 sprinkling, can protect natural enemies, but also can prevent corn borer. The humidity of the toxic soil should be moderate, and there is a criterion for judging that the hand is kneaded into a ball and scattered on the ground. Generally to the hand kneaded into a ball, the hand can be naturally dispersed after loosening as well, too dry is easy to cause dust flying, too wet if it is uneven, affecting the efficacy.
The above is the 2019 corn armyworm occurrence law, hazard symptoms and prevention and control technology introduced by the small editor of agricultural materials for everyone, if you want to know more about corn planting technology, you can pay attention to: WeChat: huobao3456tv learn more, after paying attention, you can also leave a message to reply to the plant protection information you want to know.