Control techniques of diseases and insect pests of scallions

Scallions are perennial herbs with cylindrical leaves, hollow in the middle, fragile and easy to fold, and cyan. In East Asian countries and Chinese regions, scallions are often eaten as a very common spice, condiment or vegetable, and play an important role in oriental cooking. The following editor will introduce the pest control techniques of scallions.

Brown spot of green onion

[disease characteristics] Welsh onion brown spot, also known as leaf tip verticillium wilt, mainly harms leaves, the leaf infection is easy to start from the upper, initially water-immersed yellow brown spots, and then generate fusiform disease spots, generally 10: 30 mm long, 3: 6 mm wide, the middle of the spot is grayish brown, the edge is brown, the spot is easy to produce black spots, that is, the apothecium, when serious, several major disease spots fuse, resulting in local dry leaves.

[agricultural control] ① selected high-foot white, three leaves Qi, chicken leg onions, Zhangqiu scallions and other heat-resistant varieties. ② strengthen management, timely drainage after rain, prevent onion fields from getting too wet, improve root activity and enhance disease resistance.

[chemical control] at the initial stage of the disease, 1000 times of 50% carbendazim wettable powder or 70% methyl thiophanate wettable powder were sprayed with 50% carbendazim wettable powder or 70% methyl thiophanate wettable powder. Add 75% chlorothalonil wettable powder 1000 times, once every 7 days, 2 times in a row.

Soft rot of green onion

[incidence characteristics] the bacterial soft rot of Welsh onion is on the rise year by year. Generally, the stem base extends from the bottom to the top, and the initial infection shows water-like long spots, and then produces translucent gray-white disease spots, then the base of the leaf sheath softens and decays, causing the leaves to collapse, the disease spots expand downward, and the pseudostem begins to rot at the beginning of the disease. after that, the interior began to rot, emitting the stench peculiar to bacterial diseases.

[agricultural control] ① increased the application of organic fertilizer to cultivate strong seedlings. Suitable period for planting, ploughing frequently, shallow watering, increasing the application of phosphorus and potassium fertilizer to prevent excessive nitrogen fertilizer. ② can control underground pests and aboveground pests in time and reduce man-made wounds.

[chemical prevention and cure] at the initial stage of the disease, 77% Ke'e wettable powder, 72% streptomycin sulfate soluble powder 2000 times, 10 million units of phytomycin 3000 times or 14% copper complex amine solution 250 times were selected at the initial stage of the disease, once every 7 to 10 days according to the disease. 2 times.

Green onion yellow dwarf disease

[incidence characteristics] Welsh onion yellow dwarf disease, also known as Welsh onion virus disease, can get this disease from seedling stage to adult plant, the growth of diseased plants is blocked, the growth of diseased leaves is stagnant, the leaves are convex and uneven, wrinkled and twisted, the leaves become thinner, and the leaf tips are gradually yellowed. Sometimes yellowish-white stripes or yellow-green mottles of different lengths are produced on the leaves. The seriously diseased plants were seriously dwarfed, the leaves became smaller and flattened, the growth stopped, the wax decreased, the leaves sagged and yellowed, and in severe cases, the whole plant shrunk and died.

[agricultural control] before planting onions in ①, remove weeds in the field, remove diseased seedlings, fertilize and water timely and pay attention not to be adjacent to other onion crops. ② timely control aphids and thrips, choose 10% thalidomide 800 times, or 40% omethoate 1000 times or 50% methamidophos 1000 times mixture. ③ increased application of organic fertilizer, timely topdressing and spraying plant growth regulators to enhance disease resistance.

[chemical control] at the initial stage of the disease, 1.5% Zhiyanling emulsion was sprayed 800 times, or 20% virus A wettable powder 500 times, or 300 times emulsion plus 95,500 times Lufeng, once every 5-7 days, 2 times for 3 times.

Green onion anthracnose

[characteristics of the disease] damage leaves, flower stems and pseudostems. The initial infection of the leaves was nearly spindle-shaped, fusiform to irregular spots, grayish brown to brown, and there were many black spots on the spots, that is, the conidia disk, which caused the death of the upper leaves in severe cases. The pathogen is a fungus of the genus Trichoderma, which overwinters on the infected pseudostem in the soil with the conidium or conidium or mycelium, and is transmitted by Rain Water spatter.

[prevention and treatment methods] in rainy years, the disease is more serious in the low-lying land with poor drainage, which is usually sprayed at the initial stage of the disease with 80% anthrax Fumi wettable powder, or 1000 times of methyl topiramate or 70% Dasheng.

Onion nematode disease

[disease characteristics] the larvae are parasitic on the root of Welsh onion, which causes root rot and makes the whole plant yellow and rotten when seriously damaged. Onion nematode disease is caused by onion stem nematode, eating underground pseudostem and rhizome, sweet potato stem nematode, causing swelling, rupture or decay, root rot nematode harms rhizome or pseudostem, showing root rot or plant non-fibrous root symptoms.

[control methods] the harm can be effectively controlled by treating soil with 30% milol, using 3-4 kg per mu, or spraying and irrigating roots with 50% phoxim 500 times solution.

Retting root

[disease characteristics] retting root is one of the common diseases in vegetable seedlings, and it also often occurs in the adult stage of Welsh onion.

[control measures] ① stabilized the ground temperature, promoted the development of strong seedlings, improved the ability of disease resistance, and increased the temperature of seedling field by more than 20 ℃. ② reduces the humidity in the field, and the high humidity in the field is the key factor for root retting. After watering the soil moisture in the seedling field, irrigate little or no water as much as possible, and frequently irrigate the small water when necessary, and avoid flooding. In cloudy and rainy days or when the humidity in the field is too high, plant ash or fine dry soil can be scattered on the seedling field to reduce the humidity in the field. ③ should improve soil aeration conditions, planting Welsh onions on sandy soil as far as possible, and apply a large amount of rotten organic fertilizer to improve soil structure, improve soil buffering capacity, improve ventilation and air permeability conditions, so as to reduce the occurrence of retting roots.

Liriomyza sinensis

[hazard characteristics] Liriomyza huidobrensis is the main pest that harms the leaves of Allium vulgaris. The larvae enter the leaves and eat the mesophyll tissue in the second layer of epidermis, showing a curved or hemp-shaped tunnel, destroying the green tissue of the leaves and seriously affecting the growth of green onions.

[agricultural control] remove the remains of diseased leaves. During the onion growing period, it is found that the leaves eaten by larvae should be taken out of the field and buried deeply. After harvest, the residual plants should be cleaned up, retted or burned, which can reduce the source of insects, turn deep into the soil, and freeze to death of overwintering pupae in winter.

[chemical control] during the outbreak of adults, 4000-fold solution was sprayed, or 80% dichlorvos 2000-fold solution. During the larval damage period, 25% quinathion EC can be sprayed 1000 times, or 20% trimethophos EC 1500 times, 18% Shachongshuang 600times, 7.5% rotene cyanide EC 1200 times, 10% nicotine EC 800times, all of which can play a better control effect. When the occurrence is large, the medicine is usually used once every 7 days. However, stop using green onions 15 days before harvest to prevent pesticide residues from exceeding the allowable standard.

Thrips

[hazard characteristics] thrips belong to Thysanoptera thrips. Harm to green onions and other vegetables such as onions and garlic. The worm is very small, and the adult is good at jumping. Both nymphs and adults prick and suck the sap of onion leaves, and in severe cases, the injured surface forms small gray-white spots, which shortens the life span of onion leaves and reduces the photosynthetic capacity. Thrips have 6-10 generations a year, which is harmful from May to September, and the damage is serious in summer high temperature and dry weather.

[control method] during the occurrence period, 40% dimethoate EC 600 times was sprayed once every 5-7 days, and continuously sprayed 2-3 times, the control effect was remarkable. The application of old Kang stove soil on the ground can also drive insects and have the effect of topdressing.

Onion fly

[hazard characteristics] onion flies, also known as leek maggots, larvae harm onion and garlic vegetables. In spring and autumn, the pseudostem lays eggs near the ground, and the hatched larvae sneak into the base of the leaf sheath and feed on young leaves and growing points.

[control method] spraying 40% dimethoate EC or 20% germicidal ester EC 2000 times to kill adults during oviposition. When planting, remove the damaged onion seedlings, soak the lower part of the pseudostem with the above pesticides to kill the young maggots that may be lurking inside.