How to prevent and control pests and diseases in Welsh onions? Latest technical method tutorial
The Welsh onion is a perennial herbaceous plant with cylindrical, hollow leaves that are fragile and easily broken, and are green in color. In East Asian countries and Chinese communities everywhere, scallions are often eaten as a very common spice, seasoning, or vegetable, and play an important role in Eastern cooking. Below, the editor will introduce the pest and disease prevention and control techniques for Welsh onions!
Welsh onion brown leaf spot
[Disease characteristics] Welsh onion brown leaf spot, also known as leaf tip yellow wilt disease, mainly damages the leaves. Infected leaves tend to start from the upper part, initially showing water-soaked yellowish-brown spots, then forming spindle-shaped lesions, generally 10-30 mm long and 3-6 mm wide. The center of the lesion is grayish-brown, the edge is brown, and small black dots, namely ascocarps, are easily produced on the surface of the lesion. In severe cases, several large lesions merge, causing local drying and death of the leaves.
[Agricultural control] 1. Choose heat-tolerant varieties such as Gaojiao Bai, Sanye Qi, Jitui Cong, and Zhangqiu Welsh onion. 2. Strengthen management, drain water promptly after rain, prevent the onion field from becoming too wet, improve root vigor, and enhance disease resistance.
[Chemical control] At the early stage of disease, spray 50% iprodione wettable powder or procymidone wettable powder at 1000 times dilution, or use 50% carbendazim wettable powder at 800 times dilution or 70% thiophanate-methyl wettable powder at 1000 times dilution, plus 75% chlorothalonil wettable powder at 800 times dilution, once every 7-10 days, spraying 2-3 times in succession.
Welsh onion soft rot
[Disease characteristics] Bacterial soft rot of Welsh onion has shown an upward trend year by year. It generally spreads first from the stem base upward. The initial infection appears as water-soaked elongated spots, then produces semi-transparent grayish-white lesions. Next, the base of the leaf sheath softens and rots, causing the leaves to fall over. The lesions expand downward. When the pseudostem is infected, it initially appears water-soaked, then the interior begins to rot, giving off the foul odor peculiar to bacterial diseases.
[Agricultural control] 1. Apply more organic fertilizer and cultivate strong seedlings. Plant at the appropriate time, cultivate frequently, water lightly, apply more phosphorus and potassium fertilizer, and prevent excessive nitrogen fertilizer. 2. Timely control underground pests and aboveground pests to reduce artificial wounds.
[Chemical control] At the early stage of disease, choose 77% copper hydroxide wettable powder at 500 times dilution, 72% streptomycin sulfate soluble powder at 2000 times dilution, 10 million units of new phytomycin at 3000 times dilution, or 14% copper complex water agent at 250 times dilution. Depending on the condition, apply once every 7-10 days, for 2-3 consecutive treatments.
Welsh onion yellow dwarf disease
[Disease characteristics] Welsh onion yellow dwarf disease, also known as Welsh onion viral disease, can affect Welsh onions from the seedling stage to the mature plant stage. The growth of diseased plants is inhibited, the growth of diseased leaves stagnates, the leaves become uneven, shrunken and distorted, the leaves become thinner, and the leaf tips gradually turn yellow. Yellow-white stripe spots of varying lengths or yellow-green mottling sometimes appear on the leaves. Severely diseased plants are severely dwarfed, with twisted, smaller, flattened leaves, growth stops, waxiness decreases, and leaves droop and turn yellow. In severe cases, the whole plant shrivels and dies.
[Agricultural control] 1. Before planting Welsh onions, remove field weeds, remove diseased seedlings, apply additional fertilizer and water at the right time, and take care not to plant adjacent to other onion crops. 2. Timely control aphids and thrips. Choose 10% mevinphos at 800 times dilution, or 40% omethoate at 1000 times dilution, or a mixed solution of 50% methamidophos at 1000 times dilution for spraying. 3. Apply more organic fertilizer, topdress at the right time, spray plant growth regulators, and enhance disease resistance.
[Chemical control] At the early stage of disease, spray 1.5% plant virus inhibitor emulsion at 800 times dilution, or 20% virus A wettable powder at 500 times dilution, or use Xiaoyedi emulsion at 300 times dilution plus Lufeng Jiuwu at 500 times dilution for spraying, once every 5-7 days, for 2-3 treatments.
Welsh onion anthracnose
[Disease characteristics] It damages leaves, flower stalks, and pseudostems. Initial infection on leaves appears as nearly spindle-shaped, fusiform to irregular spots, light grayish-brown to brown, with many small black dots on the spots, namely the pathogen's acervuli. In severe cases, it causes the upper leaves to wither and die. The pathogen belongs to the fungus Colletotrichum circinans in the genus Colletotrichum, subphylum Deuteromycotina. It overwinters as stromata, acervuli, or mycelium with diseased residues in the soil or on infected pseudostems, and spreads by rain splash.
[Control methods] In rainy years with long periods of continuous overcast and rainy weather, disease is more severe in low-lying areas with poor drainage. Generally, use 80% thiram wettable powder at 800 times dilution, or 70% thiophanate-methyl at 1000 times dilution, or 70% Daconil at 600 times dilution for spraying at the early stage of disease.