After entering the autumn, as the weather is cooler, the growth of green onions enters a critical period of white growth and boldness. It is also a period of high incidence of diseases and insects, and this article puts forward several opinions on the control of diseases and insects.
<h1 class="pgc-h-arrow-right" > disease</h1>
Purple spot disease: also known as black spot disease, rotunda disease. The main manifestation is that it initially appears as a small white dot like a water stain, then becomes a light brown round or spindle-shaped depression, and continues to expand to appear brown or dark purple. The disease is more severe in sandy soils, drylands, and plots with insufficient fertilizer, and in plots where thrips are rampant, mainly harming leaves.
Prevention and control methods. Strengthening fertilizer and water management can increase disease resistance and reduce the incidence of disease. At the beginning of the occurrence, it can be sprayed with 75% Bacillus Qing 170% Tolbuzin (1:1) 1000 to 1500 times liquid, or agricultural resistance 120 water agent 200 times liquid spray. Spray 2 to 3 times in a row, with an interval of 7 to 15 days.
Soft rot: the bulbs that mainly harm the green onion, the initial stage of the disease is water-stained, the harmful parts begin to soften and rot, resulting in yellowing of the leaves of the plant, drying of the leaf tips, the entire plant is not wrinkled, the lax system becomes brown and dies, and finally the whole plant begins to rot and has a foul odor.
Prevention and control methods. Timely removal of stagnant water after rain, timely cultivation and humidification after sunny days, increase soil permeability, reduce disease. Do not touch the plant in field work to avoid wound infection and disease. When the diseased plant is found, it is immediately dug up and burned, and the hole is disinfected with quicklime. At the beginning of the disease, it can be prevented by spray spraying 72% agricultural streptomycin 4000 times liquid or 77% copper hydroxide wettable powder 500 times liquid. Spray the agent twice in a row, with an interval of 7 to 10 days.
Rust: The onset of the disease begins with orange-yellow or black-brown sore spots, followed by orange-yellow powder. Nutrients are insufficient, and the incidence is more severe at low temperatures.
Prevention and control methods. Topdressing phosphorus and potassium fertilizer, timely watering and medium cultivation, and reasonable soil cultivation are effective prevention and control methods. At the beginning of the disease, it can be sprayed with 15% triazolone wettable powder 2000 to 2500 times liquid, once every 10 days, and sprayed twice.
<h1 class= "pgc-h-arrow-right" > insect infestation</h1>
Thrips: Occurs in multiple generations a year, and the autumn is more harmful in September. It mainly harms the heart leaf and young leaves, so that the onion leaves form long yellow and white patches, and the leaves droop or even wither when severe.
Prevention and control methods. Strengthen the management of green onion fertilizer and water to enhance the insect resistance of plants. Setting up a blue plate in the field is also more effective. Chemical control, to choose high efficiency, low residue pesticides, to ensure that green onions environmental protection and safety. Generally, 5% imidacloprid emulsion can be sprayed with 2000 to 3000 times and 3% acetamidine 1500 to 2000 times liquid spraying to achieve fast results.
Onion fly: also known as maggots, the harm often causes the leaves to wither and yellow, shrink and die, farmers often say "ditch". For the prevention and control methods, see my single article "Garlic maggot prevention and control should be early and clever", "Soil method three strokes to eliminate maggots", because maggots in onions, garlic, leeks can harm the prevention and control methods are basically the same, and will not be repeated.