Detailed Guide to Identifying and Controlling Common Pests and Diseases of Onions and Garlic
Allium vegetables are a group of vegetables with a distinctive odor. They are rich in sugars, vitamin C, and minerals such as sulfur, phosphorus, and iron, and contain antibacterial substances (propylene sulfide), which help stimulate appetite, add flavor, remove fishy odors, and provide medicinal benefits.So what pests and diseases affect onions and garlic? How to control them? What techniques are there?
What pests and diseases affect onions and garlic?
At present, the main pests and diseases occurring on onions and garlic include leaf blight, purple blotch, white rot, downy mildew, thrips, aphids, and lepidopteran pests. To ensure high quality, high yield, and high efficiency of garlic and scallions, control efforts should adhere to the plant protection policy of “prevention first, integrated control,” implement the new concepts of “public plant protection and green plant protection,” take agricultural control as the foundation, carry out health-promoting cultivation, demonstrate and promote green control techniques, and conduct chemical control scientifically according to the occurrence patterns of onion and garlic pests and diseases.
How to control onion and garlic pests and diseases? What techniques are there?
1. Agricultural control
Adopt agricultural technical measures such as cleaning the fields, scientific fertilization and irrigation, and strengthened cultivation and management to create ecological and environmental conditions favorable for the growth of garlic and scallions but unfavorable for the occurrence and damage of pests and diseases, enhance plant resistance, and reduce pest and disease damage.
2. “Three lures” control techniques
(1) Insect-killing lamp trapping. Use insect-killing lamps to trap and kill adult lepidopteran pests, installing one lamp every 30-50 mu.
(2) Color board trapping. Use yellow sticky boards and blue sticky boards to trap and kill thrips and aphids, hanging 20-30 sticky insect boards (20 cm × 24 cm) per mu.
(3) Sex pheromone trapping. Use sex pheromones to trap and kill lepidopteran pests such as the tobacco cutworm and beet armyworm, setting up 2 sets of sex pheromones per mu.
3. Chemical control
Use pesticides scientifically and rationally, apply the right pesticide for the right problem, alternate pesticides, strictly observe pesticide pre-harvest intervals, and prohibit the use of highly toxic and high-residue pesticides; adopt new spraying equipment to improve the atomization effect of the spray solution, thereby reducing pesticide dosage, improving pesticide effectiveness, and enhancing control results.
(1) Garlic and scallion leaf blight and purple blotch. In the early growth stage of garlic and scallions, that is, before the seedling stage and flower bud and bulb differentiation stage for garlic, and before the tillering stage for scallions, spray 70% mancozeb WP at 500-600 times dilution or 75% chlorothalonil WP at 500-600 times dilution and other pesticides for preventive spraying, once every 10 days, for 2-3 consecutive treatments; in the early stage of disease occurrence, choose 10% difenoconazole WG at 4000-5000 times dilution or 75% chlorothalonil WP at 500-600 times dilution or 25% propiconazole EC at 2500-3000 times dilution for spray control, once every 7-10 days, for 3-4 consecutive treatments.
(2) Garlic white rot. In the early stage of disease occurrence, spray the leaves and drench the roots and stems with 70% thiophanate-methyl WP at 500-600 times dilution or 50% iprodione WP at 1000-1500 times dilution and other pesticides, once every 7-10 days, for 2-3 consecutive treatments.
(3) Scallion downy mildew control. In the early stage of disease occurrence, choose 77% copper hydroxide WP at 1000-1500 times dilution or 50% dimethomorph water-dispersible granules at 1000-1500 times dilution or 50% metalaxyl-mancozeb wettable powder at 500-600 times dilution or 72.2% propamocarb hydrochloride at 1500-2000 times dilution or 94% cymoxanil technical material at 1500-2000 times dilution for spray control, once every 7-10 days, for 3-4 consecutive treatments.
(4) Thrips and aphids. Choose 70% imidacloprid water-dispersible granules at 3000-4000 times dilution or 5% acetamiprid microemulsion at 2000-3000 times dilution or 25% thiamethoxam wettable powder at 4000-5000 times dilution or 50% pymetrozine water-dispersible granules at 4000 times dilution for spray control, once every 7 days, for 2-3 consecutive treatments.
(5) Lepidopteran pests. When larvae are in the 1st-2nd instar stage, choose 50% flufenoxuron emulsifiable concentrate at 1000-1500 times dilution or 10% beta-cypermethrin emulsifiable concentrate at 2000-2500 times dilution or 5% emamectin benzoate water-dispersible granules at 3000-4000 times dilution for spray control, once every 7 days, for 2-3 consecutive treatments.