Garlic is a major vegetable crop in China, and many people grow it at home. During the garlic growing process, the problem of yellowing leaves is a common issue. So, what disease causes yellowing leaves in garlic? What medicine should be used? Let's find out below.
1. Leaf blight
It mainly affects the leaves, and infection usually occurs from the leaf tip or other parts of the leaf. In the early stage, it appears as small white round spots, which expand into irregular or oval shapes, and then turn into grayish-white or grayish-brown lesions.
Control measures: Apply pesticides promptly at the initial stage of disease in the field. Commonly used agents include: 80% mancozeb wettable powder at 600 times dilution, or 75% chlorothalonil wettable powder at 500 times dilution, or 25% pyraclostrobin suspension at 1000 times dilution, or 10% difenoconazole water-dispersible granules at 1500 times dilution, or 64% cymoxanil-mancozeb wettable powder at 600 times dilution, or 50% iprodione wettable powder at 1000 times dilution, etc. Apply once every 7-10 days, alternating between pesticides for 3-4 consecutive treatments.
2. Leaf blight
It mainly affects the leaves. In the early stages of infection, the disease appears as pale white or light yellow water-soaked spots on the middle or tip of the leaf with light green edges. The spots spread rapidly.
Control measures: Preventative spraying can be used before disease outbreaks. Recommended formulations include 65% zineb at 800-1000 times dilution, 20% benzoyl + pyraclostrobin at 1500 times dilution, or thiophanate-methyl + potassium dihydrogen phosphate. It is recommended to spray once in winter or early spring for good preventative effect. Later, after disease outbreaks, spray with 66.8% propineb + isopyram wettable powder at 600-800 times dilution, 52.5% cymoxanil + cymoxanil at 1500 times dilution, 60% mancozeb + flumorph at 1000 times dilution, or 68% metalaxyl-mancozeb at 2000 times dilution, etc. Combined with nutrient-rich agents, spraying twice a week at the same time yields the best results.
3. Bacterial soft rot
When garlic is infected, the disease first appears on the leaf margin or midrib, with yellowish-white streaks appearing along the leaf margin or midrib, which can run through the entire leaf. When the humidity is high, the diseased parts turn into yellowish-brown soft rot.
Prevention and treatment: In the early stage of the disease, spray with 500 times dilution of 77% copper oxychloride wettable powder, or 500 times dilution of 50% copper oxychloride wettable powder, 500 times dilution of 12% copper oxychloride emulsifiable concentrate, 300 times dilution of 14% copper oxychloride aqueous solution, or 4000 times dilution of 72% agricultural streptomycin sulfate soluble powder. Spray once every 7-10 days, and continue for 2-3 times depending on the severity of the disease.
