Control of Common Diseases and Pests in Garlic [Part II]

Following the first part on the prevention and control of common diseases and pests affecting garlic, let’s now take a look at… of garlic Other common pest and disease control:

5. Flowering Leaf Disease

Symptoms: In the early stages of the disease, discontinuous yellow streaks appear along the leaf veins, which later coalesce into long, alternating yellow‑green stripes. Plants become stunted, and in some cases the heart leaves are enclosed by adjacent blades, resulting in a curled, deformed appearance that fails to fully expand over time, leading to twisted foliage. The bulbs of infected plants shrink, and the number of cloves and fibrous roots decreases; in severe cases, the cloves become rigid. These changes are particularly pronounced during storage, causing a marked decline in both yield and quality and ultimately leading to genetic degeneration.

Control methods: Conduct rigorous seed selection and, whenever possible, establish a foundation‑seed base; use bulbs from low‑incidence areas as planting material to reduce the incidence of virus carriage. In vitro culture of meristematic tissue from garlic scapes can be employed to eliminate viruses from bulbils, producing virus‑free seed garlic. Avoid intercropping or continuous cropping with onions, chives, and other susceptible crops to minimize natural transmission in the field. Apply insecticides to garlic fields and surrounding crops to control aphids and prevent recurrent viral infections. Strengthen fertilizer and irrigation management to delay premature senescence and enhance plant resistance. At the onset of symptoms, spray with a 1,000‑fold dilution of 1.5% Zhībìnglíng emulsifiable concentrate, a 500‑fold dilution of 20% Virus A wettable powder, or a 250–300‑fold dilution of Antivirus Agent No. 1 aqueous formulation, repeating every 10 days for 2–3 consecutive applications.

6. Bacterial Soft Rot Disease

Symptoms: When garlic is infected, the disease initially appears at the leaf margins or along the midrib, forming yellowish‑white streaks that may extend across the entire leaf. Under high humidity, the affected areas turn yellowish‑brown and become soft and rotting. Typically, the lower leaves are the first to show symptoms, which then progress upward, eventually causing the entire plant to turn yellow and wither or die.

Control methods: In the early stages of the disease, promptly spray with a 500‑fold dilution of 77% Kasugamycin wettable powder, or a 500‑fold dilution of 50% copper‑sodium octanoate wettable powder, a 500‑fold dilution of 12% copper‑based emulsifiable concentrate, or a 300‑fold dilution of 14% copper‑ammonium complex aqueous solution. Alternatively, use a 4,000‑fold dilution of 72% streptomycin sulfate soluble powder. Repeat applications every 7–10 days, and continue treatment 2–3 times depending on the severity of the disease.

7. Yellow leaves and dry tips

Symptoms: During the seedling stage, garlic exhibits yellowing of the leaves; in mature plants, tip drying occurs.

Prevention and control Methods: Apply well‑decomposed organic fertilizer. Rotate crops in garlic fields. Pay close attention to timely control of onion maggots. To prevent bulb rot and yellowing tips, begin topdressing and irrigation before the onset of bulb rot, thereby reducing the occurrence of yellow leaves and dry tips and promoting the differentiation of flower stalks and garlic cloves.

8. Garlic Maggot

Organic fertilizers must be fully composted. During the garlic maggot‑infestation period (early April), apply a 1,000‑fold dilution of 50% phoxim emulsifiable concentrate or an 80% trichlorfon crystal solution at 500 times dilution by drenching the roots; alternatively, spray with a 1,000‑fold dilution of dichlorvos to repel adults and kill eggs, and apply a 300–500‑fold dilution of 48% chlorpyrifos emulsifiable concentrate to the soil surface.

9. Onion thrips

After the onset of spring, promptly apply a 20% imidacloprid emulsifiable concentrate diluted 5,000–7,000 times or a 50% dichlorvos solution diluted 800 times to reduce pest populations and mitigate damage.

The above is an overview of common disease and pest management techniques for garlic. Garlic growers can refer to these methods and, in light of their specific growing conditions, implement appropriate control measures.