Detailed Explanation of Key Points for Garlic Mite Pest Control Techniques

Through observation and research, three species of mite pests damaging garlic and their basic morphological characteristics, biological traits, and damage symptoms were preliminarily identified, and effective control methods were proposed.

(1) Root mite: widely distributed, fast reproducing, and severely damaging; it is a dangerous pest of garlic both in the field and during storage. Adult mites are 0.58-0.81 mm long, broadly oval, pear-like in shape, white on the surface, smooth and shiny, with 4 pairs of short and thick legs. Eggs are oval, 0.2 mm long, milky white, and relatively transparent. They overwinter as adult mites and nymphs in garlic plants or in the soil, and can also overwinter as eggs inside garlic bulbs. Adult mites lay eggs in the depressions at the base of garlic bulbs, mostly singly or in small numbers, with each female mite laying about 600 eggs. They generally reproduce 1 generation every 20-30 days. The suitable development temperature is 20-25°C. They are prone to occurring in acidic sandy soil rich in organic matter. Adult mites and nymphs bore into and feed on the bulbs of garlic plants, causing the damaged bulbs to rot and smell foul, and the aboveground parts to wither and die. When stored garlic heads are damaged, they also rot and smell foul or dry out into empty shells.

(2) Mold mite: a worldwide pest, widely distributed, fast reproducing, and severely damaging. It mainly damages stored garlic heads, and in recent years has also occurred in garlic fields. Adult mites are oval, 0.51-0.61 mm long and 0.27-0.29 mm wide. The body surface is smooth, milky white, semi-transparent, with 4 pairs of short and thick legs. Eggs are elongated oval, 0.09-0.12 mm long and 0.05-0.08 mm wide, milky white. They overwinter as eggs, nymphs, or adult mites inside garlic heads. Adult mites lay eggs in the gaps at the base of garlic cloves on the stem plate of garlic bulbs, or in holes in damaged areas, mostly in piles and occasionally singly. Each female mite lays 85-100 eggs. The suitable reproduction temperature is 20-24°C, and the most suitable relative air humidity is 80%-90%. Mold mites are gregarious and prefer living in damp, moldy environments. When adult mites and nymphs damage garlic heads, they initially bore into and feed on the surface of garlic cloves, then gradually bore into the interior of the cloves, forming many irregular holes. Damaged garlic heads rot under moist conditions, while under dry conditions they turn yellow and shrivel. In the field, after the base of the plant bulb is damaged, it causes rotting and a foul odor, leading to plant death.

(3) Gall mite: also called tulip mite, widely distributed and a worldwide pest. In addition to damaging allium vegetables, it also damages wheat, corn, and trees. Adult mites are very small, carrot-shaped, milky yellow vermiform mites. Female mites lay eggs on the surface of garlic cloves, mostly singly, with very few laid in piles. Eggs are nearly spherical, milky white, and slightly transparent. Newly hatched nymphs are colorless and semi-transparent, gradually turning milky white after molting, with body color slightly deepening as mite age increases. The optimal temperature for reproduction is 15-20°C, and the optimal relative air humidity is 70%-95%. When the temperature is below 3°C and the relative air humidity is below 60%, reproduction stops. Adult mites and nymphs damage stored garlic heads, and sometimes field garlic heads can also be damaged. They mostly invade from the edge gaps of the stem plate of garlic heads, piercing and sucking sap from the fleshy part at the base of garlic cloves, then gradually move to the tips of the cloves to cause damage, causing the cloves to gradually wilt, turn brown, and dry up, with the garlic head becoming an empty shell. Under high humidity conditions, wounds on damaged garlic heads can also be infected by many pathogens, causing the garlic heads to rot and smell foul. Gall mites are also vectors of viral diseases, with a large virus-carrying capacity, fast virus transmission, long infectious period, and severe damage; their virus transmission rate to garlic reaches 100%. Garlic that has been damaged by gall mites will produce seedlings after sowing that show various viral disease symptoms, grow slowly, do not bolt, and do not form garlic heads, or form single-clove garlic.

Control methods for mite pests: Because garlic mite pests can occur during garlic head storage and also during field growth, control work can be carried out from the following aspects:

First, if mite damage is found during garlic head storage, sulfur powder fumigation can be used. Use 100 grams of sulfur powder per 1 cubic meter of space, add a small amount of sawdust, mix well, place in a container, and put it in the garlic head storage room. After igniting, close doors and windows and fumigate for 24 hours. The mite-killing effect reaches 100%, but it is ineffective against eggs, so fumigate once more after the eggs hatch.

Second, do not practice continuous cropping with Welsh onion, onion, or Chinese chives, and do not plant them adjacent to each other; implement a 3-4 year crop rotation.

Third, strictly select seed before sowing, discard garlic cloves with disease or pests, then soak the selected seed cloves in a 1000-fold dilution of 80% dichlorvos emulsifiable concentrate for 24 hours. The mite-killing effect can reach 100%. The garlic skin, garlic roots, residual garlic scape stubs, and stem plates left after breaking apart the garlic must all be collected and burned to reduce infection sources.

Fourth, before sowing, evenly broadcast disulfoton granules into the sowing furrow, 3-4 kg per 667 sq m. Fifth, during field growth of garlic, irrigate the roots with a 300-400 fold dilution of 80% dichlorvos emulsifiable concentrate.

Sixth, promptly remove damaged plants in the field and burn or deeply bury them to reduce mite sources.