Garlic - Pests and it’s Control

Bulb mites: Stunted plant growth; reduced stand; bulbs rotting in ground or in storage; pest is a cream-white, bulbous mite <1 mm in length, which resembles a pearl with legs.

Damage to plants by bulb mites allows secondary invasion by other pathogens and can cause bulb rots.

Management: Do not plant successive crops of onion or garlic in same location; allow field to fallow to ensure that any residual organic matter decomposes completely - crop residues can harbor mite populations; treating garlic seed cloves with hot water prior to planting may help reduce mite populations.

Leafminers : Thin, white, winding trails on leaves; heavy mining can result in white blotches on leaves and leaves dropping from the plant prematurely; early infestation can cause yield to be reduced; adult leafminer is a small black and yellow fly which lays its eggs in the leaf; larvae hatch and feed on leaf interior.

Mature larvae drop from leaves into soil to pupate; entire lifecycle can take as little as 2 weeks in warm weather; insect may go through 7 to 10 generations per year.

Management :Check transplants for signs of leafminer damage prior to planting; remove plants from soil immediately after harvest; only use insecticides when leafminer damage has been identified as unnecessary spraying will also reduce populations of their natural enemies.

Onion maggot : Stunted or wilting seedlings; plant will commonly break at soil line if an attempt is made to pull it up; if infestation occurs when plants are bulbing, bulbs will be deformed and susceptable to storage rots after harvest; adult insect is a greyish fly which lays white, elongate eggs around the base of the plant; the larvae that emerge from the eggs are tiny and white and bore into the plant; mature larvae are about 1 cm (0.4 in) long with feeding hooks.

Comments : Females can lay several hundred eggs during their 2-4 week lifespan; insect overwinters as pupae in the soil.

Management : Management of onion maggots is heavily reliant on good snaitation; all onion bulbs should be removed at the end of the season as maggots will die without a food source; commercial onion growers must often rely on the application of appropriate granular insecticides and, in some cases, insecticide sprays are also required; home gardeners should try to remove any volunteer wild onion and chive plants as these can act as an infection source; floating row covers may help to protect plants and prevent females from laying eggs around plants.

Thrips (Onion thrips, Western flower thrips) Discolored, distorted tissue; scarring of leaves; severly infected plants may have a silvery appearance; insect is small (1.5 mm) and slender and best viewed using a hand lens; adult thrips are pale yellow to light brown and the nymphs are smaller and lighter in color

Comments : Onion thrips and western flower thrips have an extensive host range and can be introduced to garlic from other plants.

Management : Natural enemies include some species of predatory mite, pirate bugs and lacewings; avoid planting onion in close proximity to grain fields as thrips populations build up on these plant in the spring; overhead irrigation of plants may help reduce thrips numbers; apply appropriate insecticides at first sign of thrips damage.

Lesion nematode: Stunted plants; root system lacks fine roots; round or irregular lesions on roots.

Comments: Lesion nematode has one of the widest host ranges of any nematode; nematode enters the plant through the root epidermis and consumes cell contents.

Management: Hot water dips can be used to control nematodes in bulbs; crop rotation is not usually very effective at controlling lesion nematodes due to its extensive host range.

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