Why Do The Leaves On My Onions Look Unhealthy?

Are the leaves on your onions yellow and the plants look stunted?

Are your onions growing slowly and the plants are pale?

Are there any small insects on your onions?

Is the entire plant yellow and wilted?

Do the onions have soft necks and bulbs that are soft and brown?

Are there any maggots or larvae on the roots and burrowed inside the bulbs?

Do the leaves have white streaks or blotches on them?

Are there any tiny insects on or around your plant?

Do the leaves have water-soaked or papery, white spots with vertical splits on them?

Do the leaves have pale green-brown spots on them?

Is there any fuzzy mold on the leaves?

Do the leaves have sunken, light-colored spots with concentrically ringed, purple centers?

Do the leaves have small reddish to orange blisters on them?

Pale and slow-growing plants are symptoms that usually indicate nitrogen deficiency or waterlogged soil. Spray plants and drench roots with fish emulsion or fish-meal tea to alleviate symptoms. Plant in raised beds to improve drainage and add compost before planting to prevent problems.

Those insects are aphids. These tiny insects can vary in color, green, pink, black, gray and white. Check for aphids on young leaves. You can control them by washing them off the plant with water spray. Introducing ladybugs will keep their number low. Insecticidal soap or neem oil should be used with severe infestations.

If roots and bulbs are pinkish, the plant has Pink root disease. Roots infected with this fungal disease shrivel and die. Destroy infected plants. Prevent problems by ensuring good drainage and adding ample organic matter to the soil. ’Crystal Wax Pickling’, ‘Early White Supreme', ‘Hybrid Big Mac’ and ‘JK Special’ are resistant cultivars.

Your plant is infected with the fungal disease Fusarium bulb rot. Destroy infected plants. Prevent problems by planting cultivars like 'Long White Summer Bunching', ‘Northern Oak', ‘Sentinel' and ‘Valiant’ that are somewhat resistant.

Onion maggots and Lesser bulb fly larvae feed on roots, killing seedlings and older plants. Onion maggots are white and taper to a point at the head. Lesser bulb fly larvae are wrinkled and yellow-gray. Destroy infested plants. Do not compost them. Apply parasitic nematodes to the soil before planting and cover plants with row cover.

Yellow or reddish-brown, slender, tough-bodied, segmented worms feeding on roots and bulbs are wireworms. Adults are dark-colored, elongated click beetles. Apply parasitic nematodes to the soil before planting to control them.

Onion thrips cause blotches on onion leaves, tips may be distorted or brown. Adults are tiny, slender, yellow-brown, rapidly moving, winged insects. The larvae can barely be seen with the naked eye. Treat plants with insecticidal soap or a commercial pyrethrin spray or dust to control thrip infestations.

Excessive rain or hail can spot onion leaves. Spots are various sizes, and damage doesn't spread. Maintain good air circulation and make sure soil is well-drained to minimize problems.

Onion leaf blight is a fungal disease that causes these symptoms. Leaf tips turn yellow and brown. Spray plants with sulfur as soon as you see symptoms if the weather is cool and humid. 'Tokyo Long White' is a tolerant cultivar.

Downy mildew is a fungal disease that is known to infect onions. Spray plants with sulfur to prevent the disease from spreading in cool, wet weather. Don't handle plants when wet to avoid spreading the disease.

Irregular areas with tiny brown flecks are caused by high levels of ozone in the air. Spray plants with seaweed extract and fish emulsion to encourage new growth.

The fungal disease Purple blotch causes these symptoms. Spots enlarge and girdle leaves, which wither and fall over. Spray plants with sulfur if the disease is present to keep it from spreading. Cool soil makes plants more prone to this purple blotch.

Leaves infected with fungal disease Rust may turn yellow and die. Bulbs are small. Clean up and dispose of tops to eliminate overwintering spores.

If the leaves have black streaks filled with dark brown powder the cause is the fungal disease Smut. Young plants are usually affected. Cool soil makes plants more prone to this fungal disease. Warm soil by covering it with clear plastic for a few weeks before you plant.