What Is Wrong With My Scallions?

Are there any dark and withered lesions on seedling stems, lesions may be black and greasy, seedlings are dying?

Do the leaves have pale areas on upper surfaces and "downy" patches underneath?

Are the bulbs small and soft and the roots pinkish or shriveled?

Are the leaves pale on their upper side and are there any dusty blisters on the undersides?

Are there any blister-like lesions near the base of the bulb and streaks on leaves, sheaths, and bulbs?

Are the seedlings clipped off at the soil line?

Do the leaves have large, ragged holes in them?

Are the leaves covered in coarse stippling and may appear silvery?

Are the plants yellow and wilted, the bulb is filled with tunnels?

These symptoms indicate damping-off disease. Remove and destroy all infected plants. To prevent damping-off let the soil surface dry between waterings, thin seedlings to avoid overcrowding, and do not add nitrogen fertilizers until plants have developed leaves. Avoid planting until the soil is sufficiently warm.

Pale areas on upper surfaces of the leaves and "downy" patches underneath are caused by Downy mildew. This fungus spreads quickly during cool, wet nights and warm, humid days. Leaves will wilt and die. Remove and destroy all affected plant parts and encourage good air circulation around plants by thining them. Water plants early in the morning to make sure they dry before nightfall.

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. Plant as early as possible so the bulb of the plant growth will be in cooler temperatures. Rotate crops and plant-resistant varieties.

Likely cause for these symptoms is a fungal disease - Rust. Provide good air circulation around plants by thining them. Avoid making leaves wet when watering. All infected leaves should be removed. Spray leaves with sulfur early in the season to prevent rust or to treat mild infections.

Onion Smut attacks mostly young seedlings as the new leaves emerge. The fungus stunts the growth of the plants. More mature plants are less susceptible. It is most prevalent in temperatures under 75 degrees F. The disease lives in the soil for several years. Rotate crops and do not plant in the same area for at least three years. Encourage rapid growth with watering and fertilizer to get plants past the susceptible stage.

If the seedlings are cut off at the soil level, the most likely cause are cutworms. They feed at night by cutting off young plants and sometimes eating them whole. Control them by introducing parasitic nematodes to the ground. Using BTK spray on the ground will also control their numbers.

Large, ragged holes in the leaves are caused by slugs and snails. Slugs and snails feed on the plant leaves usually at night. To control slugs and snails use diatomaceous earth around your plants. You can also handpick them during the night or use shallow dishes filled with beer as a trap.

These symptoms may indicate thrips. Thrips are tiny, yellow to black flying insects. Severely infected plant parts should be removed and destroyed. Control thrips by introducing lady beetles or lacewings, their natural predators. Insecticidal soap helps in severe infestations.

Onion Maggots attack the bulb rather than the leaves of scallion plants, but this feeding habit can be a severe problem even for scallion growers because the entire seedling eventually dies. Pull all the plants and use what greens you can. Destroy the rest of the plant parts because the flies that produce onion maggots can continue to lay eggs, causing problems for future crops. Apply parasitic nematodes to the soil before planting and cover plants with row cover.

Onion Nematodes are microscopic worms that live in the soil. They inject a toxin into root systems that cause scallion tops to turn yellow with blackened tips. The entire plant can become deformed. Pull up affected plants, chop off any usable tops for kitchen use, and discard the rest of the plant. Crop rotation can reduce the damage to future scallion crops.