What is wrong with my lovage?

Do the leaves have yellow-brown, concentrically ringed spots?

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

Are there any yellow-green circular patches between leaf veins that later turn into distinct lesions with irregular margins?

Do the leaves have wandering, white or translucent tunnels in them?

Are the leaves curled and yellow?

Are the flowers deformed or dwarfed?

Are there any green worms with a brilliant, yellow-dotted black band across each body segment?

Yellow-brown and concentrically ringed spots are caused by fungal disease - Alternaria blight. This disease attacks lower leaves first. As the disease progresses leaves and eventually the whole plant will die. Spray plants with copper at the first signs of disease.

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.

Ramularia leaf spot is caused by a fungus that overwinters on plant debris. Remove weeds and any plant debris from around plants. Avoid the use of sprinklers for irrigation. Remove and destroy any infected plants to prevent spread. If the disease is problematic it may be necessary to treat them with copper fungicides.

These symptoms indicate leafminers. These tiny white, maggotlike larvae feed inside leaves. Prune off and destroy all infested leaves. Cover plants with row cover until flowers open to prevent adults from laying eggs on plants. Certain nematodes can attack leafminer larvae inside leaf tunnels.

Distorted, curled leaves are caused by aphids. These tiny insects cluster under leaves and on growing tips where they feed on plant sap. You can control them by washing them off the plant with water spray. Insecticidal soap should be used with severe infestations.

Tarnished plant bugs inject a plant-deforming toxin as they feed on young leaves. Trap them with white sticky traps or treat plants with a commercial pyrethrin spray or dust in the evening to control severe infestations. The best way to prevent this pest is through a thorough fall and spring cleanup. This will prevent it from overwintering.

Parsley worms are known to feed on lovage plants. This voracious feeder is the larvae of the black swallowtail butterfly. You can remove them by handpicking or applying an environmentally-friendly Bt (Bacillus thuringiensis) product. The adult butterflies are pollinators so if you don't have too much trouble with them you should just let them be. The worms generally prefer parsley over other plants, so plant it as a companion trap crop.

Leaves that are covered in coarse stippling and may appear silvery indicate thrips. 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.