Why Do My Petunias Look Sickly?

Do the leaves and flowers have died, gray blotches?

Are the leaves covered with white powder?

Are the older leaves turning yellow and wilting, an overall decline in plant vigor is apparent?

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

Are the leaves stippled, reddish or yellowish with fine webbing?

Do the leaves and buds have feeding damage?

Are the stems, crowns, and/or roots rotted, leaves are wilting?

Dead blotches on leaves and flowers are symptoms that indicate a fungal disease - Botrytis blight. You can prevent Botrytis blight disease by planting flowers in areas with good air circulation. Water plants sparsely. Heavily infected plants should be removed. Spray weekly with a copper fungicide until the disease is under control.

White, powdery patches on the leaves are caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining them and any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further infections.

These symptoms indicate fungal disease Verticillium wilt. Verticillium infects a wide range of plant species. Destroy all infected plants, as there is no cure. Prevent problems by presoaking seed in a 10 percent bleach solution.

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.

Reddish to yellowish flecks on leaves and webbed foliage indicate spider mites. These tiny, spider-like pests feed by sucking sap from the underside of the plants leaves causing yellow flecking on the upper leaf surfaces. You can control spider mites by spraying plants thoroughly with water 2-3 times a day for several days. For severe infestations, spray plants with insecticidal soap, or pyrethrin as a last resort.

Caterpillars chew through foliage and buds of petunias, sometimes causing extensive damage. Remove these pests by hand and destroy them. For heavier infestations spray BTK (Bacillus thuringiensis) weekly for 3-4 weeks.

Petunias are susceptible to several Stem, Crown, or Root rot diseases. Crown injury and excess moisture increase the chances of infection. Choose well-drained sites. Add organic matter to improve soil drainage. Remove and discard infected plants and the surrounding soil.

Several viruses affect petunias, causing leaves to develop yellow spots, mosaics, halos, or bullseyes. Viruses cannot be cured, so the infected plants should be removed and destroyed. Many plant viruses are vectored by small insects like thrips, so the best form of control is dealing with these pests.