What Is Wrong With My Lindenleaf Rosemallow?

Are there any small translucent spots on leaves, spots later turn black?

Are the leaves and flowers covered with gray mold?

Are the leaves curled and yellow?

Are the leaves distorted, yellowed, and stippled?

Do the leaves and flowers have holes?

Did the leaves become distorted due to excess moisture in the soil?

Bacterial leaf spot causes circular translucent spots scattered over the leaf surface between the veins. These spots turn brownish-black and may spread to form large patches of dead tissue. To prevent the spread of this disease, avoid working around wet plants. Remove and destroy affected parts. Spray Bordeaux mix on remaining plants.

Likely cause for these symptoms is a fungal disease - Botrytis blight. Other symptoms include brown to black spots that may appear on leaves and petals. You can only prevent Botrytis blight disease by planting sweet alyssums in areas with good air circulation. Water plants sparsely. Infected plants should be removed. Spray weekly with a copper fungicide until the disease is under control.

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

Leaves stippled with yellow are caused by 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.

Holes in leaves and flowers are caused by Japanese beetles, pests that can seriously damage foliage. Adults of these insects devour leaves, stalks, and flowers of nearly 300 plant species. Their larvae feed on the roots of the plants. Handpick adult beetles into a can of soapy water but make sure to wear gloves as Japanese beetles are blister beetles. Apply parasitic nematodes to the soil to limit beetle grub populations. Use pyrethrin powder or neem oil as a last resort.

If a plant has absorbed more water than it needs, it can cause the plant’s cells to expand and stress. Often, these cells are filled to the point of rupturing. Burst cell damage is called edema. You can check for signs of edema by noticing any blisters or lesions on the plant. Eventually, these lesions will turn to dark or even white scar tissue. Another sign of edema is indentations on the top of leaves.

Reddish to brown lines on leaves are caused by thrips. Thrips are tiny, yellow to black flying insects. They hide under leaves and inside flowers. Severely infested plant parts should be pruned off and destroyed. Control thrips by introducing lady beetles or lacewings. Insecticidal soap helps in severe infestations.