Leaves Rot - Over-watering
Lamb's ears sometimes develop matted, rotting foliage in the center of large clumps or underneath the stems. This happens when moisture accumulates due to excessive rain, poorly drained soil or overcrowding. Gently clean out the rotting foliage. Usually the improved air circulation solves the problem. Divide overlarge clumps as described above.
Lamb's Ears have no known insect pests.
Lamb's Ears have no serious disease problems, but you may sometimes have to deal with one of those listed below.
Leaves Spotted Or Blotched - Fungal Leaf Spots
Many kinds of leaf spots are caused by fungi that thrive on moist leaf surfaces and cause transparent to brown or black spots that disfigure the leaves. Some fungal spots are surrounded by flecks or black dots, their spore-bearing fruiting bodies. Often spots come together to form larger patches of dead tissue. Pick off and discard infected leaves. Remove dead plant debris promptly from the garden to reduce over wintering spore populations. Dig up and discard seriously infected plants together with the soil of the root ball. Spray foliage at weekly to 10 day intervals with wettable sulfur or Bordeaux mixture, particularly in wet weather. (Watch for leaf discoloration with the latter.) Clean up garden area well in the fall to deny disease spores a place to overwinter. For more information see the file on Controlling Fungal Disease
Powdery Spots On Leaves - Rust
Rust diseases caused by various fungi produce pale yellow areas on upper leaf surfaces and powdery spots of fruiting bodies on undersides directly beneath. Infected stems and flowers may be seriously deformed. These symptoms may be difficult to detect on the silvery foliage of lamb's ears, so inspect closely any leaves that do not look normal. Remove any infected leaves as soon as possible. Remove and destroy all garden debris before plants start to grow in the spring. Control weeds in and around the garden. Control insect pests which transmit this disease with pyrethrum or rotenone. Prevent rusts with periodic sprays of wettable sulfur on vulnerable plants, starting several weeks before the disease normally appears. Space plants widely apart for good ventilation, and avoid wetting the foliage when watering. For more information see the file on Controlling Fungal Disease
Plants Stunted, Yellowed; Root Lesions - Nematodes
Nematodes are not insects, but slender, unsegmented roundworms. Most are microscopic-sized soil dwellers. They have piercing-sucking mouthparts and feed on cell contents. Several kinds of nematodes occasionally attack leaves or roots of lamb's ears. Infested plants look sickly, wilted or stunted, with yellowed or bronzed leaves. They decline slowly and die. The roots are poorly developed, have little knots in them, and may be partially decayed. Control the pests by digging up and discarding severely damaged plants, and by adding lots of compost or moldy, semi-decomposed leaves if they are available, to the soil to encourage beneficial fungi that attack nematodes. If the pests are a recurrent problem, do not plant lamb's ears in that location. For more information see the file on Controlling Nematodes