What Is Wrong With My Pieris Shrub?

Are the leaves mottled and have shiny, black flecks on the undersides?

Do the leaves have notched edges?

Are the leaves yellow and covered with small bumps?

Are there any reddish-brown dead spots with gray centers on leaves?

Does the shrub lacks vigor with wilted or discolored leaves that may drop prematurely?

Small tarlike spots on undersides of the leaves are caused by lace bugs. Remove debris in springtime and in fall to deter overwintering of these small insects. If the infestations are severe you can control them by spraying pyrethrin, insecticidal soap, or superior oil.

Notched edges on the leaves are caused by Black vine weevils. The wingless, black bugs with yellow markings are adults that feed on the leaves. To control them, spread a drop cloth around your shrub and shake it so the adults drop. You can get rid of them after that. Spray leaves several times with pyrethrin for major infestations.

Yellow leaves covered by small bumps are caused by scales. These tiny, shelled insects often feed on the undersides of the leaves, causing an unhealthy appearance with yellowish blotches on the upper leaf surfaces. Scrape off minor infestations with your fingernail. Prune out badly infested growth, or use a soft brush and soapy water to gently scrub the scales off the stems. Control scales by spraying insecticidal oil during the growing season.

Leaf spot diseases are also known to attack Pieris, causing reddish-brown dead spots with gray centers. The fungus spreads by moving water, so avoid overhead irrigation when possible. Apply approved fungicides in severe cases per label instructions.

The fungal disease Phytophthora attacks numerous water-logged garden shrubs. The fungus attacks the roots and progresses to the crown, eventually killing the plant. Plant the shrub crown slightly above ground level and amend poor soils with plenty of organic matter. Avoid wetting tree trunks when irrigating.

Pieris japonica needs acidic, moist but well-drained soil and protection from harsh winds and sun. High pH soils that lack organic material inhibit plant growth and cause the foliage to yellow. Extended periods of direct sun daily burn the leaf edges and invite insect pests that feed on them. Poorly-drained soils and over-watering prevent air exchange by the roots and cause fungal problems.