Irregular yellow blotches appear on the leaves. Eventually the yellow areas turn brown. The leaves may drop prematurely. A shiny, sticky substance often coats the leaves. A black sooty mold may grow on the sticky substance. Tiny green, soft-bodied insects feed on the lower surfaces of leaves but are not easily seen.
Apply an insecticide labeled for aphids as soon as the insects appear. Repeat as directed on the label if the plant is reinfested.