6.  San Jose Scales
Some of the leaves are pale green to yellow and may drop prematurely from weakened limbs. Or they may turn brown and wither, and remain attached to the tree into the winter. The bark is encrusted with small (1/10 inch), hard, circular, slightly raised bumps with dull yellow centers. If the hard cover is scraped off, the insect underneath is yellow or olive. There may be severe limb dieback and entire branches may be killed. The fruit may be marred by specks.