At tight branch crotches, small wounds can form from tree movement, resulting in ooze that is commonly seen in this location.
Fruit
Western flower thrips visiting a plum (circled on left) and damage to nectarine fruit on right.
Peach buds sliced in half, with the brown and dead flower ovary on the right killed by frost, and healthy flower on the left.
San Jose scale is an immobile insect that feeds on bark and fruit. Oil targets the overwintering nymphs on the bark.
Peach twig borer feeds on succulent twigs and ripening fruit. It overwinters on the bark, so the oil will smother the tiny larvae.
Pear bud swell
Pear psylla causes browning of pear foliage. It overwinters as eggs near buds.
Peach bud swell
Fire blight infections on bark will ooze bacteria in spring. Copper prevents the bacteria from multiplying.
Cherry bud swell
Fall cankerworm overwinters as eggs that can be suffocated by oil. The larvae can feed on fruit and leaves.
Brown mite is a cool-season mite that is uncommon. It overwinters as eggs on the tree.
Apricot bud swell
Blister mites overwinter in bud scales. Their feeding causes brown spots to form in the summer.
Apple budburst