Lower branches of the blue and Norway spruces brown-off and die, progressively upward. Pitch exudes and cankers appear at the edges of dying bark, where small black fruiting bodies can be seen. This is Cytospora canker. Control: Prune all affected branches when weather is dry; spray repeatedly in spring with a fungicide.

Choke Cherry and cultivated fruit trees. When leaves are scarcely half grown, white webs appear at branch and twig crotches, growing in size daily. Look closely and you will see masses of baby tent caterpillars inside. They defoliate the trees by day, return to the webs every night. Control: Blast the webs with a strong stream and drench the leaves with a mist of strong stomach-contact poison; early next spring look for this caterpillar's cylindrical egg-masses wrapped on twigs and twist them off between thumb and forefinger.

Flowers, leaves, and twig tips suddenly wilt and turn black, as though scorched by a blowtorch. Open, oozing cankers appear on the branches and trunk. Bark blackens and peels. This is fire blight, a bacterial disease. Control: Prune all affected members drastically, trace around and excise smaller cankers, remove and burn all cuttings, paint the wounds with cobalt nitrate, and disinfect tools with bichloride of mercury. Spray infected and neighboring trees repeatedly during early and full blooming with an antibiotic such as agrimycin.

Oaks, Twigs and small branches start dying. Look closely for tiny pits on the deadwood and yellowish or dark-gray round scabs, about 1/16 to 1/10 inch in diameter, on the live bark. These are golden oak scale and obscure scale. They occur separately and can be fatal. Control: Dormant spray with miscible oil, followed by malathion in mid-spring.

Leaves wilt and branches die, their sapwood darkly discolored. Within a year the whole tree may be dead. This is oak wilt, so far uncheckable and incurable. Trees dying of it should be removed and burned promptly. This wilt is caused by a fungus called Ceratocystis fagacearum which enters through lesions, maybe also through the roots. It is earned by flies, beetles, and borers, and maybe is also air-borne. If you hear of oak wilt in your vicinity, repair your oaks' wounds promptly. Spraying with fungicides may help. Ceratocystis can also attack apple, birch, dogwood, sassafras.