Control. Sanitation is most important. Cut down and burn old stalks
in fall. Remove then and again in early spring all leaves showing signs
of rust. Dust with sulfur, starting very early in the season.
QUINCE RUST (Gymnosporangium clavipes).
The fungus alternates between eastern red-cedar and a few other junipers and quince, Japanese quince, apple, amelanchier, hawthorn, mountain-ash, and pear.
The mycelium is perennial in the outer bark of the juniper host which
may show a slight swelling but forms no galls. The fungus is probably
most conspicuous in summer on English hawthorn, covering the hips
with white papery projections around orange spores. There is no very
ROSE RUST (Phragtnidium disciflorum).
Present in New England and
northern New York but more prevalent in California and the Southwest. Summer spores are orange in very small cushions on underside
of leaves; winter spores are black. Infection occurs after the foliage is
continually wet for 4 hours.
Control. Fermate is usually recommended, but results seem to be uneven.
SNAPDRAGON RUST (Puccinia antirrhini).
The pustules are chocolate brown
and very powdery, with upper surface of leaf yellow in affected
areas; plants may be stunted.
Control. AH seed catalogues offer resistant varieties. If you are foolish
enough to plant the other kind, then spray regularly with Parzate or
WHITE PINE BLISTER RUST (Cronartium ribicola).
Infected branches turn
a conspicuous red-brown and swollen cankers are formed at the
base. In spring these are covered with blisters filled with orange-yellow
masses of spores which infect currants, gooseberries, and wild species of
Ribes. In late summer another type of spore returns to the pine.
Control. Black currants are eradicated entirely and red currants and
gooseberries removed within 300 feet of pines. If limb cankers are 6
inches or more away from the trunk, diseased limbs can usually be cut
out and the pine saved. Ornamental pines in cities are not often attacked;
soot and fumes are unfavorable to the fungus.
Sawflies are related to bees and wasps, in the insect order Hymenoptera,
the adults having 2 pairs of wings hooked together. But we almost
never see these adults; we are concerned with depredations of the larvae which either resemble small slugs or are like caterpillars except
for having more prolegs, 6 to 8 instead of 5, and a habit of hooking
their rear end around a twig while feeding. The name comes from the
sawlike ovipositor the female uses to slit stems or leaves when she lays
eggs. Most sawflies are fairly readily controlled by spraying with either
DDT or lead arsenate at the proper time.