PINK SNOW MOLD (Calonectria (Fusarium) nivale).
The name comes
from the gelatinous pink spore masses on leaves dying in circular
patches up to a foot across. The fungus grows under snow cover, or in
melting snow or in cold winter rains. A mixture of calomel and bichloride of mercury at the rate of 2 to 3 ounces per 1000 square feet is satisfactory, applied about December. Tersan is also used.
Rusts belong to the Uredinales, a highly specialized order of the Basidiomycetes or mushroom fungi. Many of them have a complicated life
history with 5 different spore forms and live part of their lives on one
plant and the remainder on a totally different type of plant. The classic
example is wheat rust with barberry as alternate host. Here control
measures have centered around eradication of the common barberry and
production of resistant varieties of wheat. The situation is made more
difficult by the rust constantly developing new strains to infect hitherto
resistant hosts; it keeps one jump ahead of the plant breeders.
As home gardeners you need not know all the thousands of rusts and
their life cycles, but you should at least know what a rust looks like and
not be misled by any reddish discoloration of a leaf. Rust spores are
produced in pustules, either on leaves or stems. Common summer urediospores are reddish, and so these pustules are rusty in color, orange red in
some species, chocolate brown in others. Late in the season winter spores
may be formed in black pustules.
ASPARAGUS RUST (Puccinia asparagi).
Numerous brownish pustules in
summer and black spore masses in autumn, in the same or new
pustules, appear on stems and leaves. Plants mature too early, and next
season's yield is reduced.
Control. Eliminate volunteer plantings around the bed. Use resistant
varieties, Mary Washington or Martha Washington. These may rust
slightly but are superior to other types.
BEAN RUST (Uromyces phaseoli var. typicd).
True bean rust is quite
different from bean anthracnose so often erroneously called rust.
Reddish-brown pustules are formed in groups, usually on underside of
leaves with upper surface turning yellow above the pustules, sometimes
on stems and pods. There may be considerable defoliation. Kentucky
Wonder pole beans arc very susceptible. Spores are spread on tools and
clothing and can even survive the winter on old bean poles.
Control. There are some rather resistant varieties including a rust-
resistant selection of Kentucky Wonder. Dusting with sulfur is fairly
BLACKBERRY RUST (Gymnoconia peckiana).
This orange rust infects blackberry, dewberry, and black raspberry, bright orange spores covering underside of leaves in spring. The mycelium lives perennially inside
the bush so there is no control by spraying. Infected plants never recover and should be dug out and burned as soon as possible. Eldorado
variety is highly resistant.