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Control. Since there are no conidia, control is easy theoretically by
removing and destroying all flowers as they fade, not allowing any to
remain on the ground. From a practical standpoint this is almost impossible. Camellias bear many blooms over a long period, and cleaning up
is sure to be haphazard. Treating the soil with a suspension of Fermate,
using 6 pounds of the black powder per 1000 square feet, just before
apothecia are due (usually January) inhibits their formation. It is possible that calcium cyanamide granules would also be effective. In some
of my experiments they entirely prevented apothecial production by the
azalea fungus, without injury to the plants, even though they did not
reduce the amount of disease because of conidia arriving from other
plants. With camellias, where apothecia remain the sole source of inoculum, the story should be different.
Camellias purchased from areas where flower blight is known should
be bare-rooted-taken out of soil and rewrapped with peat moss or sphagnum-and all flower buds showing color removed. Do not take camellias
home from flower shows for propagating. The disease has sometimes been
present in blooms flown in for exhibition.
BEAN BLIGHTS.
There are several rather similar bacterial blights of bean.
Common blight (Xanthomonas phaseoli) starts as small, translucent, water-soaked spots on leaves; the intervening tissue turns yellow
and dies, giving large brown areas with yellowish borders. Leaves become
ragged in wind and rainstorms; reddish-brown streaks appear in stems,
and they may break over. Pod lesions are dark green, later dry, sunken,
and brick red, sometimes with a yellowish encrustation of bacterial ooze.
White seeds turn yellow, have a wrinkled, varnished appearance. Fuscous blight can scarcely be told from common and is caused by a variety
of the same bacterium. Halo blight (Pseudomonas phaseolicold) differs in
having a light halo around the spots.
Control. Use seed grown in the Far West where blight is rare. Clean
up all old bean refuse.
BOTRYTIS BLIGHTS
are gray mold diseases familiar to most gardeners.
Different species of Botrytis, a fungus, blight lilies, tulips, peonies,
and many other flowers.
GRAY MOLD BLIGHT (Botrytis cinerea).
This is a ubiquitous, not strictly
parasitic, species attacking buds, blossoms, leaves, and fruits in
moist weather, covering them with clusters of spores which give the graymold effect. The disease is common on primroses, begonias, and geranium
in greenhouses but disappears when these plants are brought into the dry
air of the average living room. It is common on fading garden flowers,
on roses, marigolds, calendulas, and zinnias.
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Types of Garden Enemies
