Biology Reference
In-Depth Information
Botryotinia fuckeliana The apothecial stage of
Botrytis cinerea
, the connection having been
made with isolates from grape, apple, celery,
and potato. The name of the conidial stage is
still widely used for the pathogen causing gray
mold blights.
Botryotinia ricini
Gray Mold Blight
of castor
bean,
Soft Rot
of caladium. A pale to olive gray
mold develops on castor-bean inflorescence, and
when fading flowers drop onto stem and leaves,
they are infected in turn.
Botrytis
Deuteromycetes, Hyphomycetes
Fig. 2
Botrytis Petal Spot on Magnolia
Egglike conidia hyaline, one-celled, are formed on
branched conidiophores over the surface, not in
special fruiting bodies (see
Fig. 1
). The arrange-
ment of the spores gives the genus its name, from
the Greek
botrys
, meaning a cluster of grapes.
Flattened, loaf-shaped, or hemispherical black
sclerotia are formed on or just underneath cuticle
or epidermis of the host and are firmly attached to
it. These sclerotia, with a dark rind and light inte-
rior made up of firmly interwoven hyphae, serve as
resting bodies to carry the fungus over winter.
Microconidia, very minute spores that are
spermatia or male cells, function in the formation
of apothecia in the few cases where a definite
connection has been made between the
Botrytis
stage and the ascospore form,
Botryotinia
.
Botrytis
species are the common gray molds,
only too familiar to every gardener. Some are
saprophytic or weakly parasitic on senescent
plant parts on a wide variety of hosts; others are
true parasites and cause such important diseases
as peony blight, lily blight, tulip fire.
Botrytis cinerea
Gray Mold Blight
,
Bud and
Flower Blight
(see
Fig. 2
),
Blossom Blight
,
Gray
Mold Rot
,
Botrytis Blight
of general distribution
on a great many flowers, fruits and vegetables.
There are undoubtedly many strains of this fun-
gus and perhaps more than one species involved,
but they have not been definitely separated.
This gray-mold disease is common on soft ripe
fruits after picking, as any cook knows after
throwing out half a box of strawberries or rasp-
berries. But in continued humid weather the
blight appears on fruits before harvest.
Blackberries in the Northwest are subject to
gray mold. The fungus winters in blighted blue-
berry twigs, and spores infect blossom clusters.
Vegetables are commonly afflicted as seed-
lings grown in greenhouses and in storage after
harvest. If lettuce plants are set in the garden too
close together, they may blight at the base in
moist weather, as will endive and escarole. Gray
mold is common on lima beans, is sometimes
found on snap and kidney beans. In rainy or
foggy periods globe artichoke may be covered
with a brownish gray, dusty mold, with bud scales
rotten. Asparagus shoots are sometimes blighted,
tomato stems rotted.
Some of the ornamentals on which
Botrytis
cinerea
is troublesome are given in the following
annotated list:
African violet
-leaf and stem rot, cosmopoli-
tan in greenhouses.
Amaryllis
-gray mold, mostly in the South, on
outdoor plants after chilling.
Anemone
- occasional
severe rotting of
crowns.
Arborvitae
-twig blight.
Aster
- brown patches in flower heads of
perennial aster; gray mold on flowers of China
aster grown for seed in California.
