Biology Reference
In-Depth Information
Molds
Botryosporium
The word mold, or mould, has many meanings.
The first one given in Webster is “a growth, often
woolly, produced on various forms of organic
matter, especially when damp and decaying, by
saprophytic fungi.” Leaf mold is organic matter
reduced to friable earth by these saprophytic
fungi. When rhododendrons are fed with
a fertilizer having a cottonseed meal base, one
can often see a moldy growth, showing that ben-
eficial organisms are at work breaking down the
material for plant use.
Some of these saprophytic fungi have
a harmful, parasitic phase. The common
black bread mold,
Rhizopus nigricans
, causes
soft rot of sweet potatoes and “leak” of straw-
berries and grapes.
Penicillium
spp., the common
blue molds on jellies, cause a decay of citrus and
other fruits. Such diseases are discussed under
Rots.
The word mold is used loosely to cover any
profuse fungus growth on the surface of
plant tissue. See Blights for a discussion of
Botrytis gray mold, so common on many
plants; see Leaf Spots for Alternaria brown
molds and Ramularia white molds, and for
moldy leaf spots due to
Heterosporium
and
Pleospora
; see Sooty Molds for the black
growths on insect exudate; and see Snowmold
for turf diseases.
Deuteromycetes, Hyphomycetes
Conidiophores, tall, slender, hyaline producing
numerous lateral branches of nearly equal length,
each producing two or more secondary branches
that are enlarged at the tip and bear heads of
conidia; spores one-celled, hyaline; saprophytic.
Botryosporium pulchrum
Leaf Mold
on
tomato, also geranium (pelargonium), occasional
in greenhouses.
Chalara (Chalaropsis)
Deuteromycetes, Hyphomycetes
Mycelium at first hyaline, then greenish; two
types of conidia-macroconidia or chlamydo-
spores, olive green, thick-walled when mature,
sessile or borne in short conidiophores in com-
pact groups; endoconidia, hyaline, formed inside
end cells of a dark endoconidiophore and
extruded in chains.
Chalara thielavioides (formerly
Chalaropsis
thielavioides
).
Black Mold
of rose grafts. Manetti
mold, usually on grafted roses, sometimes on
budded roses in nursery fields. The fungus
