EPWS 310 - PLANT PATHOLOGY
General Blights
- Botrytis and Sclerotinia.
Postharvest
Diseases Study on your own
Pages
510-514, 546-550, 553-561
General
Blights.
Gray Mold - Botrytis cinerea
The most common foliar
disease of greenhouse crops throughout the world. The disease is serious under
cool, humid conditions particularly when there is no drying period during the
day (ie greenhouses).
The disease is
characterized by a gray felty mycelial growth over all herbaceous parts of the
plant. It affects pine seedlings, strawberry (in the field), all vegetables,
flowers etc.
It is also a
storage rot if present in stored vegetables stored at too high humidity.
Can also cause
damping-off.
DISEASE CYCLE -
Figure 11-97
Overseasons as
sclerotia and mycelia and on weeds (near greenhouses). The conidia are abundant
and can infect directly as well as through wounds. It is a necrotroph.
Can be spread by
seed contamination and by contaminated potting mix.
Control?
Botrytis
usually has no perfect stage but if present it is Sclerotinia.
WHITE MOLD - Sclerotinia
This fungus
causes white mold and blight diseases of many vegetables and ornamentals. Very
wide host range. All herbaceous parts of the plant are affected and under humid
conditions white cottony mycelium develops on all parts of the plant. It is a
soil invader.
Can cause a soft
rot on tubers or corms and will spread by mycelial growth on the soil surface
if humid enough.
If you ever find
a white cottony mycelium on your green beans after a few weeks in the fridge
this is it!
DISEASE CYCLE
Figure 11-123.
Survives as
sclerotia and is very aggressive.
Control?
Not a major part
of this course just need to know the main pathogens.
Rhizopus - Mucorales: Zygomycete
Alternaria - Ascomycete anamorph
Fusarium - Ascomycete anamorph
Geotrichum - Ascomycete anamorph
Penicillium - Ascomycete anamorph
Aspergillus - Ascomycete anamorph
Sclerotinia - Ascomycete anamorph
Control?
Mycotoxins!!!