Corn
smut :essential data |
Disease Name,
Other Names, Crops
Affected Causative Agent, Synonyms,
Description of the Agent Symptoms,
Prevention and Treatment
Other
Comments |
| Disease name |
Corn
smut |
| Other Names |
None known |
Causative Agent
|
Ustilago maydis |
| Synonyms |
- Caeoma zeae
- Lycoperdon zeae
- Uredo maydis
- Uredo segetum zeae-maydis
- Uredo zeae
- Uredo zeae-maydis
- Ustilago carbo-maydis
- Ustilago mays-zeae
- Ustilago segetum mays-zeae
- Ustilago zeae
- Ustilago zeae-maydis
|
| Crops Affected |
Maize (corn in the US),
sweetcorn |
| Description of the Agent |
The fungus is
a member of the Basidiomycetes, the club fungi, and within them it
is a member of the smuts (Ustilaginaceae). It can grow in two manners
dependent upon conditions and is therefore known as a dimorphic fungus.
Under relatively good conditions, typically on dead plants, it grows
as single-celled or yeast-like form. The other form, the filamentous
mycelial form occurs when the fungus is mating and invading a plant.
Mating is essential for maintenance of the filamentous form. The filamentous
form invades the plan through structural pores such as the stomata
of leaves or the silk. When it enters the corn cob it stimulates growth
of tissue to form disease structures known as galls. Inside the galls,
sturdy spores known as teliospores, which are the product of the sexual
cycle that gave rise to the mycelium, are generated. These as dispersed
by the wind and can overwinter to cause infection the following year. |
| Symptoms |
The most obvious
symptom is the appearance of gall structures in the ear. Galls can
be seen on the leaves of young seedlings, which can be killed outright.
Otherwise, they can be seen on buds, tassels, leaves and stalks. They
appear greenish-white when young. |
| Prevention and Treatment |
Corn smut can infect
corn plants under almost any circumstances and control is difficult.
There is relatively little natural resistance to the disease. Early
destruction of infected plants and crop rotation may be helpful. Losses
can be extensive. |
| Other Comments |
Ustilago maydis is unique amongst biological weapons in
that it is not only edible, but considered highly desirable. In
Mexico, galls on sweetcorn are known as huitlacoche and
they can be more valuable than the plant itself. Farmers may therefore
try to spread the disease when plants are seen to be infected.
U. maydis has several features that make it an interesting
model for the study of dimorphism. A small but dedicated research
community has developed an extensive body of knowledge on the organism.
This knowledge, which has been publiehed in the scientific literature,
may be used to better understand the mechanism of pathogenesis and
perhaps in the development of more aggressive variants of the pathogen.
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