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ground parts of a plant can be dispersed by air currents, rain or in-
sects that serve as vectors for the fungi.
Symptoms of
Fusarium
spp. ear rot of maize for example, will vary
greatly depending on the plant genotype, environmental conditions
and disease severity. Infected kernels are often randomly scattered
across the ear or found alongside feeding channels of the stalk
borer. Such kernels appear whitish pink to lavender because of
the fungal growth on them (
Photo 5
).
When the disease is severe, the entire ear will appear white and
weathered with fungal growth present on and in between ker-
nels. Management practices include the use of fungicides for leaf
diseases, sanitation and planting of cultivars with some form of
resistance.
Once a disease is correctly diagnosed, a practical and effective dis-
ease management programme (often with more than one strategy)
may then be recommended. However, with an inaccurate disease di-
agnosis, these actions will be in vain and will incur extra costs for the
producer. To prevent a miss diagnosis, it is strongly recommended
to consult with a trained plant pathologist who can identify the dis-
ease and recommend appropriate treatments.
For more information contact Drs Adrian Abrahams
and Belinda Janse van Rensburg at 018 299 6100.
1: Sunburn symptoms on maize leaves can
easily be confused with northern corn leaf blight.
Photo: Dr Rikus Kloppers, Pannar
2: Insect feeding damage on a maize ear.
Photo: Dr Annemie Erasmus, ARC-Grain Crops
3: Mosaic streak virus of maize.
Photo: Prof Bradley Flett, ARC-Grain Crops
4: Water soaked lesion of an
Erwinia
infection
in a maize stalk.
5:
Fusarium
spp. infection on maize kernels
characterised by a whitish pink cottony growth.
3
4
5
2
1