Figure 2. Lifecycle of Stenocarpella maydis on maize.
bence. Symptoms associated with
sheep often include paralysis and
stillborn lambs. The potential detrimental effects in humans of S.
maydis toxins have not been shown.
Diplodiosis has been reported from
Argentina, Australia, Brazil, South
Africa and the USA.
Management of DER
The management of DER should
form part of an integrated disease
management strategy. This could
include the following:
Planting of resistant cultivars:
Commercial cultivars differ in
their susceptibility to DER, but
none are immune (free of disease). Information on cultivar
response to DER is available from
the Agricultural Research Council
-Grain Crops Institute that conducts the South African National
Cultivar Trial annually under various weather and inoculum conditions.
Application of fungicides: No
fungicides are registered for the
management of S. maydis and S.
macrospora. The use of fungicides in commercial production is
not economically justified due to
low yields and the relatively low
producer prices of maize.
Optimal plant production: Plant
densities should be properly
managed on marginal soils, particularly in areas where there is a
high probability of drought. Fertilisers should be applied according to the yield potential of the
land/area to be planted.
Early harvest of grain: Early harvesting and artificial drying of
grain should be performed
where possible, as this will reduce the time available for the
fungus to grow on the ear.
Cultural practises: Stubble left
in field should be reduced by
partial or complete burying,
burning, grazing, removal or
ploughing-in.
Crop rotation: Rotation of maize
with a non-host crop such as
soybeans, groundnuts, dry nuts,
beans and wheat lowers the inoculum for the season. Increased
periods between maize productions (2-3 seasons) will allow the
natural breakdown of maize
stubble, which reduces the survival of the fungus.
Figure 3. A cross section of an infected ear shows black spore producing bodies (pycnidia) at the kernel bases (www.pioneer.com).