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Resistance
Although a lot of effort has been made to select hybrids with root,
crown and stalk rot resistance, the main consideration is still yield.
Genotypes with higher yields tend to have bigger ears, which act as
large sinks for carbohydrates in the plants.
The larger ears result in reduced carbohydrate levels in the lower
stem, predisposing the plant to these rots. Therefore, the balance
between breeding for resistance to these rots and breeding for high
yield is a delicate one.
Nutrients and stress reduction
Cultural practices that reduce plant stress also reduce incidence
of stalk rot. Common stress conditions include: High nitrogen, low
potassium fertility, high soil moistures in the mid to late season after
a dry season, moisture stress early in the season and during grain fill
as well as high incidence of leaf diseases.
Physical damage that creates wounds (insects, nematodes, hail) al-
lowing the pathogen to enter the maize plant may also predispose the
plant to root, crown and stalk rot. Reducing plant densities will also
alleviate plant stress.
Chemical control
There are no fungicides available for the control of Gibberella stalk
rot. However, fungicide applications for the control of leaf diseases,
may be beneficial in reducing stress on the plant, thus reducing stalk
rot severity and ultimately lodging.
For further information regarding Gibberella root, crown and stalk
rots of maize or any other maize diseases, contact
Dr Belinda Janse van Rensburg or Prof Bradley Flett at
018 299 6100.
2
2: Typical symptoms of Gibberella root,
crown and stalk rot.