Article by L.J. Rose, I. Beukes and K. van Zyl
Department of Plant Pathology, Stellenbosch University
F
ungal species within the
also known as red rot) of maize,
Fusarium graminearum
Fusarium head blight (FHB) of wheat
species complex (FGSC)
and barley, and grain mold (GM) of
affect the yield and grain
sorghum. In addition, the FGSC can
quality of numerous eco-
also cause Gibberella stem/stalk rot
nomically important cereal crops in
of maize and can be associated with
South Africa such as maize, wheat,
root and crown rot on cereal crops.
barley, and sorghum. Since 2000 the
The species complex is also known
historic species known as Fusarium
producers of mycotoxins of which
graminearum has been subdivided
deoxynivalenol (DON), nivalenol
into 16 new species based on DNA
(NIV) and zearalenone (ZEA) are the
differences. To date, only six of the
most important.
16 species have been identified on
South African grains. These FGSC
species are responsible for diseases
such as Gibberella ear rot (GER –
Disease symptoms associated
with FGSC infection
The symptoms associated with GER
of maize include white, dark pink or
red mycelial growth originating
from the tip of the maize ear
(Figure 1). Infections typically occur
during the 3-week period after
maize silks have emerged. GER is
generally associated with cooler
areas of South Africa and areas with
higher precipitation during the
growing season, such as the eastern
Free State, Mpumalanga and KwaZulu-Natal.
The symptoms associated with
stalk/stem, crown or root rot of
maize is characterised by discoloured or brown areas in the field
with leaves becoming pale to yellow
Figure 1. Gibberella ear rot (GER) of maize identified by the spread
of pink or purple mycelial growth from the tip of the maize ear .
Figure 2. Characteristic pink to red
discolouration of internal stem/stalk
tissue typical of Gibberella stalk rot.
Photo by I. Beukes
Photo: www.omafra.gov.on.ca/english/crops/pub811/14corn.htm