Agriculture Reference
In-Depth Information
Teich (1987) observed a higher FHB infection in Ontario, Canada, with the application of
ammonium nitrate than when urea was applied. In other studies the application of different
types of nitrogen fertilizer did not lead to any significantly different results (Lemmens et al.,
2004). Potassium, phosphorus and pH did not appear to affect the DON content to any great
extent (Teich and Hamilton, 1985).
The isolation of
Fusarium
species, pathogenic to winter wheat from common grasses
(Cassini and 1970; Lager and Wallenhammer, 2003) and broad-leaved weeds (Jenkinson and
Parry, 1994), suggests that an effective weed control can reduce the inoculum. Moreover,
weeds can also favour
Fusarium
infection by modifying the microclimate and increasing heat
and humidity in the canopy.
Sowing date could have an indirect effect on the FHB infection. It in fact influences the
moment in which the flower appears, a moment which can sometimes coincide or not with the
Fusarium
spore release (Lacey et al., 1999). Caron (1993) reported that a late sowing date
favoured the development of head blight, whereas an early sowing date favoured the
development of foot rot.
Severe infections of head blight have been reported with high planting densities
(Mesterházy, 1995), which could increase the humidity of the canopy (Deadman and Cooke,
1997), favouring spore germination. On the other hand, Champeil et al. (2004b) suggested
that an elevated density of the canopy could be a greater obstacle to spore dispersal.
Nevertheless, at the moment, the magnitude of the effects that these agricultural practises
have on FHB disease development, if indeed there is one, remain unclear and each one of
them needs to be evaluated alone and in combination with the other crop techniques.
Although only a few studies have been conducted on the effects of agricultural practices, it is
possible to say they are probably very dependent on the climatic and soil conditions of each
region. Thus, it is difficult to extrapolate the results obtained for these preventive measures
from each wheat growing area and to generalize them for application in other regions.
In the future, biological control could be used to offer an additional strategy and as part
of an integrated management of FHB. In vitro assays, trials in glasshouses and under field
conditions have shown that some bacteria included in the genera
Bacillus
and
Pseudomonas
,
some yeasts belonging to the genera
Rhodotorula
,
Sporobolomyces
and
Cryptococcus
and
some fungi of the genera
Trichoderma
, are able to reduce
F. graminearum
growth
(Fernandez, 1992; Schisler et al., 2000; Schisler et al., 2002; da Luz et al., 2003; Khan et al.,
2004). These potential biocontrol agents could be applied at wheat anthesis in order to
prevent
Fusarium
infection, when conditions for the disease exist. In a recent work under
greenhouse conditions, Palazzinia et al. (2007) observed a significant reduction in DON
contamination in wheat grain inoculated with bacterial strains. Unfortunately, under field
conditions, the biological control effects have been shown to be too variable (McMullen et
al., 2002).
4.5. Effect of Crop Management Systems
In order to optimise the control of FHB and DON contamination of grain, it could be
interesting to evaluate the effect of different crop management systems.
At present, there is a lack of information about the effects of entire cropping systems on
FHB.
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