Agriculture Reference
In-Depth Information
New insights into disease epidemiology are
emerging through development of models to
predict incidence and severity of take-all
(Ennaïfar et al., 2007) and eyespot (Colbach et al.,
1999). These models provide a tool to more effec-
tively identify and combine the most effi cient
methods that individually provide only partial
disease control (Ennaïfar et al., 2005). They also
provide a tool to more effectively respond to soci-
ety's demand to reduce the use of pesticides. One
example is the current multidisciplinary emphasis
on developing crop rotation and management
systems to control eyespot, based on the use of
multiresistant, hardy winter wheat cultivars in
France (Savary et al., 2006).
Extensive research continues to be focused
on the pursuit of biological control and en-
hanced soil suppressiveness for diseases such as
take-all, common root rot, Pythium root rot,
and Rhizoctonia root rot. The greatest focus has
been applied to take-all (Hornby et al., 1998;
Weller et al., 2007). Additionally, B. sorokiniana
is a poor saprophytic competitor, sensitive to
suppression in soils (Bailey and Lazarovits 2003),
and sensitive to several potential biocontrol
agents (Kumar et al., 2002). Likewise, Rhizocto-
nia root rot often becomes severe during the
initial transition from conventional tillage to
no-till (Schroeder and Paulitz 2006), but long-
term no-till farms and annual wheat experi-
ments in the US show little Rhizoctonia disease
(Smiley et al., 1996a; T.C. Paulitz, unpublished
data). Natural suppression to R. solani in cereal
crops has been documented (Lucas et al., 1993;
Roget 1995; Mazzola et al., 1996a). Wiseman
et al. (1996) demonstrated that suppression
was dependent upon a microbial component,
and disease incidence and severity have been
inversely correlated with microbial biomass
(Smiley et al., 1996a). Many other instances of
Rhizoctonia -suppressive soils have been described
(Mazzola et al., 1996a; Sneh et al., 1996) but
specifi c mechanisms for suppression are gener-
ally unknown.
Complementation and collaboration among
regional or national research programs through-
out the world have been highly effective for iden-
tifying and deploying germplasm with higher
levels of resistance to common root rot, eyespot,
and Fusarium crown rot. However, these efforts
are not effectively funded and coordinated.
Greater institutional collaboration and funding
linkages are needed to improve the effi ciency of
coordination between international organizations
such as CIMMYT and ICARDA, and public and
commercial programs in countries where wheat is
an important crop.
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