Although surface maize residue has been shown to be important for the
development of gray leaf spot epidemics, the conditions under which the crop is
planted also are very important. These conditions affect the production and
dissemination of inoculum from infested maize residue to new infection courts, and
influence events leading to infection and subsequent disease development. Ward
and coworkers (63) reported that in spite of the importance of surface residue, under
environmental conditions favorable for the development of the disease and in areas
5
where the disease was endemic, maize residue played a lesser role in the
development of the disease than weather. The findings of Smith (51) also supported
the idea that the relative importance of surface maize residue depends on the
prevailing weather conditions. Smith (51) and de Nazareno et al (14) suggested that
in areas where the pathogen was endemic, the disease could reach high levels even
in fields with low levels of surface maize residue, once the environmental conditions
were favorable, de Nazareno et al (12) showed that in areas where no-till was
predominant and the disease was endemic, disease gradients from a point source of
inoculum were masked due to the ingress of spores from nearby fields.
Using