Environmental Engineering Reference
In-Depth Information
pathogens cause plant diseases, which vary widely according to geo-
graphical location and climatic conditions. Specific information about,
and identification of, particular diseases and methods for their control
should be sought from local plant-protection services. The discussion
here will be limited to basic concepts of how a disease develops, man-
agement practices that can reduce disease occurrence, and the major
methods used to eradicate diseases from infected turf.
Turf-grass diseases develop only when pathogen, susceptible host
and suitable environmental conditions are present at the same time.
Disease will not develop if only two of the three factors are present. For
example if the pathogen and conditions favouring its development are
present, but the turf-grass is tolerant to the pathogen, disease will not
occur. Similarly, disease will not develop if the turf-grass is susceptible to
a pathogen but
the environmental conditions are not
favourable
(Fig. 11.8).
Disease diagnosis
Before any control is attempted, the disease must be properly diagnosed.
Although diseases are sometimes responsible for poor turf quality, they
may not be the only cause; other factors, such as insects, drought, exces-
sive water or fertilizer burn can cause symptoms that may be confused
with signs of disease. Some turf-grass diseases are very typical and easy
to identify, but others are not. Some disease-causing fungi produce abun-
dant powdery spores or weblike mycelia, and sometimes obvious and
No disease
Disease
Pathogen
Susceptible host
Susceptible
host
Pathogen
Favourable
environment
Favourable
environment
Fig. 11.8. Turf-grass diseases develop only when pathogen, susceptible host and
favourable environmental conditions are all present at the same time.
