2011999 ). Quality compost can serve as a source of high populations of beneficial
microorganisms which are naturally recolonized or artificially inoculated (Al-Sadi
et al. 2015c). These organisms suppress pathogenic propagules using different
mechanisms such as competition for nutrients, antibiotic production, parasitism
against pathogens and activation of disease-resistance genes in plants (Hoitink and
Boehm 1999 ). In addition, they stimulate plant growth by modifying soil condi-
tions. High microbial biomass is responsible for releasing nutrients from organic
matter and increasing nutrient availability to crops.
Disease resistance in plants is a cost-effective way to control diseases. It is com-
monly used for the management of several plant diseases caused by fungal patho-
gens including resistant cultivars to wheat diseases (van Wyk et al. 2007 ;
Guzmán-Valle et al. 2014 ; Singh et al. 2015 ).
Defense responses deployed by host plants in the reaction to pathogen invasion
are an important component of the integrated management of plant diseases. They
can reduce or eliminate the need to use chemicals and biological formulations and
therefore reduce the costs and environmental hazards associated with increased
chemical applications.
Increasing the defense response in plants to infection by fungal pathogens has
been attempted. For example, by using non-pathogenic microorganisms such as
Fusarium oxysporum Schltdl. strain Fo47 (Benhamou et al. 2002 ), compost (Lievens
et al. 2001 ) and silicon (Chérif et al. 1994 ; Al-Sadi et al. 2010b). Silicon reduced the
severity of some cucurbit diseases including powdery mildew (Menzies et al. 1992 ;
Heckman et al. 2003 ) and wilt (Chérif et al. 1994 ).
5.3 Chemical Control
Chemical control is a widely used practice for managing diseases in different parts
of the world (Wiersma and Motteberg 2005 ; Chung et al. 2009 ; Nallathambi et al.
2009 ; Agostinetto et al. 2015 ). Several protectant and systemic fungicides are used
to control fungal diseases. Fungicides vary in their characteristics and efficacy and
are used to treat seeds, soil, foliage and fruits.
Seeds are usually treated with some protectant fungicides to prevent infection of
seed in soil (Harman et al. 1989 ) and to reduce the level of disease in crops. However,
soil treatments are typically required for transplanted seedlings and plants, while
foliar and fruit applications can help reduce aerial infections and postharvest
diseases. Pre-plant fumigants are effective for reducing soil-borne inoculum.
However, there are increased restrictions on some fumigants due to their risks. The
type of fungicide/fumigant used usually depends on the invading pathogen and
other management strategies used on the farm.
Fungicides are more effective for managing plant disease than other strategies.
However, there are several environmental and health risks, including negative
effects on beneficial microorganisms and risks to wildlife. Some problems have also
arisen with the continuous use of fungicides, such as the development of fungicide
Epidemiology and Management of Fungal Diseases in Dry Environments