199fungicides and biofumigation (Deadman et al. 2006 ). Pre-plant fumigants are effec-
tive in reducing soil-borne inoculum. Fungicide-treated seed is an important tool
against certain seed and seedling diseases. Although chemical pesticides provide
quick, effective and economic management of plant diseases, continuous use of the
same pesticides over a long period for the same pathogens may result in the devel-
opment of resistant strains of the pathogens as well as cause various environmental
and health problems. Such pesticides also cause imbalances in the microbial com-
munity and inactivate soil-borne antagonists of pathogens (Pose-Juan et al. 2015 ;
Stott and Taylor 2016 ).
Selection of the best management strategy will depend on some criteria includ-
ing disease threshold, availability of resources, and applicability to the implementa-
tion area. Strategies can be divided into three types: cultural, biological and chemical
control which are discussed below.
5.1 Cultural Practices
Cultural practices are commonly used to reduce pathogen inoculum and diseases.
These include crop rotations, management of irrigation, good sanitation, use of
disease-free seeds and seedlings, the use of soil solarization and soil amendments.
Crop rotation with non-susceptible crops helps reduce pathogen levels which may
build up in the soil when the same crop is grown in the same field year after year
(Lamour and Hausbeck 2003 ).
Solarization of field soils is a widely used method for controlling soil-borne plant
diseases (Deadman et al. 2006 ; Farraq and Fotouh 2010 ; Carrieri et al. 2013 ). Soil
solarization exposes the soil to heat generated from wavelength sun rays trapped by
the polyethylene cover. It is practiced mainly in summer when high ambient tem-
peratures can exceed 40 °C, especially in many dry environments. Soil solarization
is a good practice for the management of several soil-borne diseases by reducing the
initial pathogen inoculum (Deadman et al. 2006 ; Farraq and Fotouh 2010 ; Carrieri
et al. 2013 ). The efficacy of control using solarization can be improved when used
in combination with cabbage (Brassica oleracea L.), which helps releases gasses
that act as a biofumigant to soil (Deadman et al. 2006 ). Of four chemical and physi-
cal treatments, Al-Samarria et al. ( 1988 ) found soil solarization to be best control of
P. aphanidermatum and some other soil pathogens in Iraq. Solarization of potting
media effectively eliminated the primary inoculum of many plant pathogenic fungi
(Al-Sadi et al. 2015c).
Soil replacement is another cultural practice for managing soil-borne fungal
inoculum in some growing systems in arid environments. It is practiced by exclud-
ing the top layer (~30–60 cm) of previously-cultivated soil and replacing it with
uncultivated soil imported from outside the farm (Al-Sa’di et al. 2008b). In addition,
irrigation management is another control tactic for reducing the incidence of soil-
borne diseases (Clarke et al. 2004 ) by reducing the rate of reproduction of patho-
gens and the movement, germination and growth of fungal spores.
Epidemiology and Management of Fungal Diseases in Dry Environments