© Springer International Publishing AG 2016 187
M. Farooq, K.H.M. Siddique (eds.), Innovations in Dryland Agriculture,
DOI 10.1007/978-3-319-47928-6_7
Epidemiology and Management of Fungal
Diseases in Dry Environments
Abdullah M. Al-Sadi
1 Introduction
Fungi are among the most common microorganisms in nature. They have cell walls
consisting of chitin (except for the pseudo-fungi, e.g., Oomycetes) combined with
other carbohydrates. Most fungi have hyphae—cylindrical, thread-like structures—
that collectively form a mycelium. The mycelium can be very complex; some can
colonize the soil and cover several hectares (Smith et al. 1992 ).
Most fungal species are saprophytic, playing important roles in stabilizing soil,
decomposing waste material, producing antibiotics, acting as biocontrol agents, and
promoting plant growth and development (Abed et al. 2013 ; Al-Sadi et al. 2015d,
Guo et al. 2015 ; Matsushita et al. 2015 ; Van Geel et al. 2015 ). However, several
fungal species are plant pathogens, causing various symptoms and losses in plants,
the effects of which vary from limited effects on growth to plant destruction.
Fungal pathogens have long been considered as highly variable organisms,
apparent both in field collections (Perkins 1991 ) and from the behavior of single
isolates in the laboratory (Caten and Jinks 1968 ). Variation in some traits have been
reported including aggressiveness, morphology and genetic makeup (Harvey et al.
2000 ; Harvey et al. 2001 ; Garzon et al. 2005a, b). Fungal species exhibit different
levels of genetic diversity which can vary from species to species (Garzon et al.
2005b), region to region (Harvey et al. 2000 ), host to host (Harvey et al. 2001 ) and
between different production systems (Al-Sadi et al. 2013 ).
Fungi exist in tropical, temperate and dry environments. Many fungal pathogens
produce resistant survival propagules and have wide host ranges which help them to
survive in soil and on plant debris for extended periods of time. Mechanisms by
which fungal pathogens spread between different places are important features that
A.M. Al-Sadi (*)
Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos
University, 34, AlKhoud 123, Oman
e-mail: [email protected]