292 M. BABADOOST
sporangiophores), have long pedicels, and are spherical to elongate with
a tapering base (Mchau and Coffey 1995).
Significant differences in virulence (degree of pathogenicity) and
genetics among isolates ofP. capsicihave been reported (Ristaino 1990;
Islam et al. 2004). Several methods can be used to study the genetic
variation ofP. capsiciand other fungi. Sequencing and/or restriction
digest of internal transcribed spacers (ITS) regions can be used for
species identification. A specific PCR primer (Pcap) has been devel-
oped that can be used with ITS primers to specifically amplifyP. capsici.
Inter-simple sequence repeats (ISSR) amplification, amplified fragment-
length polymorphism (AFLP), allozyme genotyping, and restriction
fragment-length polymorphisms with a probe can be used to study
genetic variation among populations ofP. capsici(Lamour and Haus-
beck 2001; Hausbeck and Lamour 2004; Islam et al. 2004; Bowers et al.
2007; Gobena et al. 2012).
- Host Range. Phytophthora capsiciinfects more than 50 species,
including several weed species, in 15 plant families (Kreutzer et al.
1940; Satour and Butler 1967; Gubler and Davis 1996a; Lee et al.
2001; Hausbeck and Lamour 2004; Tian and Babadoost 2004; French-
Monar et al. 2006). Among the major hosts of P. capsici are red
and green peppers (Capsicum annuum), black pepper (Piper nigrum),
acorn squash (Cucurbita moschata), blue Hubbard squash (Cucurbita
maxima), cantaloupe and honeydew melon (Cucumis melo), cucum-
ber (Cucumis sativus), gourd (Cucurbita moschata), jack-o-lantern
pumpkin (Cucurbita pepo), processing pumpkin (Cucurbita moschata),
watermelon (Citrullus lanatus), yellow squash (Cucurbita pepo), zuc-
chini squash (Cucurbita pepo), and eggplant (Solanum melongena)
(Tian and Babadoost 2004). - Disease Cycle and Epidemiology. Phytophthora capsiciis a soil-
borne pathogen and survives between crops as oospores in soil or
mycelium in plant debris. Oospores are resistant to desiccation, cold
temperatures, and other extreme environmental conditions, and can
survive in the soil, in the absence of a host plant, for 4 years (Pavon
et al. 2008). Oospores germinate and produce sporangia and zoospores
(Fig. 6.2). Zoospores are released in water and dispersed by irrigation or
surface water. Zoospores are able to swim for several hours and infect
plant tissues. Zoospores first lose their flagella and then encyst and form
a cell wall, germinate, and infect plant tissues (Erwin and Ribeiro 1996;
Gobena et al. 2011). Abundant sporangia are produced on infected tis-
sues, particularly on infected fruit. Sporangia are dispersed by water or