The genus Phytophthora possesses some of the most sophisticated
weaponry known among plant pathogens (Gregory 1983). “Phytophthora
has been seriously recognized as a notoriously difficult genus-
especially for those who wished only to identify an isolate and
were not concerned with taxonomic problems and / or minute details”.
(Waterhouse et al. 1983). The taxonomic key produced by Waterhouse
(1963), a mycologist at The Commonwealth Mycological Institute
at Kew, United Kingdom, was the first to categorise Phtophthora
species into morphological groups. Waterhouse’s separation
of Phytophthora species into six groups based on a series of
morphological and physiological parameters. These parameters
include branching patterns of the sporangiophores, the sporangium
apex, abundance of sporangia on solid media, the non caducous
or caducous nature of sporangia, internal proliferation of sporangia,
production of oogonia and oospores in single culture (homothallic),
production of oogonia and oospores only when mating types are
paired in a culture. (heterothallic)., nature of antheridium,
abundance or absence of oospores on host tissue or in culture,
and for certain species, sporangium shape and dimensions, e.g.
length- breadth ratios, sporangiophores, oogonium size, ornamentation
of oogonial wall, host specificity, and cardinal temperatures.
A revision of Waterhouse (1963) key included six new species
and was based on the same parameters as the 1963 key, but was
presented in a tabular key containing 67 species, 19 of which
have been described since1978 (Stamps et al-1990). It incorporates
the original groups 1-6 of the previous key with the addition
of group 7 for the marine species.
Despite the large number of available keys, the identification of a species
is still considered to be difficult, principally because there are relatively
few morphological features by which the species are distinguished and great
variability and overlapping features exist within species (Leonian 1934,
Erwin 1983). Many Phytophthora species have not been identified into species
(E. M. Hansen et al. 1979).
Broad variability occurs within phytophthora capsici. P.capsici has been described
to include isolates previously designated as P.palmivora MF4 from cacao (Brasier
and Griffin 1979) and black pepper (Piper nigrum). As well as isolates from
Pepper (Capsicum annum).( Tsao and Alizadeh 1988, Tsao 1991, Mchau and Coffey
1994). This study attempts to identify and classify Phytophthora isolated
from black pepper tissue and soil, betel vine tissue and soil as well as
from other hosts.