The northern Queensland papaya industry (latitudes 18.16o
S to
17.00o
S) comprises approximately 90% of all papaya (Carica papaya)
grown in Australia (Diczbalis et al. 2012). Phytophthora-related
diseases (e.g. root rot, stem rot and fruit rot) caused by P. palmivora
are a significant constraint to the profitability and further expansion
of the Australian papaya industry which has an estimated
value of $18e25 Million (Diczbalis et al. 2012). These diseases are
particularly damaging for growers on the wet tropical coast of far
north Queensland (Diczbalis et al. 2012) where the average annual
rainfall is in excess of 3000 mm with a distinct wet season from
January to April. Following periods of heavy rainfall, entire columns
of fruit can be lost to Phytophthora fruit rot. Mature fruit infected
with P. palmivora become covered with off-white mycelium that
produces masses of sporangia which contain highly infective zoospores
(Hunter and Buddenhagen, 1969).