Phytophthora chrysanthemi is an oomycete, a fungus-like organism
that reproduces sexually through oogonia and asexually through chlamydospores,
sporangia, zoospores, and mycelia (Naher et al., 2011). Chlamydospores and
oogonia are often the survival structures for Phytophthora spp. (Erwin and
Ribeiro, 1996), but their role in the life cycle of P. chrysanthemi is unknown.
Phytophthora chrysanthemi is tolerant of high temperatures, with optimum growth
in culture at 30°C and growth still occurring at 35°C (Naher et al., 2011; Yang
et al., 2014). It belongs to a small cluster of Phytophthora species in Clade 9
that have been called "high-temperature tolerant" (Yang et al.,
here for the full alert.
We heard from Dr. Jean Williams-Woodward regarding this pest who noted that
this sew species may not be of any more concern than other species already on
the industry's radar. Stay tuned and we will report if more news becomes available.