Phytophthora hydropathica

The species name hydropathica is composed of the word elements hydro, meaning "water" and pathica, referring to the pathogenicity.[1]

P. hydropathica has been shown to naturally infect a number of different plants including Catawba rhododendron,[1] English Roseum rhododendron,[2] mountain laurel,[1][3] and Laurustinus trees.[4] Studies have shown that the pathogen has the ability to infect other hosts when introduced, such as alder,[5] carnations,[5] cucumber,[6] azaleas,[6] dusty miller,[6] tomato,[6][7] and pepper.[6][7] Symptoms of infection vary with host type.

P. hydropathica is a heterothallic oomycete, meaning that both mating types need to be present in order to sexually reproduce.[8] The A1 mating type has been reported to be highly represented in populations.[1] The species produce plerotic oospores and round antheridia, with observations of the sexual bodies being golden in color.[1] Nonpapillate and noncaducous sporangia are produced, with varying shapes (obpyriform, ovoid, and nearly spherical), and are able to release zoospores.[1] Zoospore release time has been recorded to vary, from release happening immediately after sporangia formation[6] or within hours.[1] Some isolates do not show the ability to produce zoospores.[2] P. hydropathica does produce chlamydospores, present at the end of long hyphae and on short pedicels. Hyphal swelling has also been observed.[1][5]

P. hydropathica is most commonly found in sources of water, such as reserve water ponds,[9] irrigation systems,[2][6][10][11] and rivers.[5] The optimal temperature for growth in the lab is 30 °C (86 °F).[3] In irrigation reservoirs in Mississippi and Alabama the pathogen has the highest counts in the month of May,[9] and has also been shown to have high recovery rates in hot summer temperatures.[1] In the U.S. isolates have been recovered in Alabama,[9] Georgia,[10] Maryland,[11] Mississippi,[9] North Carolina,[2][10] Tennessee,[10] and Virginia.[10] Samples have also been isolated in Italy,[4] Spain,[5] and Mexico.[7]

• Phytophthora Database
• MycoBank