Microscopic

P. pluvialis hyphal swellings in water

P. pluvialis hyphal swellings on agar

Oogonium and oospore with amphigynous antheridium

Oogonium and oospore with amphigynous antheridium

Sporangia showing typical ovoid shape and semi-papillate condition

Sporangium showing typical ovoid shape and semi-papillate condition

P. megakarya sporangia

 Catenulate, globose to subglobose hyphal swellings, some of them with radiating hyphae scale bar = 50 μm.

 Aplerotic oogonia of P. arenaria with paragynous antheridia. Scale bar = 20 μm

Globose papillate sporangia of Phytophthora arenaria on V8 agar flooded with soil extract. (Scale bar = 20 μm)