Look at other Pythium genomes, like P. ultimum (NCBI has 3 assemblies). http://www.ncbi.nlm.nih.gov/assembly/?term=Pythium
Mycocosm (http://genome.jgi-psf.org/programs/fungi/index.jsf) has some oomycetes genomes too. Take a look there, I think it work for estimates. But just a sequencing and assembly will answer your question!