It is an obligate parasite and the causal agent of the downy mildew of the plant model organism Arabidopsis thaliana.

Like the other Hyaloperonospora species, H. arabidopsidis is highly specialized to Arabidopsis thaliana.

[2] Pel, Michiel J. C.; Wintermans, Paul C. A.; Cabral, Adriana; Robroek, Bjorn J. M.; Seidl, Michael F.; Bautor, Jaqueline; Parker, Jane E.; Van den Ackerveken, Guido; Pieterse, Corné M. J.; Vinatzer, Boris A.

"Functional Analysis of Hyaloperonospora arabidopsidis RXLR Effectors".

Marco, Francisco; Buso, Enrique; Carrasco, Pedro (2014).