Seed as a pathway has been established and accepted.
Yes
Blotter incubation, ELISA, PCR
It is difficult to detect P. halstedii from sunflower seeds and the commercial usefulness of the tests has not yet been proved. Testing methods have not been standardized or validated.
CABI CPC
chemical
Resistant varieties for various races exist. Seed treatments with meta-laxyl and mefenoxam (FRAC 4 fungicides) have been effective.
Doken MT, 1989. Plasmopara halstedii (Farl.) Berl. et de Toni in sunflower seeds and the role of infected seeds in producing plants with systemic symptoms. Journal of Phytopathology, 124:23-26
MartÃnez, A.L., Quiroz, F.J. and Carrera, A.D., 2021. Detection of Plasmopara halstedii in sunflower seeds: A case study using molecular testing. Journal of the Saudi Society of Agricultural Sciences, 20(6), pp.395-400.
Nishimura, M., 1922. Studies in Plasmopara halstedii. Journal of the College of Agriculture, Hokkaido Imperial University, Sapporo, Japan, 11(3), pp.185-210.