Industry is taking a number of steps to help eliminate the disease from crops in Victoria in advance of the 2015 growing season. These include the development of more sensitive seed-testing protocols to ensure clean seed is used for planting, developing improved fungicide treatments for seed, adopting planting practices that involve crop rotation and selecting sites that are less conducive to disease development.
Until relatively recently, downy mildew on all Papaver species were assumed to be the single species, Peronospora arborescens. With the advent of molecular taxonomy, the species has been revisited and a recent paper by Voglmayr et al. (2014) describes two species infecting Papaver somniferum (Peronospora meconopsidis and P. somniferi).
Peronospora somniferi causes discoloured blotches on the upper leaf surface (pale green to purple brown) with grey-purple mould-like growth on the lower surface of Papaver somniferum leaves, corresponding to the blotches on the upper surface. Severely affected leaves are shrivelled and brown, and the plants are stunted.