New Virulent race of Plasmopara helianthi attacking sunflower in the United States
Professor W.E. Sackston of the Macdonald University (Ste Anne de Bellevue, Quebec, Canada) has informed the French Plant Protection Service of the appearance of a new virulent race of Plasmopara helianthi.
This race has been recorded in 1980 at Brooking (South Dakota) and at Breckenridge (Minnesota) where it attacked all hybrids and lines known to have Pl1• Pl2 or Pl4 genes.
It is not yet known how widely this new race may be distributed.
In France, measures are taken to secure fungicide treatments of sunflower seeds.
Sources
Plant Protection Service, Paris