Yellow rust—Phragmidium rubi-idaei
Yellow rust occurs mostly on boysenberries and blackberries. Small, yellow, blisterlike pustules appear
in spring, first on fruiting canes and then on leaves. Canes dry out and crack, preventing proper ripening
of fruit.
Solutions
The fungus that causes yellow rust overwinters on fruiting canes. Prune out and destroy diseased canes
before fall rains and apply a fixed copper fungicide. Yellow rust spores are released from leaves and
spread by wind in spring. Avoid overhead irrigation. Spray with a fixed copper
fungicide in spring when
new laterals are leafing out, and again when flowers begin to open. | 
Yellow
rust on raspberry leaves
|
