What Conditions Help Spread the Disease?
Rain and moderate to warm temperatures (18 degrees Celsius) lead to spore dispersal.
What Are the Symptoms?
Leaf tissues turn orange-brown to reddish-brown, starting from the edges of the leaf, moving inward towards the base of the leaf. Leaf veins and petiole remain a bright green colour. All leaves on a branch may be affected. Discolouration deepens to a bronzy, reddish-brown colour as the season progresses.
Infected leaves will often remain attached to the tree over the course of the winter (they do not fall off). Branches may dieback as the disease progresses systemically. Leaves that overwinter may have a pebbly surface texture (like the surface of a curling rink), reflecting the development of spore-producing structures (perithecia).