Initial leaf symptoms of Alternaria blight of carnation, caused by the fungus are tiny purple dots. When moist weather prevails, the spots enlarge, developing into large lesions with a purple margin and a yellow-green border surrounding a grey-brown centre covered with black spores. Several lesions may expand and coalesce to form large, irregular necrotic areas that eventually kill the entire leaf. The branches are most frequently infected at the nodes and branch base. These infection centres enlarge to form cankers, which eventually girdle the stem, causing the branch to wilt and the girdled portion turn to yellow and die.
How Alternaria blight disease causes damage in carnation?
