Diseases of Fruit Plantation Medicinal and Aromatic Crops

Leaf blight disease

Causal organism – Dendrophoma obscurans

Symptoms

• The disease is most prominent on the leaves, although at times it appears on the calyx. Usually the spots on the single leaflet are limited to one to five or six.
• The initial young spots are uniformly reddish purple and almost circular in outline., The spots near one of the main veins are elliptical.
• Later three zones viz., normal green of the leaf, a light brown zone about 5 mm width, and, finally, a dark brown central area 2 to 3 mm in diameter are formed.
• The white central area characteristic of leaf spot is never present.
• The spots appearing on a prominent vein, and especially if on the midrib, the typical V-shaped lesion is formed, with the purple coloured tissue extending in a fanlike manner to the border of the leaflet.

Management

• Spray the crop with 1 % of mercuric acetate solution