coffee leaf rust | Hemileia vastatrix | Full explanation

coffee leaf rust | Hemileia vastatrix | Full explanation of coffee leaf rust

This is most destructive disease of coffee. It attacks all species of coffee but is most severe on coffee arabica.
SYMPTOMS
Orange yellow powdery spots on the lower side of leaves. The centre’s of the spot eventually become dry and turn brownish, leaves fall off prematurely. Repeated infections result in the death of the trees.

The fungus Hemileia vastatrix, exists primarily as mycelium, uredia and uredospores in infected leaves. They infect continuously. The fungus occasionally produces teliospores which on germination form basidiospores (donot infect coffee). There is no alternate host of this fungus. Uredospores are spread easily by wind , rain and perhaps by insects. Spores germinate only in the presence of free water and enter leaves through the stomata of leaves. The mycelium grows between the leaf cells and sends haustoria into the cell. New uredia may appear in the lower side of leaf within 10 to 25 days from infection.The premature shedding of leaves weakens the trees and results in reduced yields , severe dieback of twigs and death of trees.

Control measures of coffee rust

1) copper fungicides
2) sufficient tree pruning
3) good site selection
4) use of resistant varieties.