The severity of an infection is depending on the: A weak infection could be completed and a moderate infection could be nearly completed, where the leaf wetness was not lasting long enough to complete a severe Infection. The graph below shows an infection for the 7th and 8th of March for Sabukia Kenya. The Coffee Leaf Rust Infection Model shows the progress of weak, moderate and severe Infections. Air Temperature in between 15☌ and 28☌. ![]() At least after 22 to 24 hours the infection process is finished. Appressoria formation takes less than 6 hours under optimum condition. Germination takes place within 2 to 10 hours depending on climate conditions. Uredospores need free water to germinate and to form an appressoria. Symptoms are visible 2 t0 3 weeks after infection. The centers of older lesions become necrotic and the sporulating zone is restricted to the outermost zone.Ī major effect of the rust is to cause defoliation. Young lesions may appear as small chlorotic spots before sporulation occurs. ![]() Initially, these are only 2-3 mm in diameter, but steadily expand and can eventually reach a diameter of several centimeters. Yellow to orange powdery spots appear on the underside of leaves, with corresponding chlorotic patches on the upper side. In 1869 it was found in Sri Lanka (former Ceylon), where it spread over the whole coffee growing areas worldwide, except the growing areas of Hawaii. It was first detected in 1861 in the lake Victoria Area of Kenya. Coffee Leaf Rust caused by Hemelia vastatrix is the most well known coffee disease.
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