Studies on leaf and nut blight of cashew (Anacardium occidentale) caused by Cryptosporiopsis sp. in Tanzania

Abstract

Leaf and nut blight (Cryptosporiopsis sp.) of cashew is a very common and destructive disease in Tanzania. Symptoms coincide with flushing of shoots and flowering from July to December. Cashew leaf and nut blight infects young tender shoots, pseudo-fruits and nuts. Initially, the disease appears in the form of small, scattered brown spots on the leaf lamina. Later, these spots increase in size and coalesce covering larger leaf area, with dark brown margin. The first symptoms of the disease are chlorotic spots on both sides of the youngest tender leaves. Leaf spots vary in size, shape and colour between different varieties of cashew. The spots are brown, with a dark brown border, spreading necrotic lesions leading to leaf blight; circular, irregular or angular 1–2 cm in diameter; irregular roughened or corky lesions with eruption and necrosis of epidermal tissue, sometimes localized along veins. The diseased leaves curl and can be totally defoliated.