Abstract

Attempts were made at Bole, Ghana to determine the incidence and severity of leaf spot of Vitellaria paradoxa (shea), identify the causal pathogen and alternative hosts, and assess the impact of disease incidence on shea nut yield. Each of 4960 shea trees and surrounding herbs, shrubs or trees were inspected for symptoms of leaf spots. Disease severity was scored on a scale of 0 to 4 on each of 30 leaves randomly sampled from the lower, middle and upper canopy of each of 64 selected trees categorised into eight different classes on the basis of age and leaf characteristics. Out of the 4960 V. paradoxa plants inspected, 2976 (60%) was infected with the disease.  A range of fungi was isolated from the infected leaves but only Pestalotia spp. was found to be the causal pathogen of leaf spot of V. paradoxa.  Nauclea latifolia Smith, a Rubiaceae and Daniellia oliveriHutch and Dalz, a Caesalpiniaceae were found to be alternative hosts.  The disease was most severe in the lower portion of the canopy and it adversely affected yield. This is the first report of Pestalotia leaf spot disease on N. latifoliaand D. oliveri.

Key words: Vitellaria paradoxa, alternative hosts, leaf spot, Nauclea latifolia,Daniellia oliveri.