<i>In vitro</i> and <i>in vivo</i> effect of Mancozeb 80 WP on development of <i>Pestalotia heterocornis</i> agent of leaf blight of Cashew in Far North Cameroon

Abstract

Objective: Cashew cultivation in Cameroon is facing enormous constraints, including fungal diseases. Among these diseases, pestalotia leaf blight occupies an important place in terms of damage in field but no strategy management is available in Cameroon. The aim of the present study is to characterize and evaluate the effects Mancozeb (Mz) fungicide on the development of Pestalotia heterocornis, the causative agent of pestalotia leaf blight both in vitro and in vivo.

Methodology and results: Isolates of P. heterocornis were obtained from diseased cashew leaves collected in the field. Different morphotypes of spores were observed under an optical microscope and their biometric parameters were then measured. Growth diameter and pathogenicity test were performed. The Mancozeb concentrations C1 = 500μg /ml, C2 = 50μg / ml and C3 = 5μg /ml were used to compare their effect on the growth and germination of spores of isolates. Several spore morphotypes were identified. The percent inhibition of growth with resistant isolate was 100% and that of the most sensitive was 69.68% at dose C1. Mancozeb completely inhibited (100%) the germination of conidia of P heterocornis at all concentrations tested. In vivo, the highest concentration (500μg /ml) of Mancozeb reduced development of disease on plant tested.

Conclusion and application of findings: Mancozeb 80WP reduced the development of P. heterocornis in vivo and vitro. Mancozeb at the concentration of 500μg /ml can be adopted by the farmers to protect cashew trees against Pestalotia heterocornis in nursery.