ISSN 2384-5058
Corresponding author: Falade MJ . :Received: 04.05.2022 | Accepted: 06.05.2022 | Published:11/05/2022
ABSTRACT
Cashew leaf spot caused by Pestalotia heterocornnis is responsible for reduction in yield or productivity of cashew with serious economic implications. Based on the above, laboratory studies were conducted to evaluate the effect of hot water leaf extract of Coat button (Tridax procubens Linn), Iron weed (Sida acuta Burm.f) and Castor oil leaf (Ricinus communis Linn) in the management of the disease. Four concentrations of the extracts (10, 20, 30 and 40%) were prepared and applied in-situ to determine their efficacy of control on pestalotia leaf spot disease of cashew. The result of the studies shows statistically significant (p < 0.05) variation in P. heterocornnis growth depending on the extracts and concentration. T. procumbens at 40% concentration was the most effective in reducing the growth of the fungus and this was closely followed by R. communis and S. acuta was the least. Growth rate induced by T. procumbens at 40% concentration was 2.81 mmday-1 while that of R. communis and S. acuta were 2.91 and 3.10 mmday-1 respectively. All the extracts do not have effect on sporulation but reduced conidia germination. There was 61-87% inhibition of conidia germination irrespective of plant extracts and concentration. The study concluded that the active compounds in the leaf extracts can be developed into synthetic fungicide for the management of leaf spot disease of cashew.
Keywords: Cashew, Plant extracts, Inhibition, Pestalotia heterocornnis