English

D M S Menge,E O Monda,P O Okemo,M Makobe

doi:10.5897/ajps12.033

Abstract

Rust (Uromyces appendiculatus) is a major foliar disease that reduces yield and pod quality in beans. The field trial of French beans was established at Jomo Kenyatta University of Agriculture and Technology (JKUAT). Single plant extracts and combinations of Boscia angustifolia, Zanthoxylum chalybeum and Melea volkensii were used to evaluate their effect on U. appendiculatus in the field. During the growing period, beans were infected with rust from natural inoculum at the field. Physiological responses such as carbon dioxide assimilation, transpiration (E), stomatal conductance (gs), and photosynthetic rate (Pn) of French beans treatments were examined after extracts of three antifungal plants were sprayed. B. angustifolia - Z. chalybeum combination and single plant treatment M. volkensii had positive effects on enhancing the rate of photosynthesis in bean plants. The high regressions between stomatal conductance and rate of transpiration in the treatments indicated that stomatal conductance and rate of transpiration were interdependent and it was interpreted to mean that stomatal conductance enhanced rate of transpiration at different times of the day. These plant extracts however caused an increase in the rate of transpiration of the bean plants, which resulted in loss of water. Results reveal bioactive potential of the flora from M. volkensii and a combination of B. angustifolia and Z. chalybeum to produce metabolites with potential applications as botanical pesticides.   Key words: Antifungal, beans, physiological responses, rust.

Highlights

IntroductionThe importance of the French beans is due to their high nutritive value in both energy and protein contents
The importance of the French beans is due to their high nutritive value in both energy and protein contents.increasing the crop production is one of the most important targets of agricultural policy in several countries.The bean rust fungus (Uromyces appendiculatus) is of worldwide importance as a yieldreducing disease of Phaseolus vulgaris L., potentially cause yield losses up to 50% (Venette and Jones, 1982; Berger et al, 1995; De Jesus Junior et al, 2001)
French bean variety Amy seeds were planted in 4 × 3 m plots each separated by a 1 m path between the treatments and the replications

Summary

Introduction

The importance of the French beans is due to their high nutritive value in both energy and protein contents. The bean rust fungus (Uromyces appendiculatus) is of worldwide importance as a yieldreducing disease of Phaseolus vulgaris L., potentially cause yield losses up to 50% (Venette and Jones, 1982; Berger et al, 1995; De Jesus Junior et al, 2001). Under severe disease, it completely defoliates the plant and can cause 100% crop failure (Steadman et al, 2002). Studies have shown that some plant species have antifungal compounds (Fabry et al, 1996; Okemo et al, 2003)

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