Screening of Potential Plant Extracts for Biological Control of Potato Late Blight (Phytopthora infestans) using Detached Leaf Assay and Whole Plant Systems.

Abstract

The study aimed to evaluate the effect of four selected plant extracts (sunflower, ginger, sugarbeet and malunggay) against Phytophthora infestans causing late blight of potato using detached leaf assay and whole plant testing systems. In detached leaf assay, all plant extracts reduced the late blight infection compared to the untreated control 48 hours after inoculation. The highest percentage control was recorded in ginger extract followed by malunggay, sugarbeet and sunflower extracts with 70.44%, 51.78% and 44.44%, respectively. However, the efficacy of the extracts declined considerably after 72 hours. In the whole plant systems, the highest percentage local protection was noted in the standard fungicide, followed by malunggay, ginger and sugarbeet and sunflower extracts a week after inoculation. Reduction of the effectiveness of the plant extracts was also observed after two weeks. In terms of yield, plants sprayed with malunggay extract gave the highest yield increase over the control followed by Mancozeb, sunflower and ginger extracts. These results showed the potential of the above mentioned plant extracts in the management of potato late blight.