Allium sativum Extract as a Biopesticide Affecting Pepper Blight

Abstract

The use of inhibitory biological substances contained in garlic (Allium sativum L.) was explored in this study as a possible biopesticide for controlling Phytophthora capsici Leonian. The advantages of garlic extract are that it is not persistent in the soil, it is easily degradable, and it is nontoxic to humans and domestic animals. Total inhibition of mycelial growth of P. capsici was observed at a concentration of 150 mg·mL−1 of garlic extract. The morphology of mycelia treated with the garlic extract at a concentration of 100 mg·mL−1 was abnormal under the microscope, with mycelia slowly swelling and bioplasm accumulating. Garlic extract exhibited strong inhibitory effects against zoospore germination of P. capsici at 75 and 50 mg·mL−1, where the inhibition rate was over 97.13%. The extract also inhibited zoospore germination with a concentration as low as 37.5 mg·mL−1. The results indicated that the effective concentration (EC50) values of garlic extract against mycelium growth and zoospore germination were 64.2 and 25.9 mg·mL−1, respectively. The minimal inhibitory concentration (MIC) and minimal antimicrobial concentration (MAC) of garlic extract were 100 and 150 mg·mL−1, respectively. In a pot trial, garlic extract had a protective effect on pepper blight.