Inhibitory Effect of Azadirachta Indica A. Juss and Eucalyptus Camaldulensis Extracts on the Growth of Alternaria Alternate that Causes Palm Leaf Spot Disease

Abstract

A laboratory study was conducted to evaluate the efficacy of water, alcohol and oil extracts of two types of plants, Azadirachta indica A. Juss and Eucalyptus camaldulensis, with three concentrations (10, 20 and 30)% of each extract against the fungus Alternaria alternate that causes date palm leaf spot disease. The laboratory results showed that the oily extract of the seeds of A. indica gave the highest percentage of radial growth inhibition of the pathogenic fungus, which was 71.1, 75.3 and 77.5 at concentrations of 10, 20 and 30%, respectively, followed by the oil extract of E. camaldulensis leaves in the second place, which gave the percentage of Inhibition reached 55.1, 59.8 and 62.7%, respectively, at the same mentioned concentrations, As for the effect of extracts on the severity of palm leaf infestation with the pathogenic fungus, we note the superiority of A. indica seed oil extract in reducing infection severity, which amounted to 42.1, 38.8 and 23.6% at concentrations 10, 20 and 30%, respectively, followed by the oil extract of E. camaldulensis leaves in the rank. The second, which reduced the infection rate to 52.2, 46.5 and 42.1%, respectively, at the same concentrations, compared to the control treatments, in which the severity of infection reached 83.6 and 82.8%. It is worth noting that all plant extracts and their tested concentrations significantly reduced the severity of palm leaf spot disease compared to the control treatment.