Neem (Azadirachta indica a. Juss) components: Candidates for the control of Crinipellis perniciosa and Phytophthora ssp.

Abstract

Witches' broom and pod rot are the two most devastating diseases of cocoa in South America and Africa, respectively. Their control by means of phytosanitation and chemical fungicides is labor-intensive, costly and, in many cases, environmentally undesirable. Therefore efforts are made in order to identify alternative, environmentally safe and cost-efficient methods for the control of these pathogens. Promising candidates are components of the neem tree (Azadirachta indica), that have been used for centuries in Asia as insecticides, fungicides, anticonceptionals in popular medicine. Here we report about tests on the effect of various concentrations of extracts from neem leaves on growth of mycelia of Crinipellis and Phytophthora and on germination of spores of Crinipellis. We show a 35% growth reduction of mycelia of Phytophthora on neem leaf extract media, whereas growth of mycelia of Crinipellis was not affected, even at the highest concentration of neem leaf extracts used (35%). However, the most dramatic effect of neem leaf extracts is observed on Crinipellis spore germination, here the extracts (20-35%) reduced germination almost completely. Based on these results, we believe that the neem tree might be a source for the production, on small and medium scale, of an effective and cheap formulation for the control of Crinipellis and Phytophthora.

Potential Use of Medicinal Plants as Biological Crop Protection Agents

“…Juss.) has been used to control cancer cells, pests, fungi, bacteria and nematodes [70][71][72][73][74][75][76][77][78][79]. Recently, in a study completed by de Freitas Silva et al [80] more than 30 medicinal plant's volatiles such as Cymbopogon nardus and Dysphania ambrosioides applied against the root-knot nematode.…”