Activity of seaweed and cyanobacteria water extracts against Podosphaera xanthii on zucchini

Abstract

The purpose of this research was to study the effects of water extracts of algae belonging to the phylum Rodophyta, Heterokontophya, Chlorophyta and of Cyanobacteria against Podosphaera xanthii on zucchini (Cucurbita pepo) cotyledons. Each extract was sprayed on the upper surface of cotyledons at the concentration of 0.5 %, then cotyledons were inoculated with six 10-µl drops of a spore suspension of the pathogen (1×106 spores/ml), and incubated on water agar in Petri dishes. Depending on the species, the extracts showed inhibition, stimulation or no effect on the disease severity caused by P. xanthii and on the pathogen sporulation density. Extracts of Corallina sp., Halopithys sp., Sargassum sp. and Anabaena sp. showed significant inhibitory effect on both parameters. This study suggests that seaweed and cyanobacteria water extracts applied on zucchini cotyledons may be considered in further experiments on plants as a useful preventative tool for the disease management in sustainable agriculture.