Efficiency of the Extracts of Some Plants on Squash Powdery Mildew

Experiments were conducted under laboratory, greenhouse and field conditions to investigate the possible utilization of plant extracts to control Sphaerotheca fuliginea, the causal pathogen of squash powdery mildew. Six air dried plant materials, i.e. anise seeds, blue gum leaves, chamomile flowers, cumin seeds, marjoram herb and thyme herb, as well as three organic solvents (acetone, methanol, and petroleum ether) were used for extraction. Methanolic extracts (ME) of blue gum and thyme gave significant decrease in spore germination of S. fuliginea. Treating detached leaves with the organic solvents extracts (OSE) as preventive and curative treatments proved that the first was more effective than the second in controlling the disease. Spraying with (ME) of blue gum and thyme decreased powdery mildew disease incidence and increased total phenols. Also, spraying squash in greenhouse and field with the (OSE) as preventive and curative treatments gave sufficient control to the disease in most cases. However, the efficiency of the methanolic extract of thyme herb in controlling the disease as curative treatment was always comparable to that of the fungicide Afugan. DOI: 10.5901/mjss.2013.v4n11p3