Evaluation of some biocontrol agents to control Thompson seedless grapevine powdery mildew disease

Abstract

Abstract This investigation aimed to evaluate the effect of some biocontrol agents against the powdery mildew of Thompson seedless grapevines. The study was carried out during the two successive seasons (2016 and 2017) at a private organic vineyard orchard located at El Beheira Governorate, Egypt. Uncinula necator (syn. Erysiphe necator) is a fungus that causes powdery mildew of grapevine. It causes severe loss in yield quantity and quality. Application of different biocontrol agents, e.g., Trichoderma harzianum, T. hamatum, T. viride, and their combinations, as well as the Blight stop (Trichoderma spp.), a commercial biocide and micronic sulfur, was an attempt to control the disease. The mixture of the three Trichoderma spp. showed the highest efficacy (80.16 and 89.95%) of controlling the disease incidence and severity in the two seasons 2016 and 2017, respectively, followed by the treatment of Blight stop + micronic sulfur (77.12 and 84.02%), while micronic sulfur showed the lowest effect (57.02 and 41.32%). At all treatments, the yield was increased and the chemical characteristics, e.g., “total sugars, total soluble solids (TSS), total anthocyanin (% in mg/100 g F.W.), and total phenols (mg/g betties as gallic acid equivalent)” of berries were improved. On the contrary, the percentage of total acidity was decreased at all treatments than in the control.

Keywords

• Grapevine
• Uncinula necator
• Powdery mildew
• Micronic sulfur
• Biocontrol agents