Molecular identification of Peronospora viciae causing downy mildew on field pea pods and its management

Abstract

In the growing season 2016–2017, downy mildew disease was initially occurred on pea pods followed by plantlets leaves that observed in different locations where pea plants were grown at Kafr-El-Dawar district, Beheria governorate, Egypt. This irregular observation leads to thought that the cause of disease is new to this particular region. Molecular identification of the isolated fungus proved that the causal agent is Peronospora viciae. The sequences of the fungal isolate sent to GenBank and registered under accession number MN620384. Under field trials, it was observed that throughout the two cultivated seasons the fungicides application had greater effect on downy mildew incidence comparing with applied chemical inducers. Along the two cultivation seasons, pea plants sprayed with salicylic acid, potassium sorbate and ascorbic acid highly suppressed the disease incidence between 12.4 and 17.1%. Moderate effect was recorded as 19.2–22.7% disease reduction with potassium bicarbonate, lemongrass oil, lemongrass oil and humic acid application. The lowest effect was recorded as 32.5% at sodium benzoate treatment; meanwhile, 54.3% disease incidence was recorded at untreated control.

Under field conditions, significant reduction in pea downy mildew disease was achieved by the use of fungicide alternative as foliar application. Therefore, these approaches could be utilized successfully for controlling this foliar disease especially they distinguished with safely use and avoidance of environmental pollution.