Basil Tree, a New Host of Downy Mildew Pathogen Peronospora belbahrii

                

1Gyeonggido Agricultural Research and Extension Services, Hwaseong 18388, Korea
2Department of Biology, Kunsan National University, Gunsan 54150, Korea
3Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Korea

Abstract

Basil (Ocimum spp.) is a popular herb grown worldwide. During the past fifteen years, a downy mildew pathogen has caused considerable damage to basil cultivations. In August 2017, downy mildew disease symptoms were found on Basil Tree (or long foot Basil Tree), which was developed by the grafting of two basil varieties and is a continuous harvest plant with a woody trunk. The present study reports the occurrence of downy mildew disease in basil Tree and identifies the causal pathogen, as Peronospora belbahrii.

Figures & Tables

Fig. 1. Downy mildew disease caused by on basil tree. A, downy mildew occurred in a plastic house containing numerous basil tree pots; B, early symptom of yellowish, or yellow-green, leaves; C, late symptom of the leaves covered with greyish to brown conidia and often defoliation; D, yellowing and brownish spots on upper leaf surfaces; E, whitish conidiophores and greyish conidia on corresponding lower surfaces; F, conidiophore; G, ultimate branchlets; H, I, conidia (scale bars: F = 100 μm, G, H = 10 μm)