Host range of a powdery mildew (Erysiphe orontii) on tomato

A powdery mildew disease of greenhouse tomato first appeared in the Fraser Valley of British Columbia in 1995. Thee causal agent was identified as Ery siphe orontii. Host range studies were conducted using uniform levels of in oculum of the pathogen under greenhouse conditions.. Of 26 tomato cultivars inoculated, cv. DRW4409F1 had the least powdery mildew infection. Twenty-f ive of the 26 tomato cultivars tested, as well as eggplant cv. Early Long P urple, nightshade and tomatillo, were susceptible to E. orontii. Tobacco an d potato (cv. Epicure) had slight infection. Cultivars of pepper, potato, c orn, strawberry, raspberry, bean, feverfew, borage, delphinum, petunia, imp atiens, gazania, morning glory, zinnia, african daisy, cosmos, wild buckwhe at, curled dock, and knotweed were not susceptible to E. orontii. This stud y indicates that resistance to powdery mildew of tomato is available and sh ould be explored in breeding programs to develop powdery mildew-resistant c ultivars for the greenhouse industry.