The tomato powdery mildew in Australia is a new species of powdery mildew never reported before on tomatoes. It develops characteristic spider-like lesions on the surface of the leaves. The identify and source of the tomato powdery mildew is not known. The only fungicide registered for the control of powdery mildew on tomatoes in Victoria is Lime-Sulphur. But many growers have found that sulphur does not work and that their crops still become severely damaged. A preliminary study was thus conducted to determine the identity, source and basic epidemiology of the pathogen infecting processing tomato crops.