Occurrence and Control of Strawberry Powdery Mildew in Al-Shoubak/ Jordan

Powdery mildew of strawberry caused by the fungus Sphaerotheca macularis f. sp. fragariae was found in Al- Shoubak area under glasshouse conditions. White superficial fungal growth was more abundant on the lower than the upper leaf surface and no cleistothecia were noticed on any plant parts. Top leaves were more susceptible than middle or bottom leaves. Strawberry cultivars Albion and Camarosa were artificially inoculated with the fungus under growth room conditions. Disease incidence and severity were 46.7% and 50.8% in cv. Albion and significantly different from that (1.6% and 5.2%, respectively) in cv. Camarosa. In vitro leaflet bioassays and a runner-tip plantlet experiment were done to assess the influence of some fungicides and resistance-inducing chemicals in controlling the disease. Canvil was significantly effective in controlling the disease while sulfur, Triadimefon, Mycozim and Punch were only effective at the high application rates. Both calcium chloride at 1 g/l and hydrogen peroxide at 10 mM were effective in controlling powdery mildew on strawberry.