Potential use of Apis mellifera L. honey in the management of the cucurbit powdery mildew caused by Podosphaera xanthii (Castagne) under greenhouse conditions.

Powdery mildew by Podosphaera xanthii (Castagne) is a major disease of greenhouse cucurbitaceous crops worldwide. Honey by honeybees has been reported as an antimicrobial for diseases in humans, animals, and plants. The aim of this study was to assess Apis mellifera honey against P. xanthii in cucumber plants. During nine consecutive weeks, four different honey concentrations (2.0%, 2.5%, 3.0% and 3.5%), a chemical control (Azoxystrobin) and an untreated check (water) were evaluated. Except for honey at 2%, every concentration was significantly different from the untreated check. Honey concentrations at 3% and 3.5% were found to be the most effective, and their area under disease progress curve (AUDP) was statistically comparable to that of Azoxystrobin with 1048.3, 642.3 and 575.8 AUDP, representing 72.4%, 83.1% and 84.8% of efficiency compared to the untreated check, respectively. These results provide preliminary information on the potential use of honey in managing strategies of the disease under greenhouse conditions.