Evaluation of Cyclone for the management of powdery mildew in cut gerbera

Project Code BPR14-071

Project lead

Janice Elmhirst  Elmhirst Diagnostics and Research, British Columbia, Canada

Objective

To evaluate efficacy of Cyclone for the management of powdery mildew in cut gerbera

Summary of Results

Background

Powdery mildew, caused by Erysiphe species or Podosphaera species is one of the most important diseases in ornamental crops in Canada. The disease in cut gerbera was identified as a priority issue by growers at the 2013 Canadian Biopesticides Priority Setting Workshop, and the Pest Management Centre’s Pesticide Risk Reduction Program was tasked to identify a promising reduced-risk product for the management of this disease.

In a screening trial BPR14-070 conducted in 2014, the product Cyclone was identified as a promising product for the management of powdery mildew in greenhouse cut gerbera; however further validation of its efficacy in gerbera plants was needed. In 2015, therefore, two efficacy trials were conducted in British Columbia with the intention that data from these efficacy trials could be used to support an User Requested Minor Use Label Expansion (URMULE) of Cyclone for the management of powdery mildew in greenhouse gerbera.

Approaches

Cyclone was evaluated at three rates (1.2%, 1.6% and 2.0%) combined with 0.25% Liberate as the surfactant, and these treatments were compared to the commercial standard Nova at 0.034%. Each treatment had 4 replicates and applied 4 times at a weekly interval during the trials. Incidence of diseased leaves, mean number of powdery mildew lesions per plant, and disease severity (mean percentage of leaf area with mildew per plant) were assessed to estimate efficacy of each treatment.

Results

Overall, in two trials with three rates, all showed significant control/suppression of powdery mildew disease compared to the untreated controls when assessed according to each of three disease assessment indices. The highest rate (2%) showed the best control of powdery mildew during the course of the two trials, compared with the other two rates, reducing the incidence of diseased leaves by 17-90%, reducing the mean number of powdery mildew lesions per plant by 40-98%, and the disease severity by 41-92%. The middle rate (1.6%) showed similar, although numerically lower efficacy levels to those achieved with 2%. The 1.2% rate significantly suppressed the disease in two trials based on the three assessment indexes, but in general the efficacy levels appeared lower than those provided by other two rates in most assessment dates. All three rates were able to maintain significant suppression of the disease until harvest.

The two Cyclone efficacy trials confirmed the efficacy shown in the screening trial in 2014. The data generated with Cyclone in these trials will be used to support an URMULE request for registration of Cyclone for the control of powdery mildew in greenhouse gerbera.

 

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