Managing blueberry rust under an evergreen system

M. Simpson, P. Wilk, D. Collins, D. Robertson, R. Daniel
Blueberry rust caused by the fungus Thekopsora minima, is a significant disease of evergreen blueberry production in Australia. Severe rust infections can cause defoliation, and reduce fruit set in the following season. Management of blueberry rust relies largely on a small number of chemicals, placing selection pressure on the pathogen. A randomized complete block design trial was conducted on a commercial orchard to evaluate the efficacy of six fungicides from four chemical activity groups. Commercial fungicide formulations containing azoxystrobin, azoxstrobin+ cyproconazole, dithianon, fenbuconazole, tebuconazole and mancozeb were applied to foliage every 14 days over a 12-week period. Disease severity was assessed fortnightly based on the percentage of leaf area showing rust symptoms. All chemicals tested significantly reduced blueberry rust incidence when compared with the untreated control. Fenbuconazole and tebuconazole were more effective than mancozeb, which is typically used across the industry for rust control. Fenbuconzaole and tebuconazole were most effective at reducing incidence of blueberry rust, followed by the Quinone outside Inhibitor + DMI combination azoxystrobin + cyproconazole, and azoxystrobin on its own. These chemicals could be recommended for control of blueberry rust in rotation with currently permitted chemicals to expand the number of available management options for growers.
Simpson, M., Wilk, P., Collins, D., Robertson, D. and Daniel, R. (2017). Managing blueberry rust under an evergreen system. Acta Hortic. 1180, 105-110
DOI: 10.17660/ActaHortic.2017.1180.14
Thekospora, Pucciniastrum, Naohidemyces, Vaccinium, fungicide

Acta Horticulturae