Viburnum Disease Management During Propagation

Viburnum species are among the top-selling ornamental shrubs in Central Florida for placement in landscapes. Nurseries propagate viburnum by using landscape or production stock plants that may appear healthy but often harbor several foliar diseases prevalent in nurseries and landscape environments. These diseases then compromise production during the propagation stage. Research was conducted to determine if either drenching or dip-applying fungicides at the beginning of propagation would minimize disease severity. Two experiments using five treatments of fungicides were screened for efficacy. The pathogens Colletotrichum sp., Cercospora sp., Corynespora sp., and Phyllosticta sp. were isolated during the experiment. As a drench, both PostivaTM and Orkestra® significantly reduced final disease severity by > 50% compared to the untreated water control. For the dip-applied fungicide treatments, PostivaTM, Orkestra®, Ryora®, and Omega® all significantly reduced final disease severity by 57% on average compared to the control. The same four treatments also prevented disease severity from increasing in a statistically significant manner over time, unlike the control. Root length, fresh and dry weight were only negatively impacted by Ryora® as a drench.