Entomosporium Leaf Spot Control on Red-tip Photinia in the Landscape

Abstract

Abstract In 2006, 2007, and 2008, efficacy of the soil-applied fungicide drench All-In-One Rose & Flower Care [All-In-One] (tebuconazole) was compared with the foliar-applied fungicides Daconil Weather Stik (chlorothalonil), Immunox Multipurpose Fungicide (myclobutanil), RosePride Disease Control Concentrate (triforine), and Disease Control for Roses, Flowers & Shrub Concentrate (tebuconazole) for the control of Entomosporium leaf spot on field-grown red-tip photinia (Photinia × fraseri ‘Birmingham’). While the label rate of All-In-One drench was poured over the soil surface around the base of each plant at monthly intervals, the foliar applied-fungicides were applied at label rates at 2-week intervals to runoff. Over the study period, drenches of All-In-One failed to protect photinia from Entomosporium leaf spot, while the foliar-applied fungicides significantly reduced disease levels. Defoliation on the non-fungicide treated controls was similar to the All-In-One drench and ranged over the study period from 25 to nearly 75%. In contrast, little if any leaf spotting and no defoliation occurred in any of the study years on the photinia treated with Daconil Weather Stik, Immunox Multi-purpose Fungicide, RosePride Disease Control Concentrate, and Disease Control for Roses, Flowers & Shrub Concentrate. Poor efficacy of the All-In-One was attributed to an inadequate concentration of the fungicide component tebuconazole when applied at the label drench rate.