Irrigation Frequency and Volume has Little Influence on Phytophthora Root Rot in Container-grown Rhododendron

Abstract We evaluated whether reducing irrigation frequency and volume alters the ability of Phytophthora plurivora P. cinnamomi to cause root rot on rhododendron grown in a noninfested potting medium or media infested with 1 100 propagules per gram (ppg) pathogen. Plants were irrigated maintain substrate moisture >70% container capacity (1.0X), one-half 1.0X (0.5X), two times at each event for one week, followed by no irrigation, until soil reached <50% capacity. Aboveground disease symptoms (chlorosis, stomatal conductance, wilting, plant death) weekly rot, pathogen presence, biomass, nutrient uptake measured end trial. Both pathogens generally caused mild ppg severe ppg. Reducing did little lessen either once infection had occurred. Instead, often led increased across all treatments as roots became progressively compromised their take up water. Results show that after has occurred is unlikely effectively control rot. Species used this study: species (Phytophthora Rands; T. Jung T.I. Burgess); rhododendron, Rhododendron catawbiense Michx. ‘Album', ‘Roseum Elegans', Pink'.