Citrus trees were irrigated via furrows or low-volume emitters, and populations of Phytophthora parasitica from the rhizosphere were monitored over a period of 12 days after irrigation by soil dilution plate assay on a selective medium. The types of propagules present under long- and short-interval irrigation regimes were quantified from November through August. Populations of P. parasitica increased from 17 propagules per gram (ppg) the day before irrigation to 70 ppg 2 days after long-interval furrow irrigation. Populations ranged from 71 to 93 ppg with short-interval drip irrigation (.)