Transport of Phytophthora Capsici Zoospores in Saturated Sand Media.

Phytophthora capsici has been detected in surface water in the U.S. and elsewhere. Contaminanted surface water used for crop irrigation has been a significant contributor to increased incidence of Phytophthora-infested vegetable fields and associated crop losses. In order to mitigate and prevent the outbreaks of vegetable diseases, mechanistic understanding on factors governing environmental transport of Phytophthora is essential. This study aims to study the transport and retention of P. capsici zoospores in saturated columns packed with iron oxide coated-sand (IOCS) and uncoated-sand under Na⁺ or Ca²⁺ solutions at pH 4 or 7.8. The recovery of biflagellate zoospores in column effluent was higher than that of encysted zoospores. P. capsici encysted zoospores were removed up to 98% in the IOCS column and up to 96% in the uncoated-sand column. The removal efficiencies of P. capsici encysted zoospores were significantly lower in IOCS and in uncoated-sand (p <0.05). However, there was no statistically significant difference between Na⁺ and Ca²⁺ treatments. Low pH and high iron content reduced the effluent recoveries of encysted zoospores. This study has broad implications in environmental transport of Phytophthora zoospores in natural soils as well as in cost-effective engineered treatment systems (e.g., sand filtration) for Phytophthoraremoval.