Eliminating Phytophthora spp. from stream water throughout the year with algaecides.

Abstract

Due to the aquatic nature of oomycetes, Phytophthora spp. can be found in a wide variety of waterways in and around natural and agricultural ecosystems—including forest streams, urban streams, and irrigation ponds. They are disseminated effectively and efficiently in flowing water, so Phytophthora spp. can be moved readily from an infested area (e.g., a nursery) to nearby non-infested environments if waterways in the infested area become contaminated with propagules of the pathogen. This type of dissemination—particularly for exotic species like P. ramorum—poses a serious threat to plants in urban and natural environments that are in the vicinity of an infested area. General biocides such as chlorine, hydrogen dioxide, ozone, and UV radiation currently are used to eliminate pathogens (including Phytophthora spp.) from water. Different types of filtration systems utilizing both physical and biological barriers also are being used, but mainly for irrigation water. However, these options usually are not practical or feasible when an immediate eradication of a recently introduced pathogen is required. Oomycetes are closely related to brown algae. In previous research, we demonstrated that algaecides, particularly those with copper-based active ingredients, are very effective at eliminating Phytophthora spp. from artificially and naturally infested water samples. All of the algaecides tested are registered for use in a variety of waterways—including agricultural irrigation systems, fish ponds and hatcheries, fresh water lakes, and potable water reservoirs. Previous studies demonstrated that there was seasonal variation in the distribution of Phytophthora spp. and densities of these species in streams. Therefore, we examined the ability of commercial algaecides to eliminate Phytophthora spp. naturally occurring in two streams throughout 2010.

Parent Publication

• Proceedings of the sudden oak death fifth science symposium

Citation

Meadows, Inga M.; Hwang, Jaesoon; Jeffers, Steven N. 2013. Eliminating Phytophthora spp. from stream water throughout the year with algaecides. In: Frankel, S.J.; Kliejunas, J.T.; Palmieri, K.M.; Alexander, J.M. tech. coords. Proceedings of the sudden oak death fifth science symposium. Gen. Tech. Rep. PSW-GTR-243. Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Research Station: 48-50.