Building Crop Health into Water Recycling Systems

Authors: KONG, PING - Virginia Polytechnic Institution & State University; RICHARDSON, PATRICIA - Virginia Polytechnic Institution & State University; YANG, XIAO - Virginia Polytechnic Institution & State University; ZHANG, HAIBO - Virginia Polytechnic Institution & State University; GHIMIRE, S - Virginia Polytechnic Institution & State University; MOORMAN, G - Pennsylvania State University; LEA-COX, J - University Of Maryland; Copes, Warren; ROSS, D - University Of Maryland; RISTVEY, A - University Of Maryland; BOYLE, K - Virginia Polytechnic Institution & State University; BOSCH, D - Virginia Polytechnic Institution & State University; PEASE, J - Virginia Polytechnic Institution & State University; HONG, C - Virginia Polytechnic Institution & State University

Submitted to: International Plant Protection Congress
Publication Type: Abstract Only
Publication Acceptance Date: 5/6/2015
Publication Date: 8/1/2015
Citation: Kong, P., Richardson, P., Yang, X., Zhang, H., Ghimire, S.R., Moorman, G.W., Lea-Cox, J.D., Copes, W.E., Ross, D.S., Ristvey, A.G., Boyle, K.J., Bosch, D., Pease, J., Hong, C.X. 2015. Building Crop Health into Water Recycling Systems. International Plant Protection Congress. O IRR 1:119.

Interpretive Summary:

Technical Abstract: Introduction Plant pathogens in irrigation water present a growing threat to crop health as agriculture increasingly depends upon recycled water for irrigation. A variety of decontamination technologies have been introduced from municipal water treatments to mitigate this risk, but their technical and economic performance is often compromised in the agricultural settings due to turbidity, organic and inorganic contents. There is an urgent need for long-term solutions to this emerging crop health issue of global significance. Objectives The ultimate goal of our studies was to help farmers build science-based water recycling systems that capture and reuse agricultural runoff without recycling pathogens. Specific objectives included: 1. Investigating pathogen spatial distribution in water recycling systems using Phytophthora species as an example 2. Developing a better understanding of recycled water quality dynamics 3. Elucidating zoosporic responses to major water quality stresses in a simulated aquatic system. Materials and Methods Pathogen dynamics was tracked by baiting with rhododendron leaves, followed by plating onto selective media, and identification of resultant cultures by DNA fingerprinting and sequencing, and morphological exam. Water temperature, pH, dissolved oxygen, oxidation-reduction potential, electrical conductivity, salinity, total dissolved solids, turbidity, chlorophyll, blue and green algae were continuously monitored at multiple reservoirs in different U.S. states. Using these field data as a framework, zoosporic responses to major water quality stresses were assessed for a number of Phytophthora species including P. ramorum, P. kernoviae, P. alni. Results Pathogen populations declined along the water path from runoff entrance to outlet in irrigation reservoirs. Water quality changed dramatically overtime and diurnally. Most Phytophthora species assessed are intolerant to water quality stresses. Conclusions Many pathogens including some Phytophthora species, which collectively have been perceived as “water molds”, are not well adapted to agricultural reservoir environments. Crop health risk associated with irrigation water may be effectively managed by extending runoff water path, and/or increasing turnover time in recycling irrigation systems.