pathogens & biofilm (13)

26 Apr 2018

Test Your Irrigation Water for Phytophthora

Redekar, N.R. and Parke, J.L. (Oregon State University)

Phytophthora is a plant pathogen that can infect a wide variety of nursery plant species, and it spreads in irrigation water. In this article, we will describe how you can test your irrigation water for Phytophthora using baits. We present a case study of a large nursery where baiting was used to test the efficacy of their water treatment. Although this nursery recycles 90% of their irrigation water, we showed that they were successful at controlling Phytophthora contamination with their chlorination treatments.

Haga clic aquí para leer el artículo en español.

American Nurseryman Redekar and Parke 2018 (657 KB)

6 Apr 2018

Phytophthora Communities in a Western Oregon (USA) River

Redekar, N., Eberhart, J., and J.L. Parke (Oregon State University)

One source of oomycete (Phytophthora and Pythium) contamination in nurseries and greenhouses is the use of untreated water from ponds and rivers. Next generation DNA sequencing was used to detect species of Phytophthora and Pythium in irrigation water originating from a river.  Research highlights: 1) Pythium and Phytophthora are the most abundant oomycete genera found in river water, 2) the oomycete species in river water fluctuate seasonally, 3) leaf baiting is the best method to detect active plant pathogens, particularly Phytophthora species, and 4) next generation sequencing technology is a very effective, sensitive and semi-quantitative method for detecting Phytophthora and Pythium in water or soil. 

Take home message for growers: 1) surface water (rivers and ponds) are almost always contaminated with Phytophthora and Pythium species, 2) water can be tested using leaf baiting to determine if Phytophthora is present 3) water should be disinfested before use in irrigation.

Poster IUFRO Redekar et al (724 KB)

19 Mar 2018

Slow Sand Filters

Pitton, B.J.L., Oki, L.R. (University of California Davis), White, S.A (Clemson University)

Slow sand filters (SSF) can provide high-quality water from untreated sources like irrigation runoff. SSFs consist of a sand bed with about three feet of water above that flows through the sand via gravity. A microorganism community develops on the sand that has the ability to remove plant pathogens, including water molds, viruses, bacteria, and fungi. Flow rates are approximately six inches per hour so they can occupy a large area if sizable volumes of water need to be treated. However, SSFs are simple to install and are fairly cheap to operate compared to other treatment technologies.

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Description of research activities

A national team of scientists is working to encourage use of alternative water resources by the nation’s billion-dollar nursery and floriculture industry has been awarded funds for the first year of an $8.7 million, five year US Department of Agriculture – National Institute of Food and Agriculture –Specialty Crop Research Initiative competitive grant.

The team will develop and apply systems-based solutions to assist grower decision making by providing science-based information to increase use of recycled water.  This award from the NIFA’s Specialty Crop Research Initiative is managed by Project Director Sarah White of Clemson University.  She leads a group of 21 scientists from nine U.S. institutions.

Entitled “Clean WateR3 - Reduce, Remediate, Recycle – Enhancing Alternative Water Resources Availability and Use to Increase Profitability in Specialty Crops”, the Clean WateR3 team will assist the grower decision-making process by providing science-based information on nutrient, pathogen, and pesticide fate in recycled water both before and after treatment, average cost and return-on investment of technologies examined, and model-derived, site specific recommendations for water management.  The trans-disciplinary Clean WateR3 team will develop these systems-based solutions by integrating sociological, economic, modeling, and biological data into a user-friendly decision-support system intended to inform and direct our stakeholders’ water management decision-making process.

The Clean WateR3 grant team is working with a stakeholder group of greenhouse and nursery growers throughout the United States.

For example, at the University of Florida graduate student George Grant is collecting data on removal of paclobutrazol, a highly persistent plant growth regulator chemical, from recirculated water using granular activated carbon (GAC) filters. This is being done in both research greenhouses and in a commercial site. The GAC filters can remove more than 90% of chemical residues, and are proving to be a cost-effective treatment method.