Controlled Environment Agriculture

Pythium Root Disease - Note two projects!

1. Characterization of the Effects of Innoculation Time and Nutrient Solution Temperature on the Development of Pythium aphanidermatum Infection of Full-Size Spinach

Leslie Katzman

A major problem with continuous hydroponic spinach production is root disease. The CEA program continues to focus on methods to reduce disease in order to grow plants on a commercial scale. We constructed special hydroponic tanks with a high level of computer-automated, environmental control. These tanks were used to study the influence of root zone temperature and oxygenation on:

  1. The development of the root disease pathogen, Pythium aphanidermatum.
  2. The growth of the plant in the absence or presence of this pathogen.
  3. The effect on biomass, pathogen population and root health due to:
    • Time of inoculation
    • Concentration of inoculm
    • Root zone temperature

Results of this work may be found in:

Katzman, Leslie Simone. 2003. Influence of plant age, inoculum dosage, and nutrient solution temperature on the development of Pythium aphanidermatum in hydroponic spinach (Spinacia oleracea L.) production systems. PhD Dissertation, Cornell University. Ithaca, NY 14850

The research project was funded by NYSERDA and NYSEG.

2. Root Disease Treatment Methods for the Commercial Production of Hydroponic Spinach

David de Villiers and Tim Shelford

Pythium aphanadermatum is a devastating root disease organism to which spinach is particularly susceptible. This disease has prevented successful hydroponic spinach production in the United States.

Several conventional and one novel nutrient solution cleansing methods (ultraviolet radiation, sonication, filtration, and electrochemical treatment) were evaluated to determine their efficacies in suppressing disease in continuous production for at least as long as required for baby-spinach to reach harvest (approximately two weeks after germination). None of these methods worked in a deep-flow hydroponic system.

A method was developed that allowed the production of a commercial-quality crop within 14 days was developed. This included reducing the nutrient solution temperature to 20 C (68 F).

A surer method was to create sequential production ponds where plants are moved from one to a second part-way through the production cycle. The method is believed to work by taking advantage of the disease reproduction period, which appears to be approximately 15 days at 20 C. This method requires limited refrigeration capacity in an insulated deep-pond system of commercial size but does absolutely require supplemental lighting and daily light integral control to achieve sufficient productivity within the allowable production period before disease strikes, as it will.

Aeroponics production was contrasted to deep-pond production.

To view the final report for this project: Download Baby Spinach Pythium Treatment Methods