Biological Control Of Pythium In Aquaponic

Infection of plant roots by zoosporic pathogens in hydroponic vegetable culture is a recognizedmajor problem in the industry, reducing production and limiting growth of the industry.Hydroponic nutrient solutions provide ideal conditions for the rapid spread of zoosporicpathogens - continuously moist conditions, stable temperatures, uniform host plants, and anaqueous nutrient solution which is continuously recirculated. No effective chemical controlagents are currently registered for use in the U.S.Aquaponic systems, which integrate fish culture with hydroponic vegetable culture, are alsoaffected by zoosporic pathogens. In these systems, fish not only produce nutrients for the plants,via their fecal matter and other excretions, but live in the nutrient solution as well. As a result, anapproach used to control zoosporic pathogens must take into account the chemical sensitivity offish and the nitrifying bacteria needed to treat their effluent.The proposed work will evaluate the effectiveness of three different control measures forPythium: 1) a species of fungi, Gliocladium virens, 2) a species of bacteria, Burkholderiacepacia, and 3) the effectiveness of the addition of stabilized fish sludge to the bottom ofhydroponic tanks as a method of creating a complex of micro-flora capable of out competingPythium.