Bioactive Natural Products: A feasible method of organic disease management in float bed production systems
Dispersal of root pathogens is a major concern in greenhouse cultivation of transplants and market garden crops. The soilborne plant pathogens Pythium and Rhizoctonia are nearly impossible to exclude from greenhouse systems and enter through irrigation water (Jarvis, 1992) and greenhouse propagation mixes. In float bed systems, as in hydroponics systems, the high plant density and high moisture conditions favor the development and dispersal of seedling diseases. We proposed to determine the cost effectiveness of disease control in float bed systems using bioactive natural products. Based on our market research, we found that there is unlikely to be a market for float bed tomato transplants.
We have recently begun experiments in a University of Tennessee greenhouse designed for commercial tomato production. These experiments have several objectives. 1)To compare plant yield and disease control in a greenhouse where biopesticides approved for organic agriculture will be applied, with disease control and plant yield in a greenhouse where standard chemical pesticides will be applied. 2)To determine the effects of different formulations and dosages of Monarda herbage for control of Pythium disease, and growth and yield of greenhouse tomatoes
3)To determine and compare the effects of seed treatment with different isolates of Beauveria bassiana for control of Pythium disease, and growth and yield of greenhouse tomatoes
4)To determine and compare the effects of different plant growth-promoting rhizobacteria for control of Pythium disease, and growth and yield of greenhouse tomatoes
In December, tomato seeds were treated with Beauvaria isolates or left untreated and planted. In January, the seedlings were transplanted to perlite growth medium in 13.64-liter (3-gal) plastic bags in the production greenhouse. All plants receive trickle fertigation. At transplanting, plant growth-promoting rhizobacteria (commercial formulations) were added to designated treatments. Inoculum of Pythium myriotylum was added at transplanting to designated transplants. To date, all plants have produced flowers and most have set fruit. We have collected data on height of plants at transplant, time of fruit on-set, and time for plants to reach 2.0 m in height. Data have not been analyzed.