Pythium spp. and its Effects on Tobacco Transplant Greenhouse Production

In North America, tobacco transplant production grows uniform, high-quality, healthy seedlings with established root systems that ensure a reliable start to the growing season and usually higher yields. Besides the goal of having more seedlings survive the early stages of germination in a controlled environment, tobacco transplant production also allows tobacco growers to extend the growing season past what the climate would allow. The seedlings are grown in expanded polystyrene [EPS] trays floating on a nutrient-rich water-based solution; however, these float-beds are also a potential breeding ground for multiple diseases if contaminated. One of the most common seedling diseases found in tobacco float-beds is Pythium root rot, also commonly known as Pythium crown rot or Pythium damping off. Pythium spp. is a genus of oomycetes with Pythium myriotylum and P. dissotocum as the two most common and aggressive causal agents of Pythium damping off in tobacco float-bed greenhouses.