Pythium Species and Population Identification Using DNA Markers
Many species of the fungus, Pythium, cause damping off, and rots of roots, stems, and cuttings. In roots, some species found are very weak parasites while others are beneficial because they attack other disease-causing fungi rather than the plant roots. Thus, it is very important to accurately identify the species associated with plants. Pythium can be found in soil carried in from outside the greenhouse, in peat or soilless potting mixes, and in pond and stream water. It can be brought into the greenhouse on infected cuttings or plugs purchased from another greenhouse. Once in the greenhouse, it survives in crop debris and soil on or under benches. It is important to know where the disease causing Pythium originated so control measures can be aimed at that source. This means that we must be able to tell for example, whether the Pythium ultimum causing crop losses is the same or different from the Pythium ultimum we might find in soil under the bench or in plants purchased from a supplier.
Source: • American Floral Endowment Special Research Reports #109