Pythium

Pythium is a genus of organisms which cause common crop diseases such as Pythium root rot, Pythium fruit rot and in seedlings can cause Damping off. These are commonly called water moulds. Pythium damping off is a very common problem in fields and greenhouses, where the organism kills newly emerged seedlings, usually as a result of overwatering.

Root rot
The disease first appears as irregular areas of wilted, yellowed, stunted, or dead plants. These symptoms are the result of girdling of the lower stem of the plants by either Rhizoctonia or Pythium fungi species. Pythium usually affects the young plant near the soil line. A soft, brown, watery rot girdles the stem, causing the plants to fall over. Plants affected after stems harden may not die but turn yellow due to injury to the stem and root system. Pythium sometimes attacks transplants shortly after they are set in the field, causing a stem rot.

Fruit rot
Initially the fruit lesions are brownish, water soaked, and soft. Often infection starts on tissue in contact with soil.

Treatment
Destroy plant and pot. Ensure area where plant was is sterilised sufficiently to avoid contamination of other plants. If you want to save your plant you can do so by moving it to another room, Remove any dead or dying tissue including roots, stems and leaves and shake of all soil. Anywhere an infected part was removed should be dusted with sulphur to prevent further infection. Repot the plant in fresh, sterilised soil. Water from the bottom and do not overwater. Do not fertilise until plant is re-established (4-6 weeks).

Prevention
Maintain a plant water temperature between 18-20°C (64-68°F) or at least avoid temperatures above 21°C (70°F). Keep plant nutrients fresh by feeding every 7 days.