There is a single class, Oomycetes, which is further divided into 7 orders. We shall study some genera belonging to the orders Saprolegniales, Pythiales and Peronosporales. Order Saprolegniales (Water Molds): The term 'water molds' is generally used for genera belonging to this order. The zoospores are formed in zoosporangia. A peculiar feature of this order is the production of two [...]
The following points highlight the top five evolutionary trends on Oomycetes. 1. There is progressive evolution from the aquatic to land habitat. Members of orders Lagenidiales, Saprolegniales and Leptomitales are chiefly aquatic. The advanced order Peronosporales includes aquatic, amphibious and terrestrial forms. 2. The representatives of this class show a whole range from saprophytes (Saprolegnia) to facultative parasites (Pythium) and [...]
In this article we will discuss about:- 1. Occurrence of Pythium 2. Predisposing Factors of Pythium Debaryanum 3. Mode of Infection 4. Symptoms 5. Economic Importance 6. Salient Features. Occurrence of Pythium: P. debaryanum is the classic example of the most common species of Pythium which causes the widespread "damping off" disease of tobacco, tomato, mustard, chillies and cress seedlings. [...]