Diseases caused by Sclerotinia spp., generally known as 'white mold', can affect hundreds of plant species including many important crops. The pathogens are favored by cool, moist conditions, but show surprisingly broad ecological distributions. 1 Several other Sclerotinia species cause diseases other than white mold.
Oxygen dissolves into water from two sources: the atmosphere and from plants in the water. The primary source of oxygen for a pond is from microscopic algae (phytoplankton) or submerged plants.In the presence of sunlight, these produce oxygen through photosynthesis and release this oxygen into the pond water.xygen dissolves in water at very low concentrations. Our atmosphere is 20% oxygen or 200,000 ppm but seldom will a pond have more than 10 ppm oxygen dissolved in itsâ water. Dissolved oxygen concentrations below 3 ppm stress most warmwater species of fish and concentrations below 2 ppm will kill some species.
Disolving Oxygen Into Pond Water. The physical nature of water puts limitations on how much oxygen we can expect our pond water to hold. It also sets targets for what we should expect to achieve under different pond conditions. In the air we breathe, there is approximately 21% oxygen (210,00ppm oxygen).In any natural water body, we will typically find less than 1% dissolved oxygen. So tiny are the concentrations of dissolved oxygen in pond water, that their levels are measured in milligrams per litre or parts per million (ppm).For example 3 milligrams of oxygen dissolved in a litre of water equates to 3 ppm.t also sets targets for what we should expect to achieve under different pond conditions. In the air we breathe, there is approximately 21% oxygen (210,00ppm oxygen). In any natural water body, we will typically find less than 1% dissolved oxygen.