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.
Duckweed can quickly take over the surface of the pond, decreasing oxygen levels necessary for fish and desirable aquatic plants to live there. Visiting Canadian geese, agricultural and animal lot runoff, lawn fertilizer and septic tanks that do not work properly contribute to high nutrient levels.