2001 Annual Report for FS01-136
A Natural Control for Algae in Virginia Farm Ponds
Summary
There are about 60,000 farm ponds in Virginia that are susceptible to excessive growth of algae which can cause a number of problems in water throughout the South. Many algae can be controlled by chemical herbicides but, unfortunately, herbicides that control algae also kill higher plants. Once the water is temporarily cleared of all plants and the herbicide has gone from the water, the re-growth of algae can take-off unhampered by light and nutrient competition from the higher plants.
The most common herbicide used for algae control is copper sulfate. This product provides effective short-term control of algae, but is also toxic to non-target organisms such as zooplankton and insect larva that are important food sources for fish. The copper algaecides need to be re-applied several times each year and the long-term buildup of copper in pond sediments may become an environmental and health concern. Furthermore, organic certification programs do not allow the use of copper algaecides in water for livestock or in irrigation water for organic crops. Landowners who have been able to have their farms certified for organic production need alternative forms of algae control.
Researchers have learned that barley straw is a simple, cost-effective alternative method for controlling algae. Members of the Virginia Fish Farmers Association, in four different regions of Virginia, will conduct on-farm trials to compare the use of barley straw with copper algaecides for control of algae. Three treatments will be established in three separate ponds in each of the four regions. The treatments are:
1.) Control of algae using plain bales of barley straw at a rate of two bales per surface acre;
2.) Control of algae using barley straw in floating mesh bags at a rate of two bales per surface acre;
3.) Control of algae using copper sulfate (Cutrine Plus) according to directions on the label.
Measurements of algal growth will be made and recorded by the cooperating farmers every week from April 15 until October 15. The pond owners will also measure algal growth by visual observation of the entire pond throughout the year.