HERBICIDES AND ALGICIDES
Excessive biomass of rooted aquatic plants can interfere with
uses of the water and may produce organic substances in the water,
which lead to dissolved-oxygen depletions or to problems-with taste, odor, and
Nuisance "blooms" of
algae, often blue-green algae, can also produce the same problems.
Herbicide and/or algicide applications are used to kill the plants, and
together represent one of the most commonly used means of managing the symp-
There are few modern scientific reviews of their use.
toms of eutrophication.
However, the reader will find the following useful:
Brooker and Edwards
and Barrett (1977); Brown (1978);
(1975); Kearney and Kaufman (1975);
Janik, Taylor, and Barko (1980); Hanson and Stefan (1984); Westerdahl and
Theory and Design
Herbicides and algicides are applied either as liquids or granules to
concentrations known to be sufficient to produce
elimination or control of biomass, usually through interference with plant
In some instances, chemicals are used together (e.g., diquat
and copper) for
macrophyte and algal problems simultaneously, or
chemicals may be used in conjunction with other procedures such as harvesting,
carp, or insects.
Until the last 15 years, the use of chemicals to alleviate the symptoms
of eutrophication was essentially the only effective method available to
Today, other methods that are
improve or open reservoirs and waterways.
restorative or protective in nature, or with less environmental impact, have
often been substituted for them, especially where longer term control is
These methods have been described in earlier parts of the report and
In many instances, however, particularly in densely
in Cooke et al. (1986).
infested southern waters, herbicides remain as one of the more cost-effective
When the causes of excessive algae or macrophyte growth
be remedied, or while nutrient control or other restorative procedures