|Evaluation of Alternative Methods for Managing
Algae in Ca - 2008
Project Leader and Principal Investigators
David Spencer,ecologist, USDA/ARS, Exotic and Invasive Weeds Research Unit, Dept. of Plant Sciences, UC Davis
Research continued in 2008 on methods to control filamentous algae in California rice fields. Laboratory and field studies focused on the effects of water quality in rice fields and various algaecides on the growth of Nostoc, a problematic blue-green algae in some fields.
Rice field water quality
How water quality conditions affect the growth of Nostoc and the effectiveness of control measures was the objective of one area of research during 2008.
In a laboratory, scientists examined the growth of Nostoc under a range of sodium concentrations in water samples. Additional parameters tested included the algaecide Rice Cop 5, light levels, water temperature, and the presence of iron.
Highlights of this work on Nostoc show:
Phosphorous management is a key element in effective control of Nostoc. In 2008, a field study compared four different phosphate fertilizer applications:
Algal biomass was lowest in field that received the 30-day, after-flooding treatment. These fields had 72 percent to 88 percent less algal biomass than fields receiving conventional phosphate application (surface-applied liquid phosphate followed by a roller). The results show that this treatment was clearly the most effective application method.