This Test Guideline is designed to assess the toxicity of chemicals on the growth of submerged aquatic plants Myriophyllum spicatum growing in a sediment-free test system.

In a modified Andrews’ medium Myriophyllum spicatum plant cultures are exposed to at least five different concentrations of the test chemical over a period of 14 days. A minimum of 10 replicates for the controls and 5 replicates for each test concentration should be used. The measured variables include growth of shoot length, of lateral branches and roots, development of fresh and dry weight, increase of whorls. Both average specific growth rate (r) and yield (y) are determined and then used to expressed ErCx and EyCx respectively (x can be eg. 10,20,50)

In addition, the lowest observed effect concentration (LOEC) and the no observed effect concentration (NOEC) may be statistically determined.