Controlling Parrotfeather

Parrotfeather is a submerged/emerged member of the water milfoil family.  It is very aggressive and originates in South America.  It has become acclimated to the southern U.S., as well as up the West coast into Washington.  In order to effectively control parrotfeather, only one option may be viable at this time – chemical.

Although parrotfeather is considered by some to be susceptible to herbicides, it is difficult to achieve complete control. The emergent stems and leaves have a thick waxy cuticle and it requires a wetting agent to penetrate this cuticle. Often the weight of the spray will cause the emergent vegetation to collapse into the water where the herbicide is washed off before it can be translocated throughout the plant. Some researchers report excellent control of parrotfeather with several herbicides including 2,4-D (Navigate), diquat (Tsunami DQ), and endothall (Aquathol). Fair control was obtained with glyphosate. Glyphosate with surfactant applied to the plants in the summer or fall when water levels are low has given about 95 percent control of the plants in tests. The granular formulation of 2,4-D was needed to control parrotfeather for periods greater than 12 months. Diquat Dibromide seems effective at the rate of 2 gallons per surface acre inhabited by parrotfeather.  It is more effective when applied to young, actively growing plants. More recently imazapyr and triclopyr have been used to manage parrotfeather, showing some promising results.

In actual practice, the weed managers report that they must make repeated treatments with herbicides in order to make any permanent progress. In practice, where the goal is eradication, you should use multiple herbicides, multiple times per treatment season, over a number of years and yet you could still have persistent plants. However, each year the biomass is reduced and with time and persistence, you should achieve your eradication goal.

For more information about pond weed control contact the helpful staff at Sanco.