Invasive Ludwigia management plan

Published source details Sears A.L.W., Meisler J. & Verdone L.N. (2006) Invasive Ludwigia management plan. Sonoma State University and Marin/Sonoma Mosquito and Vector Control District, Sonoma, California report.
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This study is summarised as evidence for the following.

	Action	Category
	Water primrose: Physical removal Action Link
	Water primrose: Combination treatment using herbicides and physical removal Action Link

Water primrose: Physical removal

A study in 2005 in a managed wetland in the Laguna de Santa Rosa, California, USA (Sears et al. 2006) found that hand pulling and raking water primrose Ludwigia sp. failed to reduce its abundance, whereas hand-pulling from the margins of a pond in the Laguna Wetland Preserve Sebastopol successfully eradicated a smaller population of water primrose. Attempts to reduce the coverage of primrose in the Laguna de Santa Rosa, California, were wholly unsuccessful and by the end of the season water primrose covered 100% of the pond. Hand pulling and raking were carried out for 2-6 person hours/week. Workers in the Laguna Wetland Preserve at Sebastopol spent approximately 150 person hours of effort hand-pulling water primrose from pond margins.
Water primrose: Combination treatment using herbicides and physical removal

A study in 2005 in the Laguna de Santa Rosa, California (Sears et al. 2006) found that application of glyphosate and a surface active agent called Cygnet-Plus followed by removal by mechanical means resulted in a 75% kill rate of a long-standing population of water primrose Ludwigia spp. and removal of 5,388 tonnes of water primrose plants. However, in some areas of incomplete kill, there was rapid regrowth. Following the eradication attempt, there was heightened turbidity. However, intensive water quality monitoring revealed very low levels of glyphosate and associated metabolites. The herbicide was applied in July 2005 from the bank, using spray hoses located on the back of specialised vehicles. It was therefore necessary to drive over water primrose located in the flooded wetland, thereby covering some with muddy water prior to spraying. Channel areas (47 hectares) were sprayed from shore. Quantitative and qualitative vegetation monitoring were carried out before and during the project.