Water primrose: Chemical control using herbicides
Overall effectiveness category Likely to be beneficial
Number of studies: 3
Background information and definitions
Application of chemical herbicides may offer a tool for management of water primrose Ludwigia spp. provided regulatory approvals are in place. For example, glyphosate has been reported to have successfully eradicated water primrose Ludwigia spp. at three UK sites (Renals 2010).
Adjuvants are agents that can modify the effect of chemical herbicides, thereby increasing their effectiveness. It has been reported that there is a synergistic benefit of applying an adjuvant such as TopFilm alongside glyphosate. It is reported that the combined use of herbicide and adjuvant has eradicated various small stands of large-flower primrose-willow (Newman 2008). A review also references the potential for synergistic application of glyphosate and TopFilm, reporting the most effective application rates to be 2.28 kg of glyphosate and one litre/ hectare of TopFilm, and reporting June and July to be the best time for application (Plant Protection Service at al. 2011).
Renals, T. (2010) Ludwigia Eradication: A Rough Model for the Future. Proceedings of the 42nd Robson Meeting, CEH, Wallingford, UK. 1pp.
Newman J R (2008). Aquatic Weed Control. Proceedings of the 40th Robson Meeting. CEH, Wallingford, UK. 1pp.
Plant Protection Service, Plant Research International Wageningen UR, Aquatic Ecology and Water Quality Management Group & Centre for Ecology and Hydrology Wallingford (2011) EUPHRESCO DeCLAIM Final report A State of the art June 2011. Ludwigia grandiflora (Michx.) Greuter & Burdet. 63pp.
Supporting evidence from individual studies
A controlled, replicated laboratory study conducted in 2007 in the USA (Champion et al. 2008) found that the herbicide triclopyr TEA (triethylamine) stopped the growth of young cultivated creeping water primrose Ludwigia peploides in comparison to untreated plants. Plants stopped growing and were damaged at concentrations of 0.25% by volume and above. Within two months, 0.25 % triclopyr TEA killed 100 % of treated creeping water primrose. Creeping water primrose seedlings were collected from the wild and cultivated in glasshouses. The plants were grown in water-filled 40 litre tubs containing a bed of sand for at least two months. Herbicide was applied to run off at between 0.25% and 5.00% concentration by volume. Ten plants were tested at each concentration and monitored regularly for signs of herbicide damage. Ten plants were left untreated as controls.Study and other actions tested
A before-and-after field study conducted from 2006 to 2007 in the UK (Centre for Ecology and Hydrology 2007) found that the herbicide glyphosate combined with a non-oil soya sticking agent, reduced the abundance of creeping water primrose Ludwigia peploides. After 56 days, the biomass of creeping water primrose was reduced by over 97% compared with the biomass before treatment. When glyphosate was combined with TopFilm, it reportedly killed the plant. A solution of 360g/litre of glyphosate (Roundup Pro Biactive) was applied at a rate of 6 litres/ha and the non-oil soya sticking agent was applied at a rate of 450 ml/ha. Further details of the experimental treatments, such as area treated, are not provided.Study and other actions tested
A controlled, replicated, randomized study at the National Institute for Agricultural Research, Venezuela (Suárez et al. 2004) found that use of the herbicide halosulfuron-methyl (Sempra) resulted in a significant reduction in water primrose Ludwigia spp. coverage without apparent toxicity to rice plants. Treatment of 60 g active ingredient/ha produced the highest percentage control, with average reduction in water primrose coverage of 80%. The trial was conducted in a randomized block design with five treatments and four repetitions. Treatments were undertaken in experimental plots marked with fixed 0.25m2 metal frames. Sempra, formulated as water dispersible granules at a concentration of 75% halosulfuron-methyl by weight, was applied to rice crops 26 days after sowing at the following range of doses 0, 15, 30, 45 and 60 g active ingredient/ha. The herbicide was applied with a manual sprayer. Weed coverage and rice crop quality were then evaluated.Study and other actions tested