An integrated management strategy for the control of purple loosestrife Lythrum salicaria L. (Lythraceae) in the Netley-Libau Marsh, southern Manitoba / D.C. Henne, C.J. Lindgren, T.S. Gabor, H.R. Murkin, and R.E. Roughley.

Includes bibliographical references (pages 324-325).

We evaluated the eVectiveness of an integrated vegetation management strategy (IVM) for the management of purple loosestrife
(Lythrum salicaria) by comparing the performance of herbicides alone (glyphosate and triclopyr amine), a biological control agent
(Galerucella calmariensis) alone, and herbicides integrated with the biological control agent. The study was conducted from 1996 to
1998 within Weld-cages placed in a 2-ha stand of purple loosestrife located in southern Manitoba. Using a randomized complete
block design, each treatment was replicated three times. Herbicides were applied in the summer of 1996 while G. calmariensis were
released at either low-densities (12 adults) or high-densities (24 adults) in 1997. We measured performance using data on Wnal stem
heights, terminal spike length, the number of Xowering spikes, and the number of seed capsules in each year and the total number of
all stems at the end of each year. Integrated treatments were found to cause signiWcant reductions in the mean number of purple
loosestrife stems. The G. calmariensis alone treatments resulted in no signiWcant change in mean stem densities; however, herbivory
reduced mean stem heights by almost 70%. Mean stem densities of purple loosestrife increased in the herbicide alone treatments
when compared to pretreatment levels. Results indicated that an IVM strategy using herbicides integrated with G. calmariensis outperformed
herbicide alone treatments and G. calmariensis alone. While further open-Weld investigations are required, these results
have important management implications.