3. SPECIFIC CONTROL PLANS FOR HIGH PRIORITY WEED SPECIES

Scientific name: Lythrum salicaria
Common name: Purple loosestrife Updated 07/2002
A. PRIORITY #1
B. DESCRIPTION Purple loosestrife is a perennial herb native to Europe and Asia. It was introduced to North America in the 1800’s for use as an ornamental and by beekeepers. It occurs widely in wet habitats, but also in roadside ditches, on river and stream banks, and at the edges of lakes and reservoirs. A single stalk can produce 300,000 seeds and densities as high as 80,000 stalks per acre, with the potential of producing as many as 24 billion seeds per acre. The seeds can remain viable even after 20 months of submergence in water. Seed set begins in mid-to-late July and continues through late summer. Seeds may be dispersed by water, wind and in mud attached to animals. Purple loosestrife also spread vegetatively. Root or stem segments can form new flowering stems. Muskrat cuttings and mechanical clipping can also contribute to rapid spread by floating in riverine and lacustrine systems. Purple loosestrife lacks natural enemies in the United States.
C. CURRENT DISTRIBUTION ON THE SITE SEE APPENDIX 2, MAP #2
D. DAMAGE & THREATS Purple loosestrife quickly crowds out most native vegetation in marsh, fen, sedge meadow, and wet prairie communities, creating a monoculture that provides little food or shelter for native wildlife. Once established, it can destroy marshes and wet prairies and choke waterways.
E. GOALS The major goal the MNWAG wants to accomplish is to lessen the economic impact caused by purple loosestrife by eradicating small stands and reducing, then controlling, larger stands.
F. OBJECTIVES (Measurable) (Establish measurable objectives for the planned control activities. Include:
1. the impact on numbers, density, cover, etc. that you want to achieve;
2. the size of the area in which you hope to achieve this;
3. the period in which you hope to achieve it. For example you may state your objectives in terms of reducing percent cover of the species by 50% over an area of 5 acres within 3 years. Another possible objective would be eliminating the species from the site within 2 years.)
G. MANAGEMENT OPTIONS Viable control options are:
(1) MECHANICAL – Younger plants (1-2 years old) can be hand-pulled. Older plants, especially those in fens or in deep organic soils, can be dug out. Roots of older plants can be "teased" loose with a hand cultivator. (This option is recommended for use in areas with individual plants and clusters of up to 100 plants.)
(2) CHEMICAL – Spot application of a glyphosate herbicide to individual purple loosestrife plants is the recommended treatment where hand pulling is not feasible. Glyphosate is available under the trade names Roundup and Rodeo, products manufactured by Monsanto. (This option is recommended for use in easily accessible areas with clusters in excess of 100 plants – up to or greater than 4 acres in size.)
(3) BIOLOGICAL – Galerucella calmariensis and G. pusilla are considered host-specific to purple loosestrife (Lythrum salicaria), and are currently being utilized for the control of loosestrife on the Niobrara Valley Preserve and surrounding entities. These European beetles have very similar life habits. Adults emerge in spring from hibernation in leaf litter and feed on the new leaves and shoots of purple loosestrife. The egg laying phase lasts approximately two months in the spring and eggs are laid in clusters of two to ten daily on the plant stem and in the leaf axils. A female can lay 300-400 eggs per year, and the adult lives 8-10 weeks. Larvae feed on bud, leaf, and stem tissue. Pupation takes place in the soil or ground cover near the plants. From egg to adult takes about 6 weeks and there is generally one generation per year. Adults are very mobile and successful in seeking out new stands of purple loosestrife. Most searching for a host plant occurs after hibernation when plant growth is at a peak, and again following the emergence of new beetles in July and August. Once a host has been located, migration slows. The overwintered adults die by late June, soon after the reproduction phase has been completed
H. ACTIONS PLANNED (Treatments and monitoring) (Briefly describe the locations to be treated, materials and methods to be used, and an approximate schedule for control and monitoring activities. If several methods are to be tested, outline the design of the planned experiment or demonstration.)
I. HOW ACTIONS WILL BE EVALUATED (Criteria for success) SEE APPENDIX 4: Examples of forms that are currently being utilized by the Niobrara Valley Preserve.
J. RESOURCE NEEDS SEE APPENDIX 3: Weed Management Plan Tables
K. RESULTS OF EVALUATION (This section is to be filled in later, preferably within 1 year, when monitoring data has been taken and evaluated, at least preliminarily. The evaluation should be used to determine whether any of the sections B-K above should be modified.)