Cultural Control of purple loosestrife or lythrum (Lythrum salicaria, L. virgatum, and any hybrid cross thereof)
Tilling (Plowing): Not an effective method because the root crown (what hold the seeds) is under the soil. When you till the soil it spreads the seeds around (5). And, the roots are too deep for tilling to kill (2).
Hand Pulling and Hoeing: This method is only known to be effective for small infestations and outcroppings. If you choose to use this method make sure to get the whole root and not just tear it off. The seeds are located underground so be sure to dig out all of the plant (2).
Controlled Burning: This method is not effective because this plants crown (where the seeds are kept) is about 2 cm below the surface of the soil. This keeps them pretty well insulated from fire. When the fire is over the seeds will repopulate the area (1).
Seeding/Reseeding: Reseeding has been found to be effective if you plant cat tails along with raising the water level. This method of cultural control is not recommended however because it is found that most plants able to take over the purple loosestrife will eventually end up being just as big a problem as the weed was in the first place (1).
Watering: Raising the water level to control the outbreak of purple loosestrife has been found to be unsuccessful at times, but has also been found to be successful. It has been found that mature plants will survive when submerged in 2 or 3 feet of water for up to 3 years. If you submerge young plants fully under water they will die after 1 year (1,3).
Chaining or bulldozing: This method is most effective if it is done before the plants get their flowers. If it is done too late the new seed may already have germinated. If you use this method be sure to bag all cuttings. This method is not recommended, however, because the seeds usually fall out during the process, and also the seeds are usually left underground (3).
Grazing Methods: Grazing is an unusable method because purple loosestrife is found in swampy areas where grazing animals do not tend to live (4).
Mowing: The method of mowing is not effective because of the crown root being under the surface. This meaning that if you do not get the plant in its immature stage there are seeds under the surface so mowing off the top of the plant is ineffective (3).
1. "Integrated pest management", Spread Impact and Control of Purple Loosestrife in North America, Great Plains Organization, <http://www.greatplains.org/npresource/1999/loosstrf/integrat.htm>.
2. "Purple loosestrife: what you can do and what you should know", Outreach, Sea Grant Minnesota, Mar 9, 2004, <http://www.seagrant.umn.edu/exotics/purple.html >.
3. "Purple loosestrife management program", Ecological Services, Minnesota DNR, Mar 9, 2004, <http://www.dnr.state.wi.us/org/land/er/invasive/factsheets/loosecontrol.htm >.
4. "Say no to purple loosestrife", Purple Loosestrife, Missouri Purple Loosestrife, Mar 9, 2004, <http://www.mdc.mo.gov/nathis/plantpage/flora/purple/>.
5. "The problem", Purple Loosestrife, Canadian Diversity, Mar. 11, 2004, <http://ww2.mcgill.ca/biology/undergra/c465a/biodiver/2000/purple-loosestrife/PLProblem.htm>.
By: Clara Schahczenski 3/11/04
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