Lythrum salicaria(Purple Loosestrife) Control with Herbicides: Multiyear Applications

Abstract

AbstractThis study evaluated the effectiveness of 14 herbicide treatments for purple loosestrife (Lythrum salicariaL.) control over a period of 10 yr. The study commenced in 2000/2001 at four wetland locations in Nebraska. The evaluated herbicides included: glyphosate at 2.2 and 3.4 kg ha−1; 2,4-D dimethylamine at 1.4 and 2.8 kg ae ha−1; triclopyr at 1.3 and 2.1 kg ae ha−1; imazapyr at 1.1 and 1.7 kg ae ha−1; metsulfuron at 0.042 and 0.084 ai kg ha−1; fosamine at 13.5 and 22.4 kg ai ha−1; triclopyr at 1.3 kg ae ha−1plus 2,4-D amine at 1.4 ae kg ha−1; and metsulfuron at 0.042 kg ai ha−1plus 2,4-D amine at 1.4 kg ae ha−1. Some treatments provided excellent control (90%) that lasted only one season, while others suppressedL. salicariagrowth for multiple seasons, depending on the location and the age ofL. salicariastand. Application of higher rates of glyphosate, imazapyr, and metsulfuron consistently provided excellent control (≥90%) ofL. salicariathat lasted 360 d after treatment at most locations. Application of fosamine and the lower rate of 2,4-D amine provided the leastL. salicariacontrol at most locations. The older theL. salicariastand, the more multiple applications of herbicides were needed to completely controlL. salicaria. Generally, there were higher percentages of grasses in the 2,4-D-, triclopyr-, and metsulfuron-treated plots compared with higher percentages of broadleaf species in the glyphosate- and imazapyr-treated plots at each location.