The effects of several herbicides on the germination of seeds in the forest floor

Abstract

In a laboratory experiment, we studied the effects of perturbation of a forest floor substrate with six concentrations (10, 50, 100, 500, 1000, and 5000 ppm) of four herbicides: glyphosate (N-phosphonomethyl glycine), 2,4,5-T (2,4,5-trichlorophenoxy acetic acid), triclopyr (3,5,6-trichloro-pyridinyloxyacetic acid), and two formulations of hexazinone (3-cyclohexyl-6-(dimethylamino)-1-methyl-1-1,3,5-triazine-2,4(1H,3H)dione). Although their toxic thresholds differ, the herbicides all caused significant decreases in the germination of seeds. However, large decreases in germination only occurred at concentrations that are unrealistically large in comparison with the herbicide residues that actually occur after a silvicultural treatment. In a parallel field experiment, no significant difference in seedling germination was observed for forest floor samples that were exposed to or shielded from herbicide deposition at two sites that were sprayed in an operational program.

Effects of competing vegetation and post-planting weed control on the mortality, growth and vole damages to Betula pendula planted on former agricultural land

“…This damage can be prevented by careful spraying with a backpack sprayer (Siipilehto 2001) or (as in this study) by using a weed-wiping applicator. Since glyphosate does not inhibit germination of seeds of the seed banks (e.g, Morash and Freedman 1989), it allowed a rapid invasion of annual weeds in the second growing season. In order to achieve a good effect on afforested fields with large seed banks, its application should be repeated in the 2nd summer.…”

Seasonal susceptibility of boreal plants: red raspberry phenology as a bioindicator of optimum within-season timing of glyphosate applications

“…This recovery may have occurred from seedling regeneration from the soil seed bank. Morash and Freedman (1989) effectively demonstrated that glyphosate has little effect on raspberry germination. Chourmouzis et al (1997) observed that the germination of red raspberry seeds from the soil seed bank were not significantly (p > 0.05) affected by rate or timing of glyphosate application and concluded that complete control of red raspberry cannot be accomplished with a single operational application of glyphosate, due to the large numbers and high viability of seed in the soil seedbank.…”

“…The species has a broad geographical distribution and has been identified as a serious competitor of crop tree species in Canada (Haeussler et al 1990, Bell 1991, Jobidon 1995. Red raspberry is an aggressive pioneer colonizer that regenerates and grows rapidly from soil seed banks (Ahlgren 1979;Graber and Thompson 1978;Whitney 1978Whitney , 1984Morash and Freedman 1989;Lautenschlager 1997). It also reproduces from axillary buds along rhizomes and from basal buds that give rise to biennial canes (Hudson 1954).…”

Relative persistence of commonly used forestry herbicides for preventing the establishment of broom (Cytisus scoparius) seedlings in New Zealand plantations

“…Herbicides with appropriate selective activity suppress competing weeds so that the desired trees can grow more quickly (Gratkowski 1975;Morash and Freedman 1989). Some herbicides, such as glyphosate, kill weeds on application and leave no residue in the soil.…”