Herbicidal Control of Common Milkweed (Asclepias syriaca)

Abstract

Five field experiments were conducted to evaluate effectiveness of postemergence herbicidal treatments. Amitrole (3-amino-s-triazole) at 1.1 kg ai/ha and picloram (4-amino-3,5,6-trichloropicolinic acid) at 0.6 kg ai/ha reduced stands of common milkweed (Asclepias syriaca L.) for a 4-yr period. Glyphosate [N-(phosphonomethyl)glycine] at 2.2 kg ai/ha reduced stands of milkweed for two to three growing seasons. Glyphosate or amitrole applied in June (early bud stage) more effectively reduced milkweed stands in the second year than did the herbicides when applied in August (post-flowering stage). Treatments of 2,4-D [(2,4-dichlorophenoxy)acetic acid], 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid], and dicamba (3,6-dichloro-o-anisic acid) did not reduce stands of common milkweed.

Strong regeneration ability from rhizome fragments in two invasive clonal plants (Solidago canadensis and S. gigantea)

“…Seasonality, which has not been taken into account in this study, is another. Time of year may be crucial because the nutrient content of rhizomes varies within the growing season in other species (Harris and Davy 1986;Bhowmik 1994). In an experiment with torpedograss (Panicum repens), planting month had a strong effect on shoot growth rate and biomass allocation (Hossain et al 2001).…”

“…The importance of spread by clonal fragments has been demonstrated for many plant species (e.g. Bhowmik 1994;Cordazzo and Davy 1999;Dietz et al 2002;Akamine et al 2007;Pan et al 2009), and is especially important for invasive plant species penetrating into natural or near natural environments (e.g. Puetz 1994;Hollingsworth and Bailey 2000;Dong et al 2010).…”

Field deposition of Bt transgenic corn pollen: lethal effects on the monarch butterfly

“…from early June to mid September (Urquhart 1960;Borkin 1982). Milkweed is commonly found in corn fields and adjacent non-cultivated habitats where it is a food plant for monarch larvae (Cramer and Burnside 1982;Bhowmik 1994;Yenish et al 1997;Hartzler and Buhler 2000;L.C. Hansen, unpublished data).…”

Effects of Corn Plants and Corn Pollen on Monarch Butterfly (Lepidoptera: Danaidae) Oviposition Behavior

“…The monarch butterßy, Danaus plexippus (L.), is of particular interest because it is a specialist on milkweed (Asclepiadaceae), a secondary succession plant that frequently occurs in and around the edges of cornÞelds (Yenish et al 1997;Bhowmik 1994). Recent work shows that monarch larvae fed leaves of Asclepias curassavica L. dusted with Bt-corn pollen suffered higher mortality than larvae reared on leaves with untransformed corn pollen or leaves without pollen (Losey et al 1999, Jesse andObrycki 2000).…”