The effects of annual, aerial and ground, herbicide treatments with glyphosate and metsulfuron were evaluated for control of Old World climbing fern (OWCF) and effects on native plants on tree islands in Arthur R. Marshall Loxahatchee National Wildlife Refuge during 2006 to 2009. Initial aerial herbicide treatments reduced OWCF cover by greater than 98% on metsulfuron-treated islands and greater than 88% on glyphosate-treated islands, but there was a concomitant decrease in native ground cover with both herbicides. Follow-up ground treatments, during years two and three of the study, were effective at maintaining low levels of OWCF. OWCF cover at the end of the study was 1 to 2% of pretreatment cover on metsulfuron-treated islands and 8 to 10% on glyphosate-treated islands. At the end of the study (3 yr after treatment), species richness was dominated by ruderal native species not typically found on tree islands. The survival rate of tree and shrubs was 65 to 93% on islands treated with metsulfuron and 6 to 20% on islands treated with glyphosate. Minimum effects were recorded for canopy cover on tree islands treated with metsulfuron compared with glyphosate. These data indicate that the aerial application of metsulfuron can be used for control of OWCF on tree islands. Follow-up ground treatments will be required for OWCF regrowth and new sporelings and should be conducted within 1 yr of the aerial application.

Field experiments were conducted from 2007 through 2009 at four locations in Missouri to evaluate the effect of May and August herbicide applications on weed control, total biomass yield, and forage nutritive values. Experiments were conducted in established tall fescue pastures that contained natural infestations of common ragweed and tall ironweed. Treatments consisted of 2,4-D, metsulfuron, aminopyralid, 2,4-D + dicamba, 2,4-D + picloram, aminopyralid + 2,4-D, and 2,4-D + dicamba + metsulfuron. All herbicide treatments provided > 76% control of common ragweed 1 mo after treatment (MAT), except metsulfuron alone which provided ≤ 62% control. August applications provided greater reductions in common ragweed density than May applications the following spring. Few differences in tall ironweed density were observed, but metsulfuron-containing herbicides tended to provide the lowest reduction in tall ironweed stem density the following spring. Biomass yields were generally greater in nontreated compared to herbicide-treated plots. Crude protein (CP) concentration and relative feed value (RFV) were higher in nontreated compared with herbicide-treated biomass. Overall, the poorer nutritive values and lower biomass yields in the herbicide-treated compared with the nontreated biomass may be partially explained by the removal of common ragweed, tall ironweed, and legumes with the herbicide treatments. Pure samples of common ragweed and white clover were greater in nutritive values than pure samples of tall fescue at all June harvests. Results indicate that common ragweed offers nutritive values equivalent to or greater than tall fescue and white clover when harvested in June at the vegetative stage of growth and that the removal of common ragweed and tall ironweed with herbicide applications is not likely to improve forage nutritive values of the total harvested biomass of tall fescue pastures, at least by the season after treatment.