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United States Department of Agriculture

Agricultural Research Service

Research Project: PROACTIVE MANAGEMENT FOR SUSTAINABLE RANGELAND PRODUCTION Title: Growth Regulator Herbicides Prevent Invasive Annual Grass Seed Production

item Rinella, Matthew
item Haferkamp, Marshall -
item Masters, Robert -
item Muscha, Jennifer
item Bellows, Susan
item Vermeire, Lance

Research conducted cooperatively with:
item Dow Agrosciences, Llc

Submitted to: Invasive Plant Science and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 14, 2009
Publication Date: March 17, 2010
Citation: Rinella, M.J., Haferkamp, M.R., Masters, R.A., Muscha, J.M., Bellows, S.E., Vermeire, L.T. 2010. Growth Regulator Herbicides Prevent Invasive Annual Grass Seed Production. Journal of Invasive Plant Science and Management. 3:12-16.

Interpretive Summary: This research tested a novel approach for controlling invasive annual grasses with growth regulator herbicides such as aminopyralid, picloram and 2,4-D. It has been known for decades that growth regulators can dramatically reduce cereal seed production if applied for broadleaf weed control late in the growing season while cereals are developing reproductive parts. We tested whether or not growth regulators have this same effect on seed production of an invasive annual grass (i.e. Japanese brome). Our results show that growth regulators can dramatically reduce invasive annual grass seed production. Therefore, it may be possible to use growth regulators to control invasive annual grasses by depleting their short-lived seed banks. Growth regulator herbicides are less damaging to desirable perennial grasses than currently used herbicides.

Technical Abstract: Auxinic herbicides, such as 2,4-D and dicamba, that act as plant growth regulators are commonly used for broadleaf weed control in cereal crops (e.g. wheat, barley), grasslands, and non-croplands. If applied at later growth stages, while cereals are developing reproductive parts, the herbicides can reduce seed production. We tested whether growth regulators have this same effect on the invasive annual grass Japanese brome. The herbicides 2,4-D, aminopyralid, dicamba, and picloram were applied at typical field use rates to Japanese brome at various growth stages. In a field study, aminopyralid and picloram reduced seed production more than 95% when applied at the internode elongation, boot or heading stages of growth. Picloram was similarly effective in a greenhouse study, whereas dicamba appeared to be slightly less effective and 2,4-D was much less effective. Our results indicate it should be possible to control Japanese brome by using growth regulator herbicides to reduce its seed production, thereby depleting its short-lived seed bank. Desirable perennial grasses are likely to be fairly resistant to growth regulators, because as opposed to seeds, perennial grasses rely more on vegetative means of reproduction to maintain populations.

Last Modified: 12/1/2015