Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 6/19/2016
Publication Date: 6/19/2016
Citation: Price, A.J., Duzy, L.M., Balkcom, K.S., Kornecki, T.S. 2016. Glyphosate resistant weeds - a threat to conservation agriculture [abstract]. 7th International Weed Science Conference.
Technical Abstract: Glyphosate-resistant weeds are now present throughout the Southeast. Hundreds of thousands of conservation tillage cotton acres, some currently under USDA Natural Resources Conservation Service (NRCS) conservation program contracts, are at risk of being converted to higher-intensity tillage systems. The shift to higher-intensity tillage facilitates burial of small weed seed as well as use of preplant incorporated herbicides for control of problematic weeds, especially in dry-land cotton production. NRCS defines conservation agriculture as cropping systems that maintain a minimum 30% residue on the soil surface. Recent NRCS programs such as EQIP, the Conservation Security Program and the recently enacted 2008 Farm Bill Conservation Stewardship Program offer incentive contracts rewarding conservation. Cropping systems with higher resource conservation receive higher payments; in many states, use of high residue cover crops increase payments. Despite definite advantages over traditional tillage practices, conservation tillage adoption remained sluggish through the 80’s and mid 90’s due, in large part, to unreliable weed control options in conservation tillage systems. Subsequently use of the broad-spectrum herbicide, glyphosate, in conjunction with glyphosate-resistant cultivars offered a successful alternative to conventional weed management that could be incorporated into conservation agriculture systems. Best management practices recommend rotating crops and chemicals to avoid the development of resistance in weeds, insects, and diseases. Unfortunately many producers have had little economic opportunity to grow different crops for a number of reasons. In addition, the system of glyphosate-resistant crops has become so prevalent that rotation of crops does not ensure that chemical weed control choice will change when crops are changed. Currently, glyphosate resistant Palmer amaranth is common throughout the Mid-South and Southeastern US and use of intensive tillage is increasingly common threatening gains in soil conservation.