1 / 22

The current state of herbicidal weed control

The current state of herbicidal weed control. Micheal D. K. Owen Iowa State University Ames, IA 50011 USA mdowen@iastate.edu www.weeds.iastate.edu. Introduction. Glyphosate-based weed control systems predominate in soybeans and are increasing in corn

willis
Download Presentation

The current state of herbicidal weed control

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. The current state of herbicidal weed control Micheal D. K. Owen Iowa State UniversityAmes, IA 50011 USA mdowen@iastate.edu www.weeds.iastate.edu

  2. Introduction • Glyphosate-based weed control systems predominate in soybeans and are increasing in corn • The benefits of glyphosate are intuitively obvious • Pseudo-benefits of glyphosate-based systems reflect incorrect assumptions by growers (i.e. simplicity and cost compared to “conventional” systems) • Risks of glyphosate-based systems are no different than with other herbicide systems • Selection pressure imposed on weed communities resulting in evolved resistant populations or weed population shifts • Application timeliness • What alternatives exist?

  3. Grower perception is the problem • Recent survey conducted by Dr. Bill Johnson (Purdue University) quantifies the extent of the problem (see www.weeds.iastate.edu) • 90% of soybeans and 30+% of corn are RR® varieties/hybrids • Multiple applications of glyphosate yearly imposes selection pressure on weeds resulting in evolved resistance or weed population shifts • Growers (~66%) indicate they are not concerned about changes (current or future) in weeds attributable to glyphosate selection pressure • new herbicides will be available soon • Problem does not exist if it is not on my farm • WRONG!!!

  4. Glyphosate stewardship • Glyphosate stewardship should be a key consideration in order to preserve the utility of the technology • Continuing misperceptions about simplicity of glyphosate • Flexibility of application timing provides a false sense of security • Ability to control larger weeds results in treatment after weeds have reduced potential yield • Increased adoption in corn will result in greater selection pressure resulting in “new” weed management issues • Evolution of glyphosate resistant weeds continues to escalate

  5. Glyphosate Stewardship: pollen drift provides a new management “opportunity”

  6. Glyphosate stewardship • Clean fields do not necessarily equate to good weed management • The objective of weed management is to protect crop yield potential • Diversified weed management tactics provide significant benefits to glyphosate-based systems • Residual herbicides applied EPP or PRE are important components of a corn and soybean weed management program • Mechanical weed control tactics should be included • Timely application of tactics is critical for all weed management programs

  7. Role of Pre-emergent Herbicides inRR (LL, etc.) Systems • Broaden spectrum of control • Improve consistency • Protect yields • Widen application window • Reduce selection pressure

  8. 2005 Critical Period Studies • Three pre treatment • Control • Corn: 0.6 or 1.2 qt Harness Xtra 6.0 • Soybean: 1 or 2 qt INTRRO • Four post timings • Control • V2 • V4 • V6

  9. Effect of preemergence Harness Xtra 6.0 and INTRRO in weed density at V6 application Harness Xtra: Low = 0.6 qt, High = 1.2 qt INTRRO: Low = 1 qt, High = 2 qt

  10. 2 qt INTRRO Relationship Between Weed Biomassand Soybean Yield Loss Control Data include three preemergence herbicide treatments.

  11. Weed Growth Rate vsYield Loss Rate

  12. New products • A dearth of “opportunities” • This represents a partial list of that which is “new” • Many “new” companies taking an increasingly active role in re-introducing old products or marketing generic versions of existing herbicides • In corn and soybeans, still some discovery activity by the major companies • No “silver bullets” in the foreseeable future (if ever there was a “silver bullet” – see workshop 9)

  13. Milestone (aminopyralid) • Pastures, CRP, non-crop • Growth regulator – pyridine family • Particularly strong on composites (thistles) • No grazing restrictions (3 day flush out) • Non-volatile

  14. Milestone

  15. Impact 2.8SC(topramezone) • Postemergence in field corn, seed corn, popcorn and sweet corn • HPPD inhibitor (bleacher) • Broadleaf (3-8”) and grass (3-4”) • 0.75 fl oz/A (0.02 lb ai/A) • MSO or COC +UAN • 0.25 to 1.0 lb atrazine recommended

  16. Impact 2.8SC • One application per year • 45 day harvest restriction • Do not tank mix or use sequential application with isoxaflutole (Balance, etc.) or mesotrione (Callisto, etc.) • Rotation restrictions • Soybean: North of I-80 18 months South of I-80 9 months • 2EE label: North of I-80 (Except N of 20 and west of US71) 0.5 oz rate allows 9 month soybean replant

  17. Resolve(rimsulfuron) • Component of Steadfast (rim + nicosulfuron) • Current label: • Postemergence up to 12” or V6, whichever is most restrictive • PRE label newly available • 1 oz Resolve = 0.25 oz rimsulfuron • 0.75 oz Steadfast = 0.19 oz rimsulfuron • Half-life: 2-4 days

  18. ET Herbicide/Defoliant • Likely to be introduced in the Midwest by Ninchino America, Inc. • A PPO inhibitor to be positioned as an addition to glyphosate in corn • Registered in cotton as a defoliant • Inexpensive control of small seeded annual broadleaf weeds (e.g. common waterhemp and common lambsquarters) • Injury (cosmetic) to corn a factor

  19. Imperium • Pre-mix of EPTC plus acetochlor re-introduced by Gowan Company • Previously marketed as Doubleplay • Requires incorporation • Effective on difficult annual grasses (i.e. woolly cupgrass)

  20. KIH-485 60WG • New chemistry! • Under development by K-I Chemical USA, Inc. • ISU has 4 years experience with the product • Investigations in field corn, popcorn, soybeans • EPP, PRE, Fall • Chemistry not released but comparisons made to other chloracetamide products (i.e. Dual MAGNUM) • Broad spectrum control • Woolly cupgrass • Shattercane • Small-seeded annuals • Velvetleaf • Excellent residual activity, very low a.i./acre

  21. Other Products/Changes • Radius (Bayer) flufenacet + isoxaflutole • Significantly higher ratio of fluf:isox than in Epic • Callisto: now cleared for pre and post applications on sweet corn • Select Max: no additives required with ‘loaded’ glyphosate; greater adjuvant flexibility with other posts; 1 lb/gal EC rather than 2 lb/gal • Boundary: changed from 7.8EC to 6.5EC • Propel (Rosens): new brand of dimethenamid-P

  22. Questions?

More Related