Summarizing 5 Years of Weed Management Research in Georgia Eric P. Prostko Extension Weed Specialist and Tim L. Grey and William K. Vencill Research Weed Scientists

What have we done? t63 field trials tMajor areas of emphasis è RR corn systems è LL corn systems è Accent vs. Option è harvest-aids è tropical spiderwort In-crop Post-harvest è other new products Aim Callisto, Lexar/Lumax

Should you use the RR corn system? t advantages èInexpensive èeasy èBroad spectrum èReduced drift concerns èNo soil insecticide issues tdisadvantages èNo residual èover-reliance on a single product èHerbicide resistance concerns èVolunteer in other RR crops

Texas Panicum Control At Harvest with Single or Split Applications of Roundup WM - II CN (Attapulgus) Untreated Roundup 22 ozs/A 21 DAP Roundup 22 ozs/A DAP

Corn Yield Response to Single or Split Applications of glyphosate (4.5 lb 22 ozs/A. Average of 6 irrigated locations ( ) DKC67-60RR

Glyphosate Resistance Around the World (8 species) t rigid ryegrass (1996) t goosegrass (1997) t horseweed (2000) t Italian ryegrass (2001) t hairy fleabane (2003) t buckhorn plantain (2003) t common ragweed (2004) t Palmer amaranth (2005) èIn Central Georgia * Can be found in US

2005 GR-Pigweed Survey

Preserving the Value of Glyphosate t tank-mix 2,4-D in burndown when glyphosate will be used in-crop èConsider paraquat if appropriate t Alternate glyphosate use with other herbicide modes of action èTank-mix with atrazine in corn tUse other practices such as cultivation tDo not allow weed escapes to produce seed

Herbicide programs for managing glyphosate and ALS-resistant Palmer amaranth in Georgia field corn.

Texas Panicum Control OR

Accent vs Option Summary Texas Panicum Control t 8 field trials t Accent > Option è9 of 32 comparisons (28% of time) t Option > Accent è1 of 32 comparisons (3% of time) t Accent = Option è22 of 32 comparisons (69% of time) t No statistical differences in corn yield were observed in any trial!

Texas Panicum Control (104 DAT) - II Accent vs Option CN (Attapulgus) Applied 21 DAP PANTE = 1-2”, 2-4 leaf Untreated 0.67 ozs/A 1% v/v 1.5 ozs/A 1.25% v/v 3 lbs/A

Harvest-Aid Research

Harvest-Aid Untreated Roundup 22 oz/A + Aim 1 oz/A + 1% v/v 15 DAT

Tropical spiderwort (a.k.a. Benghal dayflower) Commelina benghalensis ttropical Africa native tannual or perennial tseeds and rhizomes tabove and below ground flowers t1,600 seeds/plant talternate host of southern root-knot nematode tReservoir for southern stem blight (white mold)

TSW in Georgia * confirmed in 29 counties by GA Dept. of Ag and UGA in 2004 (blue) * identified in 4 more counties in 2005 (black)

Tropical Spiderwort Control in Field Corn Untreated (166 bu/A) Aim 1.5 ozs/A Dual Magnum 1.33 pt/A 1% v/v (168 bu/A) 34 DAT $24/A treatment cost (excluding application)

Post-Harvest – Field Corn (Our Achilles heel?)

Post-Harvest – ,4-D (1 pt/A) + Dual Magnum (12 ozs/A) + COC (1% v/v) 22 DAT 43 DAT 54 DAT * * * Grady County $12/A Treatment cost (excluding application)

The Future tLiberty Link? tProducts labeled but not yet tested in GA èImpact (AmVac) èStout (DuPont) tNew products being developed èKIH-485 tPost-harvest for tropical spiderwort tothers??