2005 Peanut Weed Control Update Eric P Prostko

2005 Peanut Weed Control Update Eric P. Prostko Extension Weed Specialist Department of Crop & Soil Sciences The University of Georgia Tifton

Strip-Tillage Peanuts • 2, 4 -D in Feb or March? • Burndown 3 -4 weeks before planting • Prowl Management – Rate – Time of application – EC vs H 20 • Clean seedbed at planting • Plan on using Poast or Select later on • Could use Valor

Weeds Sprayed Day of Planting Weeds Sprayed 2 Weeks Before Planting

Crabgrass Control (%) with Prowl EC vs. Prowl H 20 in Dryland, Strip-Till Cotton, 2004 a a Ratings obtained 9 WAP 1 st rainfall event did not occur until 12 DAP (1”) 6 replications (10 rows x 75’) a a Prowl 3. 3 EC @ 2. 4 pts/A Prowl H 20 3 ACS @ 2. 1 pts/A

% control Florida Pusley Control with Prowl in Strip Tillage – 24 DAP LSD 0. 05= 25, nontreated check = 0%

Can I put Prowl over-the-top of a newly emerged peanut? • Not a good idea for cotton and soybean – Label specifically prohibits POST applications on these crops • Overhead irrigation supplemental peanut label – at planting or up to 2 days after planting and before crop emergence • No data on peanut as far as I know • 2004 Research

POST Applied Prowl Injury on Peanut

Peanut Yield (DP-1) Response to Prowl Application Timings Averaged over two formulations (Prowl and Prowl H 2 O applied at 1. 00 lb ai/A) P = 0. 198

Peanut Yield (DP-1) Response to Prowl Formulations (1. 00 lb ai/A) (2. 1 pt/A) Averaged over five application timings (2. 4 pt/A) P = 0. 0541 LSD 0. 10 =86

Pigweed Problems - 2004

Why Palmer Amaranth? • grows faster than other pigweeds • more competitive than other pigweeds • prolific seed producer – 1, 000 seeds/plant – 9 -12 WAE – 2 generations/year • herbicide tolerance

Peanut/Pigweed Herbicides • residual herbicides – DNA’s, Strongarm, Valor, Dual (or generics), Outlook – Incorporation methods • postemergence – GMAX + Storm, Cadre, Pursuit, Blazer, Cobra, Storm – Timing, timing

Grady County, GA (2004)

TSW in Georgia Confirmed in 29 counties by GA Dept. of Ag and UGA

TSW Control in Peanut • plant in twin rows • Gramoxone Max + Dual Magnum + Basagran or Storm – EPOST • Cadre, Pursuit, Strongarm* - POST – Could add more Dual here *24 c label for POST applications of Strongarm in 2005 (GA only)

Strongarm - POST • 24 c label in GA • tropical spiderwort – 1 -2 leaf stage • 0. 45 ozs/A + NIS • from cracking up until 30 DAP • 18 month cotton/corn rotation

POST Strongarm Injury - 5 DAT 0. 45 ozs/A Applied 28 DAP Air Temp - 780 RH - 86% % Cloud Cover - 20

Metolachlor Mysteries? • 9 formulations in marketplace • new metolachlors (88% s + 12% r) – Dual Magnum, Dual II Magnum (Syngenta) – Cinch (Du. Pont) • old metolachlors (50% s + 50% r) – Stalwart, Stalwart C (Sipcam) – Me-Too-Lachlor, Me-Too-Lachlor II (Drexel) – Parallel PCS, Parallel (Makhteshim-Agan)

Metolachlor Prices *only labeled for use in field corn and popcorn

Tropical Spiderwort Response to Dual Magnum and Stalwart, Grady Co. , 2004 - I * Applied PRE at 1 pt/A.

Tropical Spiderwort Response to Dual Magnum and Stalwart, Grady Co. , 2004 - II * Applied POST at 1 pt/A with glyphosate to 3” tall COMBE.

For More Information About Spiderwort UGA Extension Circular #884 • Identification and Control of Tropical Spiderwort in Georgia Field Crops • www. gaweed. com •

What’s wrong with my Cadre?

PE-09 -04 August 3, 2004 60 DAT Cadre in 2004 Untreated Cadre @ 1. 44 ozs/A Agrioil @ 1% v/v Applied 24 DAP

PE-10 -04 August 4, 2004 55 DAT Cadre in 2004 Untreated Cadre @ 1. 44 ozs/A Agrioil @ 1% v/v Applied 27 DAP

Cadre in 2004 Untreated PE-16 -04 August 3, 2004 Gramoxone Max @ 5. 5 ozs/A + Basagran @ 8 ozs/A (14 DAP) fb Cadre @ 1. 44 ozs/A + 80/20 @ 0. 25% v/v (29 DAP)

Valor in Peanuts - The Bottom Line • Injury will occur if heavy rainfall occurs from cracking until ~2 WAC • peanut yield should not be reduced if stand is not lost • except this or do not use it – repeated complaints may jeopardize label! • growers either love it or hate it – Dedicated sprayer? • hose and nozzle clean-out very important!!!!! • Glyphosate was developed as an industrial cleaner!!

Reduced Rates of Valor Good or Bad idea? • May reduce injury potential some but • Length of FL beggarweed control may be compromised • Use of less than 3 ozs/A for beggarweed is below labeled rate thus Valent is not liable

Florida Beggarweed Control With Valor (> 56 DAT) Source: Valent

Cowpea Control in Peanut - 2004 • 12 treatments • PRE - Spartan, Valor, Strongarm • POST - Gramoxone, Blazer, Storm, Cobra, Classic • All provided some control early but…. . • < 70% at 56 DAP – Gramoxone Max (8 ozs/A) - 60% – Classic (0. 5 ozs/A) 65%

Spartan in Peanut • • • Labeled in 2004 4 F formulation 4. 8 to 8. 0 ozs/A soil-applied broadleaf weed control nutsedge cotton rotation concerns crop injury on lighter soils PPO inhibitor

Spartan Rotation Restrictions

Spartan Injury

Cobra in Peanut • Labeled in late Fall 2004 • postemergence – 6 leaf peanut – 90 day PHI • 12. 5 ozs/A • broadleaf weed control – croton, copperleaf, ragweed, poinsettia, pigweed • a hotter Blazer • tank-mixes with Basagran, Cadre, Pursuit, Select, 2, 4 DB

www. gaweed. com