Cotton and Palmer Amaranth (AMAPA) Response to Milo-Pro Applied at-Plant and POST Lynn M. Sosnoskie and A. Stanley Culpepper UGA, Tifton, GA Jared Whitaker UGA, Statesboro, GA Jeremy M. Kichler UGA, Oglethorpe, GA Alan C. York NCSU, Raleigh, NC

AMAPA is large, competitive, C4 annual that can form dense populations in infested fields, reducing yields and harvest efficiency

Cotton is particularly susceptible to weed interference Planted at lower densities than other crops Requires higher temperatures for rapid growth Uncompetitive crop canopy

1X Weathermax + 1X Staple LX at 5 WAT

1/2 inch in 12 hr 4 inches 52 hr

Residual Herbicide use is needed for the management of AMAPA in cotton Milo-Pro TM –Propazine –PSII electron transport inhibitor –PRE and POST for grain sorghum –0.75 to 1.2 qts/A for sandy loam to clay loam soils –Not recommended for sands or loamy sands –Cotton does have some tolerance to propazine Abernathy et al Agron. J. Kendig et al PHP

Locations Macon County, GA and Moultrie, GA Sutton’s Field and Southern Ag Expo Sandy loam Planted 28 May, 2009 (Macon) Planted 14 May, 2009 (Moultrie) 6’ x 25’ plots, 36” row spacing DP 0949 B2RF Herbicide treatments replicated 3X in RCBD Herbicides applied at application volume of 14.8 Gal/A with CO 2 backpack sprayer and flat fan nozzles Crop injury GLY-R AMAPA control at Macon County site

Macon County and Moultrie, GA TRTPREPOST1POST2 (2-3 Leaf)(6-8 Leaf) 1none 2 Milo-Pro 1 pt/A WMAX 3 Milo-Pro 2 pt/A WMAX 4 Cotoran 2 pt/A WMAX 5noneWMAX 6none Milo-Pro 1 pt/A WMAX 7none Milo-Pro 2 pt/A WMAX 8none Parrlay 1.3 pt/A WMAX 9none Staple 2.5 oz/A WMAX 10 Reflex 1 pt/A WMAX 11 Reflex 1 pt/A Milo-Pro 2 pt/A WMAX 12 Reflex 1 pt/A Milo-Pro 1 pt/A WMAX Milo-Pro 1 pt/A WMAX

Locations Rocky Mount, NC (2 sites) Upper Coastal Plain Research Station Sandy loam Planted 6 and 13 May, ’ x 30’ plots, 36” row spacing DP 0924 B2RF Herbicide treatments replicated 4X in RCBD Herbicides applied at application volume of 14.8 Gal/A with CO 2 backpack sprayer and flat fan nozzles Crop injury

Rocky Mount, NC TRTPREPOST1POST2 (2-3 Leaf)(6-8 Leaf) 1none 2 Milo-Pro 1 pt/A PMAX 3 Milo-Pro 2 pt/A PMAX 4 Cotoran 2 pt/A PMAX 5nonePMAX 6none Milo-Pro 1 pt/A PMAX 7none Milo-Pro 2 pt/A PMAX 8none Parrlay 1.3 pt/A PMAX 9none Staple 2.5 oz/A PMAX

Cotton Injury

Cotton Injury - At Plant Application Data averaged across Macon County and Moultrie, GA, sites 1 WA-PRE3 WA-PRE No Pre0% Milo-Pro 1 or 2 pt/A 0% Cotoran 2 pt/A 0% Reflex 1 pt/A 11%5%

Reflex Injury at 1pt/A PRE

Cotton Injury – POST Application to 2-3 Leaf Cotton Data averaged across Macon County and Moultrie, GA, sites 1 WA-POST13 WA-POST1 Weathermax 22 oz/A 0% Milo-Pro + Weathermax 1 pt/A + 22 oz/A 0% Milo-Pro + Weathermax 2 pt/A + 22 oz/A 3%0% Parrlay + Weathermax 1.33 pt/A + 22 oz/A 5%0% Staple + Weathermax 2.5 oz/A + 22 oz/A 10%0%

Milo-Pro 2 pt/A plus Roundup POST 1 WA-POST1 Application to 2-3 leaf cotton

Rocky Mount, NC Some Milo-Pro PRE injury, especially at higher rate, but no more than 10% in any one plot; mean injury was not >6% and was transient

Rocky Mount, NC Some Milo-Pro POST injury, especially at higher rate, but no more than 10% in any one plot; mean injury was not >8% and was transient

GLY-R AMAPA Control

GLY-R AMAPA Control - At Plant Application Macon County, GA 1 WA-PRE3 WA-PRE No Pre0% Milo-Pro 1 or 2 pt/A 99%85-96% Cotoran 2 pt/A 98%82% Reflex 1 pt/A 99%

GLY-R AMAPA Control – POST1 Application Macon County, GA 1 WA-POST13 WA-POST1 No PRE Parrlay POST1 0% No PRE Milo-Pro (1 pt) POST1 0%7% No PRE Milo-Pro (2 pt) POST1 60%47% No PRE Staple POST1 95%77% All treatments received Weathermax at 22 oz/A at POST1

GLY-R AMAPA Control – All POST Applications Macon County, GA 1 WA-POST22 WA-POST21 WA-POST33 WA-POST3 Reflex PRE 84%75%77%67% Reflex PRE Milo-Pro (1 pt/A) POST1 Milo-Pro (1 pt/A) POST2 97%94%93% Reflex PRE Milo-Pro (2 pt/A) POST1 97%85%88% All treatments received Weathermax at 22 oz/A at POST1 and POST2 All treatments received Direx and MSMA at Layby (POST3)

Reflex PRE fb WMAX fb WMAX fb Direx + MSMA

Reflex PRE fb Milo-Pro (2 pt/A) + WMAX fb WMAX fb Direx + MSMA

Reflex PRE fb Milo-Pro (1 pt/A) + WMAX fb Milo-Pro (1 pt/A) + WMAX fb Direx + MSMA

GLY-R AMAPA Control and Yield Macon County, GA End of season control Yield (lbs seed cotton/A) Reflex PRE 50% 732 Reflex PRE Milo-Pro (1 pt/A) POST1,2 86% 1359 Reflex PRE Milo-Pro (2 pt/A) POST1 78% 1192 All treatments received Weathermax at 22 oz/A POST1 and POST2 All treatments received Direx and MSMA at Layby (POST3)

Cotton Injury and Yield Clayton, NC % Chlorosis 3 WA-PRE % GR 3 WA-PRE Yield (lbs seed cotton/A) No Pre0% 2971 Milo-Pro PRE 2 pt/A 10%13%2577 Milo-Pro PRE 4 pt/A 27%32%2003 Injury ratings of 5 to 7% were observed 1-3 WA-PRE applications of Milo-Pro at 1 pt/A at Attapulgus, GA. No injury was observed 6 WA-PRE. This isn’t different than what was seen at Rocky Mount. Injury ratings of 13 to 32% were observed 1-3 WA-PRE applications of Milo-Pro at 2 pt/A at Attapulgus, GA. Injury was still 33% 3 WA-POST2.

Previous Research Abernathy et al Agron. J. –48 cotton varieties evaluated for resistance to propazine broadcast PRE at 0.56 kg/ha –Sandy loam with OM <1% –Injury ratings ranged from 3-53% Aubun M, Acala B-3080, Paymaster 303 = 3% Coker 5110, Coker 312 = 8% Paymaster 111A, Deltapine SR-2 = 50% Blightmaster A-5 = 53% –Less than 20% was regarded as a tolerant response to propazine

Previous Research Kendig et al Plant Health Progress –DP 5415RR was screened for tolerant to propazine –5 rates: 0, 0.25X, 0.5X, 1X, 2X of 1.12 kg/ha –4 growth stages: PRE, cotyledon, 2-lf, 4-lf –Some injury observed for PRE applications (sandy-loam) but visual injury and weight reductions were greatest from over the top applications made at the cotyledon and 2-lf stages –Injury increased with rate

Summary Milo-Pro applied PRE at 1-2 pts/A injured cotton 0-7% (Attapulgus, Rocky Mount); injury was transient There was no observable injury at Macon County and Moultrie for Milo-Pro applied PRE Higher rates (4 lbs/A), on sandier soils (Attapulgus, Clayton) with adequate rainfall resulted in unacceptable injury ratings due to PRE applications Injury resulting from POST applications of Milo-Pro did not exceed 8%; injury was not greater than what was observed for Staple; injury was transient

Summary Residual herbicides (PRE and POST) are crucial for managing Palmer amaranth Milo-Pro (2 pt/A) and Reflex (1 pt/A) provided 96% and 99% control, respectively at 3 WA-PRE, the timing of the first POST application Milo-Pro was most effective as a POST applied herbicide when following Reflex PRE (residual and topical activity) A single application (2 pt/A POST1) or two applications (1 pt/A POST1 and POST2) of Milo-Pro provided 85% and 94% control, respectively, of GLY-R Palmer 2 WA-POST2 and carried the crop to layby and harvest According to these results, Milo-Pro may be a useful component in an INTEGRATED program to manage GLY-R Palmer amaranth