Weed Control in

Alfalfa

Weeds in Alfalfa

Weed Control in Alfalfa

Established or Seedling Alfalfa?

Type and Severity of Weed Problems

Quality Needs?ProteinTonnage

Alfalfa Establishment

Fall Seeding - erratic rainfall, grasshoppersWeed Problems: cheatgrass, mustards,

volunteer wheat, henbit, field pennycress, etc.

Spring Seeding - intense rainfall, freezeWeed Problems: pigweeds, foxtails, velvetleaf

kochia, crabgrass, etc.

Alfalfa Establishment

Be aware of the potential for herbicide carryover from the previous crop, especially the sulfonylurea herbicides like Glean, Finesse, Amber, Rave, Maverick, Ally, Peak, Spirit, etc.

Alfalfa EstablishmentHerbicide Options

Herbicide Rate Cost (product/acre) ($/acre) Preplant Incorporated: Treflan 1 - 1.5 pt 2.25 - 3.50 Balan DF 2 - 2.5 lb 21.00 - 26.00 Eptam 3.5 - 4.5 pt 16.00 - 20.00Postemergence: Buctril 1 - 1.5 pt 8.50 - 12.50 Butyrac 1 - 3 qt 8.00 - 24.00 Poast Plus 1 - 2.25 pt 6.50 - 14.50 Select 6 - 8 oz 9.50 - 12.65 Pursuit 3 - 6 oz 12.50 - 25.00 Raptor 4 - 6 oz 17.00 - 26.00 Roundup Original Max 22 - 44 oz 6.20 - 12.40

Alfalfa EstablishmentHerbicide Options

Herbicide Rate Cost (product/acre) ($/acre) Preplant Incorporated: Treflan 1 - 1.5 pt 2.25 - 3.50 Balan DF 2 - 2.5 lb 21.00 - 26.00 Eptam 3.5 - 4.5 pt 16.00 - 20.00

Alfalfa EstablishmentHerbicide Options

Herbicide Rate Cost (product/acre) ($/acre) Postemergence: Buctril 1 - 1.5 pt 8.50 - 12.50 Butyrac 1 - 3 qt 8.00 - 24.00 Poast Plus 1 - 2.25 pt 6.50 - 14.50 Select 6 - 8 oz 9.50 - 12.65 Pursuit 3 - 6 oz 12.50 - 25.00 Raptor 4 - 6 oz 17.00 - 26.00 Roundup Original Max 22 - 44 oz 6.20 - 12.40

Weed Control in Fall Seeded Alfalfa at Manhattan, KS. Application Herbicide Rate Time Buwf Cheat Wheat (oz/A) -------------(% )----------- Eptam 4 pt PPI 10 73 13 Treflan 1 pt PPI 0 10 0 Pursuit 1.44 oz FP 100 98 80 Pursuit 1.44 oz SP 80 48 15 Buctril 1 pt FP 99 0 0 Butyrac 2 qt FP 49 0 0 Poast Plus 24 oz FP 0 66 78 Poast Plus 24 oz SP 0 54 73 Select 6 oz FP 0 61 95 Select 6 oz SP 0 58 88 LSD (5%) 12 12 17

Weed control in fall seeded alfalfa, Manhattan, KS, 1999 (Peterson&Regehr, ALF9901).

Application Herbicide Time Rate Wheat Cheat Hebi Buwf (% control) Treflan PPI 1.5 pt 47 63 50 10 Pursuit+NIS+N FP 1.44 oz 53 80 78 99 Raptor+NIS+N FP 4 oz 98 90 78 96 Pursuit+NIS+N SP 1.44 oz 43 50 60 100 Raptor+NIS+N SP 5 oz 93 82 60 99 LSD (5%) 16 9 13 12

Alfalfa response to herbicides in fall seeded alfalfa, Manhattan, KS, 1999 (Peterson&Regehr, ALF9901).

Application Alfalfa Total Herbicide Time Rate Injury Yield Forage (%) (lb/A) (lb/A) Treflan PPI 1.5 pt 12 901 7535 Pursuit+NIS+N FP 1.44 oz 0 2707 3392 Raptor+NIS+N FP 4 oz 0 3038 3281 Pursuit+NIS+N SP 1.44 oz 0 1585 3524 Raptor+NIS+N SP 5 oz 0 2351 2633 LSD (5%) 774 1390

Weed Control in Spring-Seeded Alfalfa at Manhattan, KS.

Application Alfalfa Large Palmer Herbicide Rate Time injury crabgrass pigweed (oz/A) -------------(% )----------- Eptam 4 pt PPI 31 99 64 Balan 3 qt PPI 35 96 74 Treflan 1.5 pt PPI 54 98 83 Pursuit 1.44 oz P 0 85 97 Buctril 1 pt P 0 0 69 Butyrac 2 qt P 0 0 77 Poast Plus 24 oz P 0 98 0 LSD (5%) 2 8 10

Weeds Control in Established Alfalfa

Established Alfalfa

Weed ProblemsWinter annuals: cheatgrasses, mustards,

henbit, pennycress, etc.Summer annuals: crabgrass, foxtails,

pigweedsPerennials: johnsongrass, bindweed,

curly dockHerbicide Treatments

Dormant SeasonPostemergence

Estabished AlfalfaTillage

Dormant season tillage may damage crowns and predispose alfalfa to diseases in wetter environments, but light tillage has been used in central and western Kansas to control winter annual weeds without any apparent long-term damage to alfalfa.

Established AlfalfaIrrigation Management

Irrigate alfalfa 5 to 6 days before and after alfalfa mowing. Avoid irrigation immediately after alfalfa is harvested.

Established Alfalfa Herbicide Options

Herbicide Rate Cost (product/acre) ($/acre) Dormant Season Treatments: Karmex 1 - 3 lb 4.30 - 12.90 Velpar 1 - 6 pt 7.75 - 46.00 Velpar Alfamax 1.4 - 4.25 lb 15.40 - 46.75 Sencor 0.5 - 1.33 lb 11.00 - 29.00 Sinbar 0.5 - 1 lb 16.30 - 32.60 Prowl H2O 2 - 8 pt 8.00 - 32.00 Treflan* 2 qt 9.00 Pursuit 3 - 6 oz 2.50 - 25.00 Gramoxone Inteon 2 - 3 pt 7.50 - 11.25* Also may be applied between cuttings during the growing season, but needs to be applied preemergence to weeds.

Established Alfalfa Herbicide Options

Herbicide Rate Cost (product/acre) ($/acre) Postemergence Treatments: Butyrac 1 - 3 qt 8.00 - 24.00 Poast Plus 1 - 2.25 pt 6.50 - 14.50 Select 6 – 8 oz 9.50 - 15.00 Pursuit 3 - 6 oz 12.50 - 25.00 Raptor 4 - 6 oz 17.00 - 26.00 Gramoxone Inteon 16 oz 3.50 Roundup Original Max 22 oz 6.20

Prowl H20Recently approved for use as a dormant season treatment in established alfalfa Rates: 2 to 8 pt/ATiming: After last cutting in fall until 6 inches of

alfalfa regrowth in springProvides preemergence control of certain annual grass and broadleaf weeds. Do not apply less than 50 days prior to alfalfa harvest.Not labeled for use in alfalfa establishment

Velpar AlfaMaxCo-pack from Dupont containing Velpar and Karmexfor dormant season application in alfalfa14.2 lb co-pack contains 5 lb ai Velpar and 6 lb aiKarmexApplication rate: 1.4 to 4.25 lb/A

(10 – 3.3 acres per unit pack)1.4 lb Velpar AM = 1 qt Velpar + ¾ lb Karmex

Controls winter annual grass and broadleaf weeds and early season summer annual weeds.

Velpar AlfaMax GoldPre-mix from Dupont containing 23.1% hexazinone(Velpar) and 55.4% diuron (Karmex) for use as a dormant season treatment in alfalfa. Rate: 1 to 4.3 lb/A

2.2 lb = 1 qt Velpar + 1.6 lb KarmexControls winter annual grass and broadleaf weeds and early season summer annual weeds.Do not replant any crop other than corn (12 mo.) for 2 years after treatment.

Dormant Season Treatments in Established Alfalfa at Ottawa, KS, 1992 (Peterson, Duncan, & Seyfert).

Downy Flix- Herbicide Rate Brome Weed Henbit Pigweed -------------------(% control)----------------- Treflan (Inc.) 2 qt 24 0 80 93 Karmex 1 lb 47 90 58 60 Karmex 2 lb 63 100 100 89 Velpar 1 qt 100 100 100 37 Sencor 0.5 lb 98 100 100 1 Sinbar 0.5 100 100 100 40 Pursuit 1.44 oz 47 100 70 97 LSD (5%) 12 5 13 20

Dormant Season Treatments in Established Alfalfa at Ottawa, KS, 1993 (Peterson, Duncan, & Seyfert). Shepherds- Downy Forage Alfalfa Herbicide Rate purse brome Yield* Yield* (% control) (Tons/A) Treflan 10G 20 lb 0 12 1.64 0.82 Karmex 2 lb 100 47 1.71 0.69 Velpar 1 qt 98 80 1.21 1.01 Velpar 2 qt 100 100 1.32 1.32 Sencor 0.5 lb 94 67 1.74 0.68 Sencor 1 lb 100 91 1.28 1.13 Sinbar 0.5 lb 100 67 1.51 0.94 Sinbar 1 lb 100 96 1.41 1.40 No Treatment 0 0 1.81 0.73 LSD (5%) 8 15 0.35 0.28 * Yields are first cutting only.

Weed control with dormant treatments in established alfalfa, Manhattan, KS, 2004 (P&R, ALF200401). Application Treatment Time Rate Hebi Fipc Tamu Dobr (% control) Karmex DOR 1 lb 70 53 93 10 Karmex DOR 2 lb 98 93 100 33 Velpar DOR 1 pt 90 100 100 82 Velpar DOR 2 pt 100 100 100 98 Karmex+Velpar DOR 1lb+1pt 99 100 100 87 Sencor DOR 8 oz 100 97 30 80 Karmex+Sencor DOR 1lb+8oz 100 100 100 90 Sencor DOR 12 oz 100 100 70 96 Pursuit+NIS+N DOR 4 oz 72 90 90 40 Raptor+NIS+N DOR 4 oz 83 92 92 93 LSD (5%) 7 14 5 14

Velpar – 1 qt/A

Velpar – 2 qt/A

Sencor – 8 oz/A

Karmex – 2lb/A

Raptor – 4 oz/A

Pursuit – 4 oz/A

Chlorosis from Late Dormant Treatment

Downy Brome Control

Approved in summer of 2005Key benefits

o Excellent tolerance to glyphosateo Control of many weed specieso Flexibility in application timeo Environmentally friendly chemistryo Positive impact on yield and quality

Drawbackso Technology seed cost ~ $2.50/lbo No residual weed controlo Limited seed supplies initially

control

sprayed

unsprayed

Roundup Ready Alfalfa

Seed quantities limited initially.

Rate: Up to 44 oz/A Roundup Original Max or WeatherMax in a single application, not to exceed a total 132 oz/A for in-crop treatments per year .

Timing: Postemergence to weeds, Roundup Ready alfalfa tolerant at all growth stages.

Add AMS at 8.5 to 17 lb/100 gallons of spray solution.

Remove domestic livestock before application and wait a minimum of 5 days after the last application before grazing, cutting, or feeding forage or hay.

Non-tolerantControlRR alfalfa

Roundup - 3 x (1 gallon / Acre)

Weed control in fall seeded Roundup Ready alfalfa, Manhattan, KS, 2003 (P&R, ALF200301). Application Treatment Time Rate Wheat Cheat Hebi Buwf (% control) RU Max+AMS FP 26 oz 96 94 80 96 RU Max+AMS FP 52 oz 98 94 89 99 RU Max+AMS SP 26 oz 100 100 40 100 RU Max+AMS SP 52 oz 100 100 50 100 Pursuit+NIS+N FP 1.44 oz 50 100 100 100 Raptor+NIS+N FP 5 oz 98 100 100 100 Pursuit+NIS+N SP 1.44 oz 85 80 35 99 Raptor+NIS+N SP 5 oz 100 100 38 97 LSD (5%) 7 6 6 7

Roundup Ultra Max26 oz

Fall Postemergence

Roundup Ultra Max26 oz/A

Spring Postemergence

Weed control in spring seeded Roundup Ready alfalfa, Manhattan, KS, 2005 (P&R, ALF200501). Application Large Crabgrass Green Foxtail Treatment Stage Rate 6/10 7/6 6/10 7/6 (% control) RU WeatherMax 3 Trif 44 oz 100 86 100 93 RU WeatherMax 8 Trif 44 oz - 100 - 100 RU WM/RU WM 3/8 Trif 22/22 oz 100 100 100 100 Pursuit 3 Trif 4 oz 60 83 71 76 Raptor 3 Trif 4 oz 71 86 76 78 Buctril+Select 3 Trif 16+8 oz 94 95 96 94 LSD (5%) 4 6 4 3

Weed control in spring seeded Roundup Ready alfalfa, Manhattan, KS, 2005 (P&R, ALF200501).

Application Velvetleaf P. Amaranth Treatment Stage Rate 6/10 7/6 6/10 7/6 (% control) RU WeatherMax 3 Trif 44 oz 97 94 100 95 RU WeatherMax 8 Trif 44 oz - 95 100 RU WM/RU WM 3/8 Trif 22/22 oz 95 100 100 100 Pursuit 3 Trif 4 oz 89 90 63 55 Raptor 3 Trif 4 oz 92 90 64 50 Buctril+Select 3 Trif 16+8 oz 80 79 53 58 4 8 14 10 LSD (5%)

Alfalfa yields and stands in spring seeded Roundup Ready alfalfa, Manhattan, KS, 2005 (P&R, ALF200501).

Application Forage Yield Alfalfa Treatment Stage Rate 1st Ct 2nd Ct 2nd Ct St. Red. ----(lb dry wt/acre)---- (%) RU WeatherMax 3 Trif 44 oz 1210 1525 1007 0 RU WeatherMax 8 Trif 44 oz 1573 1113 1080 0 RU WM/RU WM 3/8 Trif 22/22 oz 1609 1113 1107 0 Pursuit 3 Trif 4 oz 1179 1573 960 1 Raptor 3 Trif 4 oz 1273 1525 1050 6 Buctril+Select 3 Trif 16+8 oz 1150 1355 845 11 Untreated 3371 895 501 48 LSD (5%) 850 460 244 10

Roundup Original Max

Effect of early weed control on second cutting alfalfa growth and stands.

K STATEResearch and Extension