Weed Control Update for Wheat Managing Ryegrass Managing

Weed Control Update for Wheat Managing Ryegrass

Managing Ryegrass in Wheat • Currently available: Finesse Hoelon Sencor Axiom • In development: Mesosulfuron

Rates of Hoelon POST on wheat and barley Ryegrass size pt Hoelon 1 - to 3 -leaf 1. 33 pt 3 - to 4 -leaf 1. 33 to 2 pt 5 -leaf to 2 tiller 2 to 2. 67 pt

Timing Hoelon POST Wheat: Before first node (jointing) of wheat

Use of adjuvants with Hoelon POST: Wheat: Can add 1 to 2 pt/acre COC. Suggested only on large grass or dry conditions. Will increase risk of injury. Do not add if cool and wet. Do not use silicones or MSO.

Precautions on Hoelon label: Do not apply if one or more conditions exist: Cold temperature: Anytime during 72 hr preceding application temperature drops below 35 degrees Delay application if freezing temperature predicted within 3 days of application Soil moisture: Moisture at or above field capacity

Tank mixing Hoelon with other herbicides: Don’t do it; will lead to antagonism.

Sequential applications of Hoelon and broadleaf herbicides: Do not apply 2, 4 -D within 5 days of Hoelon application

Hoelon Tank Mixes in Wheat u Label: may tank mix with liquid nitrogen fertilizer (28 to 32%) if the timing for use is compatible u UGA recommends no herbicide tank 1) often to late to control weeds 2) injury potential increased 3) reduced control of ryegrass

Hoelon-resistant Ryegrass Estimated percentage in GA: ? ? ? ?

Alternatives to Hoelon • Currently available: Finesse Hoelon Sencor Axiom • In development: Mesosulfuron

Using Sencor in Wheat u Metribuzin-tolerant cultivar Agri. Pro Mason Hunter Clark Coker 9134 Pioneer 2684

Cultivar Wheat Screening Trial; Plains 2001.

Sencor Rates Limited by Soil Types u Label: wheat 2 leaf - 2 tiller soil texture coarse medium fine u organic matter 0. 75 0. 094 lb ai 0. 125 lb ai 2. 0 0. 125 lb ai 0. 1875 lb ai UGA research shows we need 0. 25 to 0. 31 lb ai per acre when wheat is 3 to 4 leaf

Sencor Rates Limited by Soil Types u Need ideal weather conditions: warm (not hot) periods with optimum wheat and ryegrass growth no significant rainfall for several days u Do not add crop oil u May add nonionic surfactant but may see ~10% additional injury

Sencor Efficacy on Ryegrass Locations 1* 2* 3* 4** 5* Sencor (0. 25 - 0. 31 lb ai) 80 87 78 53 97 Hoelon (0. 5 - 0. 75 lb ai) 93 94 69 26* *Ryegrass 94 3 leaf or less **Ryegrass 1 tiller or larger *Hoelon resistant ryegrass present.

Alternatives to Hoelon • Currently available: Finesse Hoelon Sencor Axiom • In development: Mesosulfuron

Axiom 68 DF • Section 18 granted for 29 GA counties

Georgia counties infested with diclofop-resistant Italian ryegrass. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. Bleckly Bullock Burke Chattooga Crawford Dooly Early Elbert Franklin Glascock Hart Jefferson Johnson Laurens Lee Macon Peach Pulaski Randolf Schley Screven Sumter Taylor Terrell Twiggs Walker Washington Webster Wilkinson 26 4 9 11 8 10 27 5 17 23 20 19 7 6 22 28 24 18 16 15 25 1 29 12 3 13 14 21 2

Section 18 Granted for Axiom • New wheat herbicide by Bayer • 54. 4% flufenacet + 13. 6% metribuzin • 6 to 10 oz of product on medium or fine textured soils (8 to 10 oz for most soils) • Do not apply preemergence

Axiom at 8 oz PRE Non-treated Experiment at Griffin, GA during 2000/2001 season

Wheat Response to Axiom. Plains, GA, 2001. * Axiom 10 oz PRE *Axiom applied to emerged wheat caused no significant injury. Non-treated

Section 18 Granted for Axiom • New wheat herbicide by Bayer • 54. 4% flufenacet + 13. 6% metribuzin • 6 to 10 oz of product on medium or fine textured soils (8 to 10 oz for most soils) • Do not apply preemergence • Apply to spike wheat hopefully before ryegrass emerges (must be activated by rainfall or irrigation)

Ryegrass Response to Axiom. Averaged over Plains and Tifton, GA 2001/2002. 26 DAP % injury 95 98 73 80

Late-season Italian ryegrass control by Axiom applied at spike wheat. Plains and Tifton GA. 2001 and 2002. % 84 52 Spike ryegrass 2 -leaf ryegrass Experiment designations, left to right: Tifton, 2001; Plains, 2002. Axiom applied at 9 oz/A.

Hoelon is still more effective than Axiom on non-Hoelon resistant ryegrass if a timely application is made

Alternatives to Hoelon • Currently available: Finesse Hoelon Sencor Axiom • In development: Mesosulfuron

Ryegrass Response to Mesosulfuron. North Carolina, 2001. Non-treated Mesosulfuron POST

Late-season Italian ryegrass control by mesosulfuon plus iodosulfuron applied postemergence. Plains and Tifton GA. 2001 and 2002. 93 94 % 99 Experiment designations, left to right: wheat 3 -01; wheat 5 -01; wheat 6 -01; Average. Mesosulfuron applied at 12. 5 g ai/ha mixed with iodosulfuron at 2. 5 g ai/ha. 95

Weed Control Update for Wheat Managing Ryegrass

Broadleaf Weed Control Options Sencor Peak MCPA Express Buctril Harmony Extra Bronate 2, 4 -D Finesse Clarity

Harmony Extra Rate: 0. 3 to 0. 6 oz/A for wheat & barley (0. 5 oz in general); 0. 3 to 0. 4 oz for oats Timing: 2 -leaf until flag leaf visible Adjuvant: 0. 25% NIS in water 0. 125% NIS in nitrogen Weeds: Controls garlic and most broadleaf weeds Mixes: 2, 4 -D to improve cornflower, wild radish, and vetch Rotations: No restrictions of concern Grains: Wheat, barley, oats

Express 1. effective on wild radish, wild mustard, and other broadleaf weeds 2. 2 -lf stage until just before flag leaf wheat and barley 3. less effective than Harmony Extra on garlic, henbit, shepherdsurse, and wild radish. No rotational restrictions of concern 4. tank mix with 0. 125 to 0. 375 lb ai of 2, 4 -D or MCPA

Express Rate/timing: 0. 25 to. 33 oz POST, after 2 lf to flag leaf Adjuvant: 0. 25% NIS Carrier: water or specific N Weeds: Less effective than Harmony Extra on garlic, henbit, and shepherdsurse Mixes: Mix with 0. 25 to 0. 5 pt/A of MCPA or 2, 4 -D Rotations: No rotation restriction Grains: Wheat, barley

MCPA 1. ) Similar to 2, 4 -D, 0. 5 to 1 pt/A POST 2. ) After wheat has 2 tillers (some labels allow application after 2 leaf) but before jointing (oats should be fully tillered) 3. ) Wheat, barley, rye, oats

2, 4 -D 1. Controls most broadleaf weeds except chickweed, henbit, knawel. For wild garlic and wild onion, increase rate according to label. 2. Apply after fully tillered but before jointing in wheat, oats, barley, and rye

Susceptibility of Small Grains to Phenoxy Herbicides Flowering Jointing Heading Seedling Fully tillered Increasing tolerance Soft dough As Affected by Growth Stage

Bushels/A Wheat Response to 2, 4 -D. Macon County, 2000. 73 53 Wheat Stage at Time of Application

Wild garlic • Not a yield problem • Major quality problem

Wild Garlic Control in Wheat Harmony Extra: 0. 5 to 0. 6 oz garlic < 12”, 2 -4” new growth Peak: 0. 25 to 0. 5 oz garlic < 6 -8” rotational concerns 2, 4 -D ester: 2 pt; after tillering, before jointing injurious to wheat

Wild radish size response to grain herbicides. Herbicide 0 -8 inch 8 -14 inch bolting 2, 4 -D 90+ 70 -80% <50% MCPA 90+ 50 -70% <30% MCPA + Express 90+ 80 -85% <65% Peak 90+ 75 -85% <50% Express 90+ 50% <50% Harmony Extra 90+ 50% <50%* *At some stage after bolting becomes more susceptible.

Preharvest Herbicide Options for Small Grains Crop Wheat & Herbicides Rate 2, 4 -D amine* 1 -2 pt Barley, Rye 2, 4 -D ester* Remarks Hard dough stage or later. 1 -2 pt Oats 2, 4 -D acid/ester 1 -2 pt Wheat Glyphosate 0. 5 to After hard dough stage 1. 5 lb ai (30% or less moisture), at least 7 days before harvest. Not for seed wheat. *3. 8 L formulations