1. Weed Control Update for Wheat 2003 A. Stanley Culpepper and Alan C. York

2. Italian Ryegrass Control with Hoelon

3. Hoelon is still excellent material where resistance is not a problem

4. Hoelon Rate for POST on Wheat Ryegrasspt/acre 1- to 3 leaf 1.33 3- to 4-leaf 1.33 to 2 5-leaf, 2 tillers 2 to 2.67

5. Proper Timing of Hoelon POST Timeliness is critical !!! With normal planting date, generally best to apply before Christmas 1.5 pt before Christmas is better than 2.67 pt in February/March

6. Use of Adjuvants with Hoelon POST on Wheat Can add COC May enhance control, especially large ryegrass Increases risk of crop injury, especially under cool, wet conditions COC generally not recommended

7. Hoelon POST on Wheat and Weather Avoid cold, wet conditions Do not apply if temperature for preceding three days drops below 35 degrees

8. Hoelon POST on Wheat Carriers and Tank Mixes Apply in water only; do not use nitrogen as carrier; reduced control Do not tank mix with other herbicides; reduced control May tank mix with Tilt and other fungicides; timing for Hoelon and fungicides do not coincide

9. Alternatives to Hoelon for Ryegrass Control

10. Alternatives to Control Hoelon-Resistant Ryegrass 1. Finesse 2. Axiom* 3. Clearfield system** 4. Mesosulfuron*** *Available under Section 18 for 2003/2004 **Varieties not available ***Not registered yet

11. Alternatives to Control Hoelon-Resistant Ryegrass 1. Finesse

12. Finesse 75 DF Premix of two SU’s 62.5% chlorsulfuron, 12.5% metsulfuron Good broadleaf control Suppression of ryegrass (variable results; dependent upon timely rain for activation) Applied PRE or POST; PRE usually best on ryegrass

13. Mid-Atlantic University Trials 1999 and 2000 % control, late Data summarized by DuPont; data from South Carolina through Delaware Finesse 0.5 oz PRE 16 loc 51% Finesse 0.4 oz POST 19 loc 40%

14. Late-season Italian ryegrass control by Finesse at 0.5 oz/acre applied preemergence. North Carolina data. Individual locations Avg of 10 locations % 56 45 93 35 94 76 88 58 28 18 27

15. Late-season Italian ryegrass control by Finesse at 0.4 oz/acre applied early postemergence. North Carolina data. % 37 56 60 35 56 65 10 4 13 Individual locations Avg of 8 locations

16. Finesse 75 DF Premix of two SU’s 62.5% chlorsulfuron, 12.5% metsulfuron Good broadleaf control Suppression of ryegrass (variable results) Rotational concerns

17. Rotational Restrictions for Finesse Crop Interval STS soybeans 6 months Non-STS soybeans18 months Cotton, corn18 months NC experience: no problem with STS beans; variable results with non-STS beans

18. Finesse carryover on non-STS beans T. Pegram, NCSU

19. Alternatives to Control Hoelon-Resistant Ryegrass 1. Finesse 2. Axiom

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

21. Axiom herbicide Mixture of two herbicides (4:1) 54.4% flufenacet + 13.6% metribuzin GA obtained Sect 18 exemption in fall 2002; applied for Sect 18 in fall 2003 Timing of application: wheat: emergence to 2- to 3-leaf stage ryegrass: before 1-leaf stage

22. Axiom Why application to spike-stage wheat? Why not apply PRE (behind drill)?

23. Axiom Why application to spike-stage wheat? Why not apply PRE (behind drill)? occasionally injury with PRE on sandy soils if heavy rain before wheat emergence

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

25. Axiom herbicide Rate (oz/A) Soil textureLabel Suggested Coarse4-66 on loamy sand 7 on sandy loam Med/fine6-108 on most fields 10 heavy infestations

26. Axiom herbicide MUST BE ACTIVATED AND TIMELY

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

28. Hoelon-susceptible Italian ryegrass control by Axiom and Hoelon. Average of three locations. A. S. Culpepper, Univ. of Georgia.

29. Hoelon-susceptible Italian ryegrass control by Axiom and Hoelon in Virginia. Avg. of three locations. H. P. Wilson, VPI&SU.

30. Hoelon-resistant Italian ryegrass by Axiom in NC. Avg 2 locations, 2000-01. 10 99 * Axiom 8 oz Johnston Co., 10 oz Union Co.

31. Hoelon-resistant Italian ryegrass control by Axiom and Hoelon in South Carolina. Avg. 3 locations. E. C. Murdock, Clemson Univ. 5 97

32. Alternatives to Control Hoelon-Resistant Ryegrass 1. Finesse 2. Axiom 3. Clearfield system* 4. Osprey* * Future options

33. Osprey GA petitioned for Section 18 emergency exemption in fall of 2002 and again Aug., 2003 EPA “has not had time to review the package and set a tolerance.”

34. Mesosulfuron Untreated

35. Late-season ryegrass control by Osprey applied timely in NC field studies. % Individual loactions (35 total) Average = 95%

36. Broadleaf Weed Control Options SencorPeak MCPA Express BuctrilHarmony Extra Bronate2,4-D FinesseClarity

37. 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

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

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

40. 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:wild radish, wild mustard, Mixes: Mix with 0.25 to 0.5 pt/A of MCPA or 2,4-D Rotations:No rotation restriction Grains:Wheat, barley

41. Express + MCPA 1) Wider window of application: After wheat has 2 tillers (some labels allow application after 2 leaf) but before jointing 2) Better control of henbit and chickweed compared to 2,4-D 3) Cost more than 2,4-D

42. 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