Corn Traits: What Pays in Virginia

1. Corn Traits: What Pays in Virginia Wade Thomason

2. Pests • Weeds • Barnyardgrass, bermudagrass, broadleaf signalgrass, crabgrass, fall panicum, foxtails, goosegrass, johnsongrass, quackgrass, sandbur, shattercane, texas panicum, nutsedge, Eastern black nightshade, burcucumber, cocklebur, jimsonweed, lambsquarters, morningglory, pigweed, ragweed, sicklepod, smartweed, spurred anoda, prickly sida, tropic croton, velvetleaf

3. Pests • Weed Control Programs • Tillage? • Cover Crop? • Pre vs. Post? • Crop Rotation? • Weeds Present? • Selective herbicides vs. non-selective? • Simplicity? • Cost?

4. Herbicide Tolerance • Glyphosate tolerance • Glufosinate tolerance • Imidazolinone tolerance

5. Herbicide Tolerance Imidazolinone tolerant - IMI (IR or IT) or Clearfield (Cl) • Developed by tolerance selection to be resistant/tolerant to imidazolinone herbicides (pursuit, scepter). • Originally introduced to deal with herbicide carryover. • Products like Lightning can be directly applied - controls a broad spectrum of weeds and volunteer RR corn • Some IMI varieties (IR) also are tolerant to some sulfonylurea (e.g., Accent, Exceed) and sulfonamide (Broadstrike products, Python) herbicides and are used to reduce the injury potential of these products when applied alone or in combination with organophosphate (OP) insecticides.

6. Herbicide Tolerance Glyphosate Tolerance/Roundup Ready - RR • Developed using genetic engineering techniques. • Allows postemergence applications of Roundup and some other glyphosate products directly to corn. • This system provides broad-spectrum annual and perennial weed control in corn.

7. Herbicide Tolerance LibertyLink Glufosinate resistant (Gu) corn • Genetically engineered to allow over-the-top applications of Ignite (glufosinate) herbicide. • This program should provide broad-spectrum control of annual broadleafs and grasses of low to moderate pressure. • Sequential applications or tank mixtures may be required for new weed flushes and perennials.

8. Approximately 1200 growers in six states (approximately 200 per state in Iowa, Illinois, Indiana, Mississippi, North Carolina, and Nebraska)

9. 103.0 102.0 101.0 RELATIVE YIELD, % 100.0 99.0 98.0 97.0 GY TOLERANCE GU TOLERANCE IMI TOLERANCE NONE Herbicide Tolerance Traits

10. 2009 State Grain, Shenandoah 3 bu/ac advantage?

11. Avg 2007-2009 Isolines Study, Blacksburg 1.1 ton/ac advantage?

12. Cost:Benefit $4/bu

13. Where to put these products and how to manage them: • Herbicide tolerance • Target hard-to-control weeds. • Evaluate “real” costs • Consider weed management in other crops • Resistance management

15. Chronic Pest Problems

16. European Corn Borer

17. European Corn Borer • An average of one European corn borer cavity per stalk across an entire field can reduce yield by as much as 5% by the first generation and 2.5% by the second generation. • BUT…prediction insect populations prior to the season is not reliable. • BUT…treating for the pest in-season is difficult at best.

18. European Corn Borer • Thresholds: • First Generation ECB • 80 percent or more of the plants exhibit whorl feeding damage and if 80 percent or more of the damaged plants (i.e., 8 out of the 10 dissected plants) have at least 1 live larva per plant. (V4 or 10-12 inch plants) • Second Generation ECB • 35 percent or more of the plants in the pre- to post-tasseling stage of development have at least 1 egg mass per plant. (24 inch plants – tassel)

19. European Corn Borer • Statewide economic infestations have occurred in only 3 out of the last 22 years. • Many corn hybrids are able to tolerate moderate levels of leaf and stalk injury without economic yield loss. • Also, corn grown for silage rarely needs to be treated for ECB.

20. European Corn Borer • How often is any particular field likely to have an average of one or more cavities per stalk at the end of the season?

21. ECB • What is the benefit? • Of 172 cornfields surveyed from 1997-99, only 2% exceeded the economic threshold for ECB damage (1 or more, > 0.5-inch tunnels per stalk) (Youngman). • 2004 Eastern VA on-farm plots • 17 trials reported • 6 had obvious ECB damage • 10% infested  +14 bu/A • 25% infested  +30 bu/A • 90% infested  +54 bu/A

22. CB Bt Effects 2005 Corn borer tunnels/plant:2.0 2.1 4.0 2.7 Average of three hybrids *Significantly different Average benefit: 2.7 Tons/A 4.2% /tunnel yield response

23. CB Bt Effects 2006 Corn borer tunnels/plant:1.1 0.8 0.8 0.9 Average of three hybrids *Significantly different Average benefit: 1.4 Tons/A 6.2% /tunnel yield response

24. ECB • Most corn (≥ 90%) planted timely in Virginia will likely not realize an economic benefit from Bt corn because of the lack of European corn borer pressure early in the season. • But gain protection from corn ear worm, fall armyworm, black cut worm (Cry1f only), and indian meal moth in shelled corn. • It is strongly recommended that Bt corn be planted anywhere late-planted corn (i.e., corn planted mid to late May or later) is grown in Virginia because of the increasing risk of corn borer damage.

25. ECB

26. Where to put these products and how to manage them: • European Corn Borer • A history of significant ECB damage in a field • Very early-planted long-season hybrids will be attractive to both first- and second-generation ECB. • Very late plantings will also be attractive to ECB • Fields planted in low areas along streams and rivers are more like to experience economic infestations of ECB. • Fields managed for high yield or at higher population levels will benefit more from the technology than those with a low yield potential (for example, 3% of 150- bushel-per-acre corn is greater than the same percentage of 100- bushel-per-acre corn).

27. Corn Root Worm

28. Corn on Corn: No-till

29. Corn on Corn after Rye

30. Late Planted Corn on Corn

31. Corn on Corn and Drought In Summary… • Opportunities exist in our region for transgenic hybrids for silage production • Later planted (CB) • Corn on Corn (RW) • Weed issues • Stress

32. 2005 RW Bt Silage Effects Corn Rootworm (0-3) rating:0.16 0.12 0.97 0.42 RW/Force advantage: 1.4 Tons/A CB + RW effect: 3.1 tons/A Average of three hybrids *Significantly different from RW Bt

33. 2006 RW Bt Silage Effects Corn Rootworm (0-3) rating:0.28 0.09 1.03 0.47 RW/Force advantage: 0 Tons/A CB+RW effect: 1.7 Tons/A Average of three hybrids *Significantly different from RW Bt

34. RW Bt Silage Effects 2006 Average of three hybrids Forage quality effects NS

35. Effects of Traits on Mycotoxins 2006

36. Preliminary Conclusions: • CB BT had significant effect on yield in medium high pressure environments • Average yield response 5.2%/tunnel or 2.0 tons/A • No effect on forage quality • RW BT had significantly higher yields than Force in one of two years • Average difference between RW and Force was 0.7 tons/A • No effect on forage quality • CB RW BT had significant effect on yield in at least one of two years • Average yield response compared to check was 2.4 tons/A • No consistent effect on mycotoxins

37. Corn Root Worm • Economics

38. Corn Root Worm • Economics

39. Where to put these products and how to manage them: • Corn Root Worm • A history of significant CRW damage in a field usually is a good indicator that the conditions in the field are conducive to the pest. • Flourish with continuous corn or with pumpkins in the rotation. • Scouting is highly predictive.

40. Corn Root Worm • Western corn rootworm beetles should be sampled in July and August to determine whether a control measure is needed the following year. • Sticky traps • Scouting for adults • When scouting fields that have been in corn more than one year, an average count of 1.0 beetle or more per ear zone indicates that a granular insecticide should be applied if the field is to be planted in corn the following year. When scouting first year corn, control for rootworms the following year if the average count is 0.75 beetles or more per ear zone, because primarily egg-laying females migrate to new cornfields.

41. Corn Traits: What Pays in Virginia • It depends: • CB protection alone adds 0.4 to 2.0 ton/ac silage (ave = 0.8 ton/ac) • CB+CRW (when CRW is present) adds 2.0 to 3.0 tons/ac • Will the added yield pay for the added cost?