Understanding Emergence & Stand Problems in No-Till Corn

1. Understanding Emergence & Stand Problems in No-Till Corn R.L. (Bob) NielsenAgronomy Dept.,Purdue UniversityWest Lafayette, IN 47907-1150ph. (765) 494-4802Internet:rnielsen@purdue.edu

2. A Common No-Till Lament…. • “Getting a good stand of no-till soybeans is easy, but... • Getting a good stand of no-till corn can be a pain in the rear!” RLNielsen, Purdue Univ.

3. Why Worry About Variable Stand Establishment? Only because uniform and vigorous stands of corn are required for attaining optimum yields. RLNielsen, Purdue Univ.

4. Yield Loss From Variable Stands... • Regardless of tillage, uneven stand establishment in corn reduces yield potential from Day 1. • Yield losses due to uneven stand establishment can easily approach 7 to 15 bu./ac. • This yield loss cannot be recovered. RLNielsen, Purdue Univ.

5. What isStand Establishment Variability? • Plant Spacing Variability • How evenly are the seedlings spaced? • Plant Emergence Variability • Do all the seedlings emerge the same day? • Plant Growth Variability • Do all the seedlings continue to grow vigorously and uniformly? RLNielsen, Purdue Univ.

6. Successful Germination & Emergence Require... • Adequate Soil Temperatures • Consistently greater than 50o F RLNielsen, Purdue Univ.

7. Typical Soil Temperatures RLNielsen, Purdue Univ.

8. Soil Temperature & Corn Emergence RLNielsen, Purdue Univ.

9. Successful Germination & Emergence Require... • Adequate Soil Temperatures • Adequate Soil Moisture • Too wet = Dead kernel • Just right = Germination • Too dry = Inert kernel RLNielsen, Purdue Univ.

10. Successful Germination & Emergence Require... • Adequate Soil Temperatures • Adequate Soil Moisture • Adequate Seed-to-Soil Contact • Seed-to-residue contact is not good! • Seed-to-rock contact is not good! • Seed-to-clod contact is not good! RLNielsen, Purdue Univ.

11. Successful Germination & Emergence Require... • Adequate Soil Temperatures • Adequate Soil Moisture • Adequate Seed-to-Soil Contact • Pest-Free Conditions • Grubs, wireworms, seedcorn maggots • Seed rots, seedling blights RLNielsen, Purdue Univ.

12. Germination & Emergence Success Do Not Guarantee Successful Stand Establishment! What other secretsdo you know? RLNielsen, Purdue Univ.

13. Healthy kernel, seed roots, and mesocotyl Until permanent roots are established, a seedling depends primarily on the energy reserves of the kernel. These energy reserves are translocated through the connecting mesocotyl ‘pipeline’. Successful Seedling Establishment Depends On Two Criteria... RLNielsen, Purdue Univ.

14. Corn Mesocotyl • Tubular, white, stemlike tissue that connects kernel and base of coleoptile. • Mesocotyl cell elongation elevates coleoptile to soil surface. RLNielsen, Purdue Univ.

15. Successful Seedling Establishment Depends On Two Criteria... • Healthy kernel, seed roots, and mesocotyl • Successful establishment of the permanent (nodal) root system • Adequate soil moisture • Adequate soil temperatures • Adequate soil tilth • Pest-free conditions RLNielsen, Purdue Univ.

16. Seminal roots originate from the first node located within the seed embryo. Radicle root and lateral seminal roots. Serve mainly to anchor seedling. Minimal uptake of water & nutrients. Cease new growth shortly after seedling emergence. Practically-speaking, Corn Has Two Root Systems... RLNielsen, Purdue Univ.

17. Practically-speaking, Corn Has Two Root Systems... • Seminal roots originate from seed embryo • Nodal roots originate from stalk nodes • Elongate shortly after seedling emergence. • First set visible by 1-leaf collar stage • One set of roots for every below-ground node plus 1 or more above ground. • By 6-leaf collar stage, are main roots of plant. RLNielsen, Purdue Univ.

18. Growth Stage VE (Emergence) Seminal roots Swelling of 1st nodal roots RLNielsen, Purdue Univ.

19. Growth Stage V2 (two leaf collars) 2 1 1st set of nodal roots Seminal roots RLNielsen, Purdue Univ.

20. 5 3 1 Growth Stage V5 (five leaf collars) Nodal roots RLNielsen, Purdue Univ.

21. In summary,Critical Period for Seedling Establishment Is From Emergence to Knee-High • Damage to the kernel or mesocotyl prior to establishment of nodal root system will stunt or kill the seedling • From about growth stage VE to about V3 • Damage or stress to the 1st few sets of nodal roots can severely stunt corn plant. • From about growth stage V3 to about V6 RLNielsen, Purdue Univ.

22. Root Trivia Question... Do roots grow TOWARD water and nutrients? “Water at 1 foot, sir!” “DIVE! DIVE!” RLNielsen, Purdue Univ.

23. Root Trivia Answer... No! Root growth occurs where conditions are favorable, not in anticipation of favorable conditions. RLNielsen, Purdue Univ.

24. A related root question…. If roots develop where conditions are favorable, what are the primary factors that determine whether roots develop shallow or deep in the soil? RLNielsen, Purdue Univ.

25. Root Location Depends On... • In some fields, root depth is dependent on the presence of soil compaction or hard pans. RLNielsen, Purdue Univ.

26. More importantly, Root Location Depends On... • Soil temperature & moisture in May & June • Warm, dry soils encourage deep rooting. • Cool, wet soils encourage shallow rooting. Among other things, root location affects crop’s 1) nutrient uptake patterns and 2) drought tolerance. RLNielsen, Purdue Univ.

27. What’s Different About No-Till? RLNielsen, Purdue Univ.

28. Trash, trash, and more trash! • TRASH: Stover, stubble, and other plant materials left from previous crops or weeds that directly or indirectly interferes with corn germination, emergence, & seedling growth. • RESIDUE: Stover, stubble and other plant materials left from previous crops or weeds that conserve soil moisture and improve soil tilth. RLNielsen, Purdue Univ.

29. Bad Effects of Trash... • Delays soil drying and warmup • Delays or causes uneven germination • Hinders early root & shoot growth RLNielsen, Purdue Univ.

30. If Seedling Growth is Slow... • Increases exposure time to damaging soil-borne pathogens, insects or pesticides. • Delays roots’ encounters with soil nutrients. • Decreases the effective length of the growing season. • No-till corn is often literally younger than conventional till corn planted same day! RLNielsen, Purdue Univ.

31. Tillage Effects on Soil Temperature • No-till averaged 3-4 fewer soil-based GDD per day than plow. • Over 5 weeks of growth, translates to about 2 leaf stage delay in development for no-till. Average temperatures during 1st five weeks after planting. 1991-93, westcentral INContinuous corn, SiCL RLNielsen, Purdue Univ.

32. Bad Effects of Trash... • Delays soil drying and warmup • Can hinder planter operation, especially when accompanied by wet soils. RLNielsen, Purdue Univ.

33. Surface Trash and/or Wet Soil = Nightmare For Planters! • Hairpinning of residue into slot • Wet residues are difficult to cut • Wet, soft soil = sponge-like cutting board • Dull coulters do not help! Kernel Pinned residue RLNielsen, Purdue Univ.

34. Surface Trash and/or Wet Soil = Nightmare For Planters! • Hairpinning of residue into slot • Uneven seed depth • Caused by uneven residue distribution and/or excessive planting speeds RLNielsen, Purdue Univ.

35. Surface Trash and/or Wet Soil = Nightmare For Planters! • Hairpinning of residue into slot • Uneven seed depth • Decreased closing wheel effectiveness • Insufficient down pressure = Open planter slots • Excessive down pressure = Compacted furrow RLNielsen, Purdue Univ.

36. A problem related to slot closure... Example: 1993 growing seasonSandy loam soilPrevious crop = SoybeanPlanted “on the wet side”Trouble closing the slots25+% emerging underground Farmer: “Must be fertilizer dealer’s fault!” RLNielsen, Purdue Univ.

37. Normal Emergers • Growth stage ~ V2 • Seeding depth ~ 1” • Reasonable rooting RLNielsen, Purdue Univ.

38. Delayed Emergers • Leafed out underground • Trying to pull itself out • Fairly dense soil surface RLNielsen, Purdue Univ.

39. Another Example • Delayed emergence • Leaves emerged just below soil surface, but successfully Coleoptile RLNielsen, Purdue Univ.

40. Brush the soil away and you see... • Flattened coleoptile • Flattened mesocotyl • Smooth compacted sidewalls “Smooth as a baby’s ….” RLNielsen, Purdue Univ.

41. Side View of Delayed Emerger • Flattened coleoptile • Flattened mesocotyl • Smooth compacted sidewalls RLNielsen, Purdue Univ.

42. Top View of Delayed Emerger • Seminal root growth confined to furrow RLNielsen, Purdue Univ.

43. Surface Trash and/or Wet Soil = Nightmare For Planters! • Hairpinning of residue into slot • Uneven seed depth • Decreased closing wheel effectiveness • Sidewall compaction in furrow • Caused by double-disc openers smearing sides of furrow • Can cause delayed emergence or leafing out underground RLNielsen, Purdue Univ.

44. Bad Effects of Trash... • Delays soil drying and warmup • Can hinder planter operation • Surface trash harbors disease inoculum that can cause... • Seedling blights • Leaf diseases • Root and stalk rots RLNielsen, Purdue Univ.

45. Bad Effects of Trash... • Delays soil drying and warmup • Can hinder planter operation • Surface trash harbors disease inoculum • Surface trash favors pesky critters • Slugs • Seedcorn maggot • Brown stinkbug • Stalk borer RLNielsen, Purdue Univ.

46. You be the detective…. • Originally no-till planted May 20 • Northeast Indiana • Corn emerged fine • Began to “suffer” at “two to three” leaf stage, resulting in significantstand loss • Replanted June 26 Farmer: “Must be chemical dealer’s fault!” RLNielsen, Purdue Univ.

47. Appearance of Survivors • Stunted growth • Deformed growth • Prominent tillering • Unusual leaf stripes RLNielsen, Purdue Univ.

48. Deformed Inner Stalk Appearance • Split stalks revealed “gnarly” “innards” RLNielsen, Purdue Univ.

49. What’s Your Diagnosis? • The stunting, deformed growth, necrotic leaf stripes, tillering and “gnarly innards” are all symptomatic of physical injury near to the growing point at an early stage of development. • Hail or frost damage • Stinkbug injury • Stalk borer injury RLNielsen, Purdue Univ.

50. So What’s A Guy To Do? • Planting date RLNielsen, Purdue Univ.