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Pecan Fertility and Orchard Floor Management

Pecan Fertility and Orchard Floor Management. Lenny Wells UGA Extension Horticulture---Pecans. Leaf Sampling. Sample trees between July 7th and August 7th.  Use terminal shoots exposed to the sun.  Collect leaflets from all sides of the tree. 

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Pecan Fertility and Orchard Floor Management

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  1. Pecan Fertility and Orchard Floor Management Lenny Wells UGA Extension Horticulture---Pecans

  2. Leaf Sampling • Sample trees between July 7th and August 7th.  • Use terminal shoots exposed to the sun.  • Collect leaflets from all sides of the tree.  • Avoid leaflets damaged by insects and diseases.

  3. Leaf Sampling • Abnormal trees or trees not representative of the area should be sampled and sent separately.  • Sample trees of the predominant variety in a given block. • Immediately upon collection, wipe leaves (entire surface, boh top and bottom) with a damp cellulose sponge or cheese cloth to remove dust and spray residue.  • Do not allow   the leaves to come into contact with rubber or galvanized containers.  • If recent soil test data is not available, it would be advisable to collect a soil sample and have it sent to the Soil Testing Laboratory.

  4. Soil Sampling • Useful for pH and toxicities • Late Fall/Winter • Sample uniform area • 1 pint/sample (15-20 cores) over large area • Sample to 8” depth

  5. Nitrogen • N absorption by roots is driven by demand • Demand is regulated by growth of leaves or fruit, and production of proteins. • Flowers may be aborted if leaf N is deficient the previous summer

  6. Nitrogen Leaf Concentration: 2.5-3.3% (Apply when less than 3) 10 lbs N/100 lbs expected crop Shoot growth should be 8-12”

  7. Nitrogen • In well managed, irrigated orchard soils, N can move more readily and leach out of the effective root zone before it is taken up by the tree. • Initial spring N used by developing foliage comes from storage pools within the tree. • N demand will be greatest for “on” trees bearing a heavy crop load, since expanding leaves, shoots, and fruit create the greatest demand.

  8. Nitrogen • General Recommendation: • 75-100 lbs N applied mid-late April • Examine Crop in June/July • “On Year”---50 lbs around August 15 • “Off Year”---0 lbs around August 15 OR IF NO AUGUST APPLICATION • 75 lbs N in March/April (March after “on year”) • 25-75 lbs in late May/Early August • Most of the N taken up during the kernel-fill stage will supply the N storage pool needed for early spring growth. • Timing of fertilizer application for non-irrigated or run-down orchards will be different

  9. Nitrogen Dry-Land /Neglected Orchards • 75 lbs N in March • 25 lbs in late May Young trees • Year 1: 1 cup ammonium nitrate in June if growth is good (2-4’ terminal growth) • Year 2: 1 cup in April, 1 in May, and 1 in June • Year 3-4: 2 cups in April, May, and June • Year 5-7: 4 cups in April, May, and June + • Year 1:1 lb 10-10-10 fertilizer distributed in a 25 sq. ft. area around the tree(apply in June if growth is good) • After Year 1:4 lbs of 10-10-10 fertilizer for each inch of trunk diameter (measured one foot above soil surface). Do not place fertilizer within 12 inches of the trunk • 1 lb zinc sulfate per tree for the first three years following planting.

  10. Nitrogen • Fertilizing on a per tree basis • Mature trees • 1 lb amm. Nitrate/inch of trunk diameter in late March before bud break. Water in promptly • If lawn is concern, bore holes in ground and pour in, then water area + • 4 pounds of 10-10-10 for each inch of trunk diameter (measure 4 1/2 feet above soil level) up to 25 lbs/tree. This fertilizer should be applied in late March before bud break. Zinc needs are best determined by analysis of leaf samples taken in late July or early August. (Max 2 lbs/tree)

  11. Clover as a Source of Nitrogen • Crimson – 100 lbs N/A • 10 lbs/A seeding rate • 1.00-1.50/lb • White Clover--103 lbs N/A • 4 lbs/A seeding rate • 2.00-2.50/lb • Use mixture • Allow clover to re-seed • Apply Poast in February

  12. Potassium (K) • K is transported to nuts at leaf’s expense • 50-100 lbs K applied in February/March • During “on” year apply additional 30 lbs K in mid August • 1.25-2.5 ppm in leaf analysis • Manage N/K ratio to 2:1 • Manage Mg---(No Dolomitic lime above .45% Mg) • Deficiency most common on Desirable and Schley

  13. Basal Leaf Scorch • Usually occurs in June/July • Results from imbalance between N/K • More susceptible to winter injury • Defoliation • Occurs on basal leaves of shoot and moves upward • Scorched areas circular or oblong/ dime size

  14. Basal Leaf Scorch • Maintain adequate K levels • When K level is marginal or deficient, N level should be reduced until K is corrected • Foliar K can help, but does not replace soil applied (Potassium Nitrate: 3 lbs/100 gallons)

  15. Zinc • Necessary for shoot elongation, leaf expansion, and yield • Apply when Zn in leaf is below 50 ppm • 2 lbs Zinc sulphate + 3 lbs Potassium Nitrate/100 gallons • Begin 2 wks after budbreak until shoot elongation complete

  16. Mouse Ear • Nickel Deficiency • Zinc Management • Nickel lignosulfonate • Apply 1 pt/A in spring (April) while canopy is developing (parachute stage); • 2nd application: 1 pt/A 30-60 days after 1st appl. • Third application of 1.5-2 pts/A in late Sept.-early October before leaf fall to prevent mouse ear in the spring flush.

  17. Magnesium • 0.35-0.6% leaf • Deficiency occurs on acid soils (pH <5.5) • High K or Ca • Use Dolomitic lime • Maintain pH of 6.0-6.5 • OK to use calcitic lime when Mg above 0.45% • If pH adequate, apply foliar Magnesium Sulfate at 5 lbs/100 gallons (4” shoot growth to July)

  18. Chicken Litter • Have sample analyzed • Typically 70 lbs N/ton; 35 lbs P; 40 lbs K; 0.6 Zn • Nutrients are organically bound • Organic matter adds tilth/water-holding capacity to soil • Apply between late February and early June • Use BROILER litter and NOT LAYER litter • Ca/Mg

  19. Water Split • Occurs in August/September on Certain Varieties (late water stage/early shell hardening) • Split occurs along ½ length of fruit and may penetrate shuck and shell • Rapid influx of water • Rain/Irrigation/ High humidity/Low solar radiation

  20. Water Split • Occurs w/in 24 hrs of heavy influx of water to soil • Most split occurs in upper 1/3 of canopy • Split occurs in pre-dawn hours • Fruit falls from tree within 7 days of splitting

  21. Managing Water Split • Maintain soil moisture 2-3 wks before shell hardening (limited) • Fruit thinning • Avoid excessive N • Micronutrients? • B, Ni, Cu

  22. Orchard Floor Management • Mature Trees • Early Spring Pre-Emergence: • Simazine—2-4 qts/A Control of Annual Broadleaf weeds and some ann grasses Use low rate on sandy soil OR • Surflan 2-4 qts/A + Simazine—2-4 qts/A Broader Spectrum • Karmex 2-4 LBS Do Not use on sandy soil; Do not graze • Spring Post: (Can be mixed with pre-emerge applications) • Gramoxone Max 1.75-2.7 pts or Boa 2-3 pts 20 GPA Volume improves control Add 1 gal crop oil /100 gal spray mix Broad Spectrum of Annual weeds when small and succulent Do NOT contact foliage, green bark or allow animals to graze OR • Poast 16 oz/A-----Clover release

  23. Orchard Floor Management • Summer Burndown Herbicides: (Do NOT contact foliage or green bark) • Roundup (Glyphosate) 1-2 qts/A OR • Roundup+Karmex 2-4 lbs Use low rate on sandy soil OR • Gramoxone Max 1.75-2.7 pts • Rely 3-6 qts/A Better on perennials

  24. Orchard Floor Management • Eliminate grass and weed competition under orchard trees • Non-Bearing Trees • Pre-Emergence (after soil settles) • Surflan 2-4 qts/A • Surflan+Simazine (At least 2 yrs old) • Prowl 2.4-4.8 qts (after soil settles) • Solicam 2.5-5lbs. (after soil settles) • Post-Emergence • Roundup (Glyphosate) 1-2 qts/A • Rely (Glufosinate) 3 -6 qts/A • Poast 16 oz/A OR Fusilade 16 oz/A 1 qt crop oil low spray volume (10 GPA) increases activity (no broadleaf activity) Do NOT contact foliage or green bark

  25. Basic Needs of the Pecan Crop • Light • Water • Leaf Retention • Management of Crop Load • Pollination

  26. Pecan Irrigation • 71,031 Irrigated Pecan Acres in GA (~50% of crop) based on UGA Farm Gate & Irrigation Surveys • Average Amount Applied/Year = 15.5” • Average Cost/Year = $64.50/A • 18,254 Acres irrigated by solid-set • 52,777 Acres irrigated by drip

  27. Irrigation Schedule for Pecans MONTH SPRINKLER DRIP Inches/A % cycle April 0.5” 60 May 0.75” 70 June 1” 80 July 1.25” 90 August 1.5” 100 September 1.5” 100 October 1” 90 November 0.5” 60

  28. Pollination • Desirable (I) – April 23-May 4 • Cape Fear (I) – April 22-May 4 • Stuart (II) -- April 22-April 29 • Sumner (II) -- April 22-April 28 • Elliott (II) – April 19-April 30 • Schley (II) – April 19-April 27 Pistil Receptivity Pollen Shed • Desirable (I) – April 23-April 28 • Cape Fear (I) – April 23- April 30 • Stuart (II) – April 28-May 7 • Sumner (II) – May 1-May 7 • Elliott (II) – April 27-May 3 • Schley (II) – April 23-May 3

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