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

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

Leaf Sampling Abnormal trees or trees not representative of the area should be sampled and sent separately. 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. 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. 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. 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. 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.

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

Nitrogen N absorption by roots is driven by demand 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 Flowers may be aborted if leaf N is deficient the previous summer

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

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.

Nitrogen General Recommendation: General Recommendation: lbs N applied mid-late April lbs N applied mid-late April Examine Crop in June/July Examine Crop in June/July “On Year”---50 lbs around August 15 “On Year”---50 lbs around August 15 “Off Year”---0 lbs around August 15 “Off Year”---0 lbs around August 15OR IF NO AUGUST APPLICATION 75 lbs N in March/April (March after “on year”) 75 lbs N in March/April (March after “on year”) lbs in late May/Early August 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

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

Nitrogen Fertilizing on a per tree basis Fertilizing on a per tree basis Mature trees Mature trees 1 lb amm. Nitrate/inch of trunk diameter in late March before bud break. Water in promptly 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 If lawn is concern, bore holes in ground and pour in, then water area+ 4 pounds of 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) 4 pounds of 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)

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

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

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

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

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

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

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

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

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

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

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

Orchard Floor Management Mature Trees Mature Trees Early Spring Pre-Emergence: Early Spring Pre-Emergence: Simazine—2-4 qts/A 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 Surflan 2-4 qts/A + Simazine—2-4 qts/A Broader Spectrum Karmex 2-4 LBS Karmex 2-4 LBS Do Not use on sandy soil; Do not graze Spring Post: (Can be mixed with pre-emerge applications) Spring Post: (Can be mixed with pre-emerge applications) Gramoxone Max pts or Boa 2-3 pts Gramoxone Max 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 Poast 16 oz/A-----Clover release

Orchard Floor Management Summer Burndown Herbicides: Summer Burndown Herbicides: (Do NOT contact foliage or green bark) Roundup (Glyphosate)1-2 qts/A Roundup (Glyphosate)1-2 qts/AOR Roundup+Karmex 2-4 lbs Roundup+Karmex 2-4 lbs Use low rate on sandy soil OR Gramoxone Max pts Gramoxone Max pts Rely3-6 qts/A Rely3-6 qts/A Better on perennials

Orchard Floor Management Eliminate grass and weed competition under orchard trees Eliminate grass and weed competition under orchard trees Non-Bearing Trees Non-Bearing Trees Pre-Emergence(after soil settles) Pre-Emergence(after soil settles) Surflan 2-4 qts/A Surflan 2-4 qts/A Surflan+Simazine (At least 2 yrs old) Surflan+Simazine (At least 2 yrs old) Prowl qts (after soil settles) Prowl qts (after soil settles) Solicam 2.5-5lbs. (after soil settles) Solicam 2.5-5lbs. (after soil settles) Post-Emergence Post-Emergence Roundup (Glyphosate)1-2 qts/A Roundup (Glyphosate)1-2 qts/A Rely (Glufosinate)3 -6 qts/A Rely (Glufosinate)3 -6 qts/A Poast 16 oz/A Poast 16 oz/AOR Fusilade 16 oz/A 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

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

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

Irrigation Schedule for Pecans MONTH SPRINKLER DRIP Inches/A % cycle Inches/A % cycle April 0.5” 60 May 0.75” 70 June 1” 80 July1.25”90 August 1.5”100 September 1.5” 100 October 1” 90 November0.5”60

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