Pecan Fertility and Pecan Fertility and Orchard Floor Orchard Floor ManagementManagement

Lenny WellsLenny Wells

UGA Extension UGA Extension Horticulture---PecansHorticulture---Pecans

Leaf SamplingLeaf Sampling

Sample trees Sample trees between July 7th between July 7th and August 7th. and August 7th. 

Use terminal shoots Use terminal shoots exposed to the sun.  exposed to the sun. 

Collect leaflets from Collect leaflets from all sides of the tree.  all sides of the tree. 

Avoid leaflets Avoid leaflets damaged by insects damaged by insects and diseases. and diseases.

Leaf SamplingLeaf Sampling Abnormal trees or trees not representative of Abnormal trees or trees not representative of

the area should be sampled and sent separately.  the area should be sampled and sent separately.  Sample trees of the predominant variety in a Sample trees of the predominant variety in a

given block. given block. Immediately upon collection, wipe leaves (entire Immediately upon collection, wipe leaves (entire

surface, boh top and bottom) with a damp surface, boh top and bottom) with a damp cellulose sponge or cheese cloth to remove dust cellulose sponge or cheese cloth to remove dust and spray residue.  and spray residue. 

Do not allow   the leaves to come into contact Do not allow   the leaves to come into contact with rubber or galvanized containers.  with rubber or galvanized containers. 

If recent soil test data is not available, it would If recent soil test data is not available, it would be advisable to collect a soil sample and have it be advisable to collect a soil sample and have it sent to the Soil Testing Laboratory. sent to the Soil Testing Laboratory.

Soil SamplingSoil Sampling

Useful for pH and toxicitiesUseful for pH and toxicities Late Fall/WinterLate Fall/Winter Sample uniform areaSample uniform area 1 pint/sample (15-20 cores) over 1 pint/sample (15-20 cores) over

large arealarge area Sample to 8” depthSample to 8” depth

NitrogenNitrogen

N absorption by roots N absorption by roots is driven by demandis driven by demand

Demand is regulated by growth of leaves or fruit, and production of proteins.

Flowers may be Flowers may be aborted if leaf N is aborted if leaf N is deficient the previous deficient the previous summer summer

NitrogenNitrogen

Leaf Concentration: Leaf Concentration: 2.5-3.3% 2.5-3.3%

(Apply when less than (Apply when less than 3) 3)

10 lbs N/100 lbs 10 lbs N/100 lbs expected crop expected crop

Shoot growth should be Shoot growth should be 8-12” 8-12”

NitrogenNitrogen

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.

NitrogenNitrogen General Recommendation:General Recommendation:

75-100 lbs N applied mid-late April75-100 lbs N applied mid-late April Examine Crop in June/JulyExamine Crop in June/July ““On Year”---50 lbs around August 15On Year”---50 lbs around August 15 ““Off Year”---0 lbs around August 15Off Year”---0 lbs around August 15

ORORIF NO AUGUST APPLICATIONIF NO AUGUST APPLICATION 75 lbs N in March/April (March after “on 75 lbs N in March/April (March after “on

year”)year”) 25-75 lbs in late May/Early August25-75 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

NitrogenNitrogenDry-Land /Neglected OrchardsDry-Land /Neglected Orchards 75 lbs N in March75 lbs N in March 25 lbs in late May25 lbs in late MayYoung treesYoung trees Year 1: Year 1: 1 cup ammonium nitrate in June if growth is good 1 cup ammonium nitrate in June if growth is good

(2-4’ terminal (2-4’ terminal growth)growth)

Year 2: Year 2: 1 cup in April, 1 in May, and 1 in June 1 cup in April, 1 in May, and 1 in June Year 3-4:Year 3-4: 2 cups in April, May, and June 2 cups in April, May, and June Year 5-7:Year 5-7: 4 cups in April, May, and June 4 cups in April, May, and June

++ Year 1:Year 1: 1 lb 10-10-10 fertilizer1 lb 10-10-10 fertilizer distributed in a 25 sq. ft. distributed in a 25 sq. ft.

area around the treearea around the tree (apply in June if growth is good)(apply in June if growth is good)

After Year 1:After Year 1: 4 lbs of 10-10-10 fertilizer for each inch of 4 lbs of 10-10-10 fertilizer for each inch of trunk diametertrunk diameter (measured one foot above soil surface). Do (measured one foot above soil surface). Do not place fertilizer within 12 inches of the trunknot place fertilizer within 12 inches of the trunk

1 lb zinc sulfate per tree for the first three years following 1 lb zinc sulfate per tree for the first three years following planting.planting.

NitrogenNitrogen Fertilizing on a per tree basisFertilizing on a per tree basis

Mature treesMature trees 1 lb amm. Nitrate/inch of trunk diameter in late 1 lb amm. Nitrate/inch of trunk diameter in late

March before bud break. Water in promptlyMarch before bud break. Water in promptly If lawn is concern, bore holes in ground and If lawn is concern, bore holes in ground and

pour in, then water areapour in, then water area

++ 4 pounds of 10-10-10 for each inch of trunk 4 pounds of 10-10-10 for each inch of trunk

diameterdiameter (measure 4 1/2 feet above soil level) up to (measure 4 1/2 feet above soil level) up to 25 lbs/tree. This fertilizer should be applied 25 lbs/tree. This fertilizer should be applied in late in late March before bud breakMarch before bud break. Zinc needs are best . Zinc needs are best determined by analysis of leaf samples taken in late determined by analysis of leaf samples taken in late July or early August. (Max 2 lbs/tree)July or early August. (Max 2 lbs/tree)

Clover as a Source of Clover as a Source of NitrogenNitrogen

Crimson – 100 lbs N/ACrimson – 100 lbs N/A 10 lbs/A seeding rate10 lbs/A seeding rate 1.00-1.50/lb1.00-1.50/lb

White Clover--103 lbs White Clover--103 lbs N/AN/A 4 lbs/A seeding rate4 lbs/A seeding rate 2.00-2.50/lb2.00-2.50/lb

Use mixtureUse mixture Allow clover to re-seedAllow clover to re-seed Apply Poast in FebruaryApply Poast in February

Potassium (K)Potassium (K)

K is transported to nuts at leaf’s expenseK is transported to nuts at leaf’s expense 50-100 lbs K applied in February/March 50-100 lbs K applied in February/March During “on” year apply additional 30 lbs K in During “on” year apply additional 30 lbs K in

mid Augustmid August 1.25-2.5 ppm in leaf analysis1.25-2.5 ppm in leaf analysis Manage N/K ratio to 2:1Manage N/K ratio to 2:1 Manage Mg---(No Dolomitic lime above .45% Manage Mg---(No Dolomitic lime above .45%

Mg)Mg) Deficiency most common on Desirable and Deficiency most common on Desirable and

SchleySchley

Basal Leaf ScorchBasal Leaf Scorch Usually occurs in Usually occurs in

June/JulyJune/July Results from imbalance Results from imbalance

between N/Kbetween N/K More susceptible to More susceptible to

winter injurywinter injury DefoliationDefoliation Occurs on basal leaves of Occurs on basal leaves of

shoot and moves upwardshoot and moves upward Scorched areas circular Scorched areas circular

or oblong/ dime sizeor oblong/ dime size

Basal Leaf ScorchBasal Leaf Scorch Maintain adequate K Maintain adequate K

levelslevels

When K level is marginal When K level is marginal or deficient, N level or deficient, N level should be reduced until K should be reduced until K is correctedis corrected

Foliar K can help, but Foliar K can help, but does not replace soil does not replace soil appliedapplied

(Potassium Nitrate: 3 (Potassium Nitrate: 3 lbs/100 gallons)lbs/100 gallons)

ZincZinc Necessary for shoot Necessary for shoot

elongation, leaf elongation, leaf expansion, and yieldexpansion, and yield

Apply when Zn in leaf Apply when Zn in leaf is below 50 ppm is below 50 ppm

2 lbs Zinc sulphate + 2 lbs Zinc sulphate + 3 lbs Potassium 3 lbs Potassium Nitrate/100 gallonsNitrate/100 gallons

Begin 2 wks after Begin 2 wks after budbreak until shoot budbreak until shoot elongation completeelongation complete

Mouse EarMouse Ear Nickel DeficiencyNickel Deficiency Zinc ManagementZinc Management Nickel lignosulfonateNickel 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.

MagnesiumMagnesium 0.35-0.6% leaf 0.35-0.6% leaf Deficiency occurs on Deficiency occurs on

acid soils (pH <5.5)acid soils (pH <5.5) High K or CaHigh K or Ca Use Dolomitic limeUse Dolomitic lime Maintain pH of 6.0-6.5Maintain pH of 6.0-6.5 OK to use calcitic lime OK to use calcitic lime

when Mg above 0.45%when Mg above 0.45% If pH adequate, apply If pH adequate, apply

foliar Magnesium foliar Magnesium Sulfate at 5 lbs/100 Sulfate at 5 lbs/100 gallons (4” shoot growth gallons (4” shoot growth to July)to July)

Chicken LitterChicken Litter Have sample analyzedHave sample analyzed Typically 70 lbs N/ton; Typically 70 lbs N/ton;

35 lbs P; 35 lbs P; 40 lbs K; 40 lbs K; 0.6 Zn0.6 Zn

Nutrients are organically Nutrients are organically boundbound

Organic matter adds Organic matter adds tilth/water-holding capacity tilth/water-holding capacity to soilto soil

Apply between late Apply between late February and early June February and early June

Use BROILER litter and Use BROILER litter and NOT LAYER litterNOT LAYER litter

Ca/MgCa/Mg

Water SplitWater Split Occurs in Occurs in

August/September on August/September on Certain Varieties (late Certain Varieties (late water stage/early shell water stage/early shell hardening)hardening)

Split occurs along ½ Split occurs along ½ length of fruit and may length of fruit and may penetrate shuck and penetrate shuck and shellshell

Rapid influx of waterRapid influx of water Rain/Irrigation/ Rain/Irrigation/

High humidity/Low solar High humidity/Low solar radiationradiation

Water SplitWater Split

Occurs w/in 24 hrs of heavy influx of Occurs w/in 24 hrs of heavy influx of water to soilwater to soil

Most split occurs in upper 1/3 of Most split occurs in upper 1/3 of canopycanopy

Split occurs in pre-dawn hours Split occurs in pre-dawn hours Fruit falls from tree within 7 days of Fruit falls from tree within 7 days of

splittingsplitting

Managing Water SplitManaging Water Split

Maintain soil moisture 2-3 wks Maintain soil moisture 2-3 wks before shell hardening (limited)before shell hardening (limited)

Fruit thinningFruit thinning Avoid excessive NAvoid excessive N Micronutrients?Micronutrients?

B, Ni, CuB, Ni, Cu

Orchard Floor Orchard Floor ManagementManagement Mature TreesMature Trees

Early Spring Pre-EmergenceEarly Spring Pre-Emergence:: SimazineSimazine—2-4 qts/A—2-4 qts/A

Control of Annual Broadleaf weeds Control of Annual Broadleaf weeds and some ann grassesand some ann grasses

Use low rate on sandy soilUse low rate on sandy soilOROR

Surflan 2-4 qts/A + Simazine—2-4 qts/ASurflan 2-4 qts/A + Simazine—2-4 qts/ABroader SpectrumBroader Spectrum

Karmex 2-4 LBSKarmex 2-4 LBSDo Not use on sandy soil; Do not Do Not use on sandy soil; Do not

grazegraze

Spring PostSpring Post: : (Can be mixed with pre-emerge applications) (Can be mixed with pre-emerge applications) Gramoxone Max 1.75-2.7 pts or Boa 2-3 ptsGramoxone Max 1.75-2.7 pts or Boa 2-3 pts

20 GPA Volume improves control20 GPA Volume improves controlAdd 1 gal crop oil /100 gal spray mixAdd 1 gal crop oil /100 gal spray mixBroad Spectrum of Annual weeds Broad Spectrum of Annual weeds

when small and succulentwhen small and succulentDo NOT contact foliage, green bark Do NOT contact foliage, green bark

or allow animals to grazeor allow animals to grazeOROR

PoastPoast 16 oz/A-----Clover release 16 oz/A-----Clover release

Orchard Floor Orchard Floor ManagementManagement

Summer Burndown Herbicides: Summer Burndown Herbicides:

((Do NOT contact foliage or green bark)Do NOT contact foliage or green bark)

Roundup (Glyphosate)Roundup (Glyphosate) 1-2 qts/A1-2 qts/A

OROR Roundup+Karmex 2-4 lbsRoundup+Karmex 2-4 lbs

Use low rate on sandy soilUse low rate on sandy soil

OROR Gramoxone Max 1.75-2.7 ptsGramoxone Max 1.75-2.7 pts

RelyRely 3-6 qts/A3-6 qts/A

Better on perennialsBetter on perennials

Orchard Floor Orchard Floor ManagementManagement

Eliminate grass and weed competition under orchard treesEliminate grass and weed competition under orchard trees Non-Bearing TreesNon-Bearing Trees

Pre-EmergencePre-Emergence ((after soil settlesafter 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 2.4-4.8 qts (after soil settles)Prowl 2.4-4.8 qts (after soil settles) Solicam 2.5-5lbs. (after soil settles)Solicam 2.5-5lbs. (after soil settles)

Post-EmergencePost-Emergence Roundup (Glyphosate)Roundup (Glyphosate) 1-2 qts/A1-2 qts/A Rely (Glufosinate)Rely (Glufosinate) 3 -6 qts/A3 -6 qts/A Poast 16 oz/A Poast 16 oz/A

OROR Fusilade 16 oz/A Fusilade 16 oz/A

1 qt crop oil1 qt crop oillow spray volume (10 GPA) increases activitylow spray volume (10 GPA) increases activity(no broadleaf activity)(no broadleaf activity)

Do NOT contact foliage or green barkDo NOT contact foliage or green bark

Basic Needs of the Pecan Basic Needs of the Pecan CropCrop

LightLight WaterWater Leaf RetentionLeaf Retention Management of Crop Management of Crop

LoadLoad PollinationPollination

Pecan IrrigationPecan Irrigation

71,031 Irrigated Pecan Acres in GA 71,031 Irrigated Pecan Acres in GA (~50% of crop) (~50% of crop)

based on UGA Farm Gate & Irrigation Surveysbased on UGA Farm Gate & Irrigation Surveys Average Amount Applied/Year = 15.5”Average Amount Applied/Year = 15.5” Average Cost/Year = $64.50/AAverage Cost/Year = $64.50/A 18,254 Acres irrigated by solid-set18,254 Acres irrigated by solid-set 52,777 Acres irrigated by drip52,777 Acres irrigated by drip

Irrigation Schedule for Irrigation Schedule for PecansPecans

MONTHMONTH SPRINKLER SPRINKLER DRIPDRIP

Inches/A Inches/A % cycle% cycleAprilApril 0.5” 0.5” 6060MayMay 0.75” 0.75” 7070JuneJune 1” 1” 8080JulyJuly 1.25”1.25” 9090

August August 1.5”1.5” 100100

SeptemberSeptember 1.5” 1.5” 100100OctoberOctober 1” 1” 9090NovemberNovember 0.5”0.5” 6060

PollinationPollination

Desirable (I) – April 23-Desirable (I) – April 23-May 4May 4

Cape Fear (I) – April 22-Cape Fear (I) – April 22-May 4 May 4

Stuart (II) -- April 22-April Stuart (II) -- April 22-April 2929

Sumner (II) -- April 22-Sumner (II) -- April 22-April 28April 28

Elliott (II) – April 19-April Elliott (II) – April 19-April 3030

Schley (II) – April 19-April Schley (II) – April 19-April 2727

Desirable (I) – April 23-Desirable (I) – April 23-April 28April 28

Cape Fear (I) – April 23- Cape Fear (I) – April 23- April 30April 30

Stuart (II) – April 28-May 7Stuart (II) – April 28-May 7 Sumner (II) – May 1-May 7Sumner (II) – May 1-May 7 Elliott (II) – April 27-May 3Elliott (II) – April 27-May 3 Schley (II) – April 23-May Schley (II) – April 23-May

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Pistil Receptivity Pollen Shed