Abscission Bob Ebel

SWEET ORANGE PRODUCTION IN FLORIDA

Total production: 577,000 acres

Mechanically harvested: 35,000 acres ( 7%)

Hand harvested: 552,000 acres (93%)

REASONS FOR COMMERCIAL INTEREST IN MECHANICAL HARVESTING

Labor availability• Traditionally difficult to obtain good labor• Especially late in harvest season (May and June)

due to hot, humid weather

Liability of hiring illegal labor

Labor cost: H2A program

Labor management

ABSCISSION AGENTS

Improve efficiency of current harvester systems

Currently removing only about 75-85% of fruit with canopy shakers

Best: CMNP (5-Chloro-3-Methyl-4-Nitro-1H-Pyrazole)

Experiment Use Permit (EUP) Estimated submission by end 3Q 2009 with EPA EPA review time: about 18 months

Section 3 (Full registration) Estimated submission by end 3Q 2010 EPA review time: 24 months

CURRENT RESEARCH

Limited to 10 acres due to EPA regulations

Two major sets of field trials (Dec. through June)

Objectives:

1. Determine the relationship between CMNP concentration and mechanical harvester setting

2. Develop a predictive model for fruit loosening by CMNP

CMNP and Mechanical Harvester Setting Studies

APPROACH

1.Repeat same treatments on multiple dates Hamlin: mid Dec., early Jan., late January Valencia: mid March, mid April

2.Treatments CMNP: 0, 200, and 300 ppm at 300 gal/acre Pull behind canopy shaker settings: 180, 220, 260

cycles per minute (cpm)

3.Experimental design: RCBD with 4 blocks, and 3 trees per block Harvester setting as the main plot CMNP treatment as the split plot

Fruit loosening requires direct contact with CMNP

Vertical, multi-fan sprayer

Height: no effect on FDFDepth:

• inside: 13.6 lbs• outside: 12.4 lbs

Data Collection

Fruit detachment force (FDF)

Preharvest Drop

Harvested with a “pull-behind” canopy shaker

Harvest data collectionHarvest weight

Glean weight

0200 ppm300 ppm

Early January

Fruit Detachment Force (lbs)

0 5 10 15 20

Valencia

Early December

Mid March

Mid April

Fruit Detachment Force

Hamlin

Late January

CMNP 0CMNP 200CMNP 300

Canopy shaker head speed (cpm)180 220 260

Rem

oval

(%)

50

60

70

80

90

100

Fruit removal by CMNP‘Hamlin’

EarlyJanuary

CMNP by canopy shaker head speed interaction significant

Fruit removal by CMNP‘Valencia’

Canopy shaker head speed (cpm)180 220 260

Rem

oval

(%)

70

75

80

85

90

95

100

CMNP 0CMNP 200CMNP 300

EarlyApril

CMNP by canopy shaker head speed interaction significant

CONCLUSIONS

The benefit of CMNP increases with slower mechanical harvester setting.

Lower shake rate will help alleviate concerns on tree injury by grove managers.

CMNP is beneficial throughout most of the harvest season

CMNP and Mechanical Harvester Setting Studies

CMNP Predictive Model

GOAL

To develop a predictive model for loosening sweet oranges by CMNP that would aid scheduling of CMNP and mechanical harvesting.

Factors that may affect CMNP

CMNP concentration – assume complete coverage to drip Environmental factors

• Rain – not within first 24 hrs after application • Air temperature – highly sensitive – temperatures < 60F slow rate of loosening• Drought – don’t think so• Drying rate

Tree factors• Cultivar and Rootstock• Tree health

Timing• Time of year • Time of day

Hamlin Treatments

Irrigation withheld 5, 12, 19 days in late Jan. CMNP: 250 ppm, 300 gal/acre

Results Stem water potential (MPa) : -1.3a, -1.7b, -1.6b Interaction of CMNP x drought not significant

Valencia Treatments

Irrigation withheld 0, 4, 7 days in late April CMNP: 250 ppm, 300 gal/acre

Results Stem water potential (MPa) : -1.5c, -2.0b, -2.5a Interaction of CMNP x drought not significant

Drought effects on CMNP efficacy (2008)

Effect of air temperature on fruit loosening

Air Temperature (oC)

5 10 15 20 25 30

Frui

t det

achm

ent f

orce

(N)

0

20

40

60

80

100

120y=89.2393+0.1003xr2 = 0.0891ns

y=15,3557+71.121/(1+e-((x-16.2074)/1.2948))0.9383

r2 = 0.9999**70oF60oF

10-year average air temperature, Immokalee

Month

Air

Tem

pera

ture

(o C)

-5

0

5

10

15

20

25

30

December January February March April

10-year average

CURRENT STATUS OF THE MODEL

Must assume complete coverage within the canopy

300 ppm

Hours after application

0 24 48 72 96 120 144

FDF

(lbs)

1

3

5

7

9

11

13Predicted FDFMeasured FDF

Accurately predicts at 300 ppm CMNP

Need to modify at lower concentrations of CMNP

Is independent of short term drought stress

‘Hamlin’ seems to loosen faster than ‘Valencia’ Don’t know whether rootstock has an effect.

Other factors?

Studies planned for 2009-2010

1. Determine the relationship between CMNP concentration and removal by days after application

2. Develop a predictive model for fruit drop by CMNP

Hours after application

0 24 48 72 96 120

Frui

t dro

p (%

)

010203040506070

'Hamlin'12/19/08300 ppm

GOAL: Put the models on FAWN as aids to CMNP and mechanical harvester scheduling

Acknowledgements

Harvest Council

COMMERCIAL COMPANIES

OXBO International AgroSource Barron-Collier Partnership Mutual Harvesting Barben Fruit Everglades Harvesting Silverstrand Gulf Harvest Valencia Harvesting

IFAS/SWFREC

Mr. Peter Newman Dr. Kelly Morgan Dr. Fritz Roka

IFAS/CREC

Dr. Jackie Burns Dr. Tim Spann Dr. Michelle Danyluk

Thank you