abscission bob ebel. sweet orange production in florida total production: 577,000 acres ...
DESCRIPTION
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 managementTRANSCRIPT
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