scholarly journals Late-season `Valencia' Orange Mechanical Harvesting with an Abscission Agent and Low-frequency Harvesting

HortScience ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 660-663 ◽  
Author(s):  
Jacqueline K. Burns ◽  
Fritz M. Roka ◽  
Kuo-Tan Li ◽  
Luis Pozo ◽  
Richard S. Buker
Keyword(s):  
Citrus Sinensis ◽  
Low Frequency ◽  
Mature Fruit ◽  
Fruit Removal ◽  
Immature Fruit ◽  
Late Season ◽  
Valencia Orange ◽  
Significant Difference ◽  
Orange Trees

An abscission agent (5-chloro-3-methyl-4-nitro-1H-pyrazole [CMNP]) at 300 mg·L–1 in a volume of 2810 L·ha–1 was applied to Valencia orange trees [Citrus sinensis (L.) Osb.] on 22 May 2004. At this time, immature and mature fruit were present on the tree simultaneously. Three days after application, fruit were mechanically harvested using a trunk-shake-and-catch system. The power to the shaker head was operated at full- or half-throttle (FT or HT, respectively), and the duration of trunk shaking was 2 seconds at FT or 4 seconds at FT and HT. Mature fruit removal percentage and number of immature fruit removed, and fruitlet weight and diameter were determined. Mature fruit removal percentage with 2 seconds at FT or 4 seconds at FT harvesting ±CMNP, or 4 seconds at HT + CMNP was not significantly different and ranged between 89% to 97%. Harvesting at 4 seconds HT without CMNP removed significantly less mature fruit than any treatment. CMNP did not affect immature fruit removal by the trunk shaker. Harvesting at 4 seconds at HT removed significantly less immature fruit than 2 seconds at FT or 4 seconds at FT. No significant difference in fruitlet weight or diameter was measured between any trunk shaker harvest operation and CMNP treatment. Trunk shaking frequency was estimated to be 4.8 and 8.0 Hz at HT and FT, respectively. Yield in 2005 was determined on the same trees used for harvest treatments in 2004. CMNP did not impact yield. No significant difference in yield was seen between the hand-picked control and 4 seconds at HT, whereas yield in the remaining treatments was lower. The results demonstrate that CMNP application combined with low frequency trunk shaker harvesting can achieve high percentage of mature fruit removal with no significant impact on return yield of the following crop.

scholarly journals Mechanical Harvesting Capacity in Sweet Orange Is Increased with an Abscission Agent

2005 ◽  
Vol 15 (4) ◽  
pp. 758-765 ◽  
Author(s):  
Jacqueline K. Burns ◽  
Richard S. Buker ◽  
Fritz M. Roka
Keyword(s):  
Short Duration ◽  
Citrus Sinensis ◽  
Sweet Orange ◽  
Mature Fruit ◽  
Fruit Removal ◽  
Ground Speed ◽  
Detachment Force ◽  
Fruit Drop ◽  
Valencia Orange ◽  
Significant Difference

An abscission agent [5-chloro-3-methyl-4-nitro-1H-pyrazole (CMNP)] was applied to `Hamlin' and `Valencia' orange (Citrus sinensis) trees at concentrations ranging from 0 to 500 ppm in a volume of 300 gal/acre. Four days after application, fruit were mechanically harvested with either a trunk shake-and-catch or a continuous canopy shake-and-catch system commercially used in Florida. Harvesting conditions were varied by limiting the actual trunk shake time of the trunk shaker to 2, 4, or 7 seconds, or by altering the ground speed of the canopy shaker (1.0, 1.5, or 2.0 mph). In general, increasing duration of shake and the application of CMNP increased percent mature fruit removal and decreased the amount of fruit remaining in the tree. Increasing CMNP concentration decreased fruit detachment force but increased post-spray fruit drop. Comparison of short duration shake times in CMNP-applied trees with trees harvested at longer durations either sprayed or not sprayed with CMNP indicated no significant difference in percent mature fruit removal. The results demonstrate that CMNP application increases harvesting capacity of trunk and canopy shakers by reducing time necessary to harvest each tree while maintaining high percent mature fruit removal.

Effect of time of harvest on alternate cropping yields and fruit quality of Valencia orange trees

1978 ◽  
Vol 18 (92) ◽  
pp. 461 ◽  
Author(s):  
PT Gallasch
Keyword(s):  
Fruit Quality ◽  
South Australia ◽  
Mature Fruit ◽  
Late Season ◽  
Valencia Orange ◽  
The Common ◽  
Orange Trees ◽  
Early Harvest ◽  
Time Of Harvest

At Loxton, South Australia, early harvest of heavy, and late harvest of light, Valencia orange crops was compared with the common practice: early harvest of light and late harvest of heavy crops. These treatments were compared with two years of early, mid- or late season harvests. Early harvest of heavy and late harvest of light crops changed the 3.1:1.0 alternate cropping cycle to 1.1:10 and increased the light crop by 101 per cent compared with the common district practice which gave a 3.2 : 10 cycle. Consistent early and mid-season harvests reduced the alternate cropping ratio to 1.3 : 1.0 and 1.4 : 1.0 respectively, produced 14 per cent more fruit than the common district practice and avoided harvesting the light crop late, when fruit quality is poor. Mature fruit weights from trees consistently harvested late were 27 per cent lower than those trees harvested mid-season.

scholarly journals Optimizing Continuous Canopy Shakers for Late Season `Valenica' Harvest

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 885A-885
Author(s):  
Richard S. Buker* ◽  
Jackie K. Burns ◽  
Fritz M. Roka
Keyword(s):  
Operating Conditions ◽  
Tree Size ◽  
Mature Fruit ◽  
Fruit Removal ◽  
Crop Load ◽  
Immature Fruit ◽  
Late Season ◽  
Southern Site ◽  
Mechanical Harvester

Continuous canopy shakers (CCS) were developed in the late 90's and have been used to commercially harvest citrus in Florida. A viable mechanical harvester in Florida must be able to selectively remove mature `Valencia' fruit. A study was conducted to evaluate the effect of operating conditions on mature and immature fruit removal during the 2003 harvest season. The study was conducted in the southern flat woods and northern ridge areas. The study treatments were completely random and replicated four times. The CCS treatments were 145, 215, 230, and 245 cycles per minute (cpm) and a hand picked control. The harvest occurred on 17 and 19 June at the southern and northern sites, respectively. Mature fruit removal linearly increased from 95.7% to 97.9% between 145 and 245 cpm, respectively. Varying the operating ranges significantly influenced mature fruit removal in the southern flat woods site. The trees at the southern site were taller (>4m), and had a larger crop load. At the northern ridge site where trees were smaller, varying the CCS operating ranges did not significantly influence mature fruit removal. Immature fruit removal was influenced by the operating ranges. Immature fruit removal was increased at least 22% over hand picked controls. The results were interpreted to indicate the frequency of CCS is dependent on tree size. The initial selectivity of the CCS was not equal to hand picking.

scholarly journals Guanfacine and Clonidine Reduce Defoliation and Phytotoxicity Associated with Abscission Agents

2003 ◽  
Vol 128 (1) ◽  
pp. 42-47 ◽  
Author(s):  
Jacqueline K. Burns ◽  
Luis V. Pozo ◽  
Rongcai Yuan ◽  
Brandon Hockema
Keyword(s):  
Butyric Acid ◽  
Phosphonic Acid ◽  
Tree Species ◽  
Citrus Sinensis ◽  
Prunus Persica ◽  
Continuous Exposure ◽  
Immature Fruit ◽  
Metsulfuron Methyl ◽  
Valencia Orange ◽  
Vegetative Cuttings

Guanfacine and clonidine were combined with ethephon or metsulfuron-methyl in the spray tank and applied as foliar sprays to Citrus sinensis L. Osb. `Valencia', Citrus madurensis Loureiro (calamondin), and Prunus persica `Elberta' to determine their effects on leaf loss, fruit detachment force (FDF), immature fruit loss, and twig dieback. In `Valencia' orange, `Elberta' peach and calamondin, guanfacine and clonidine effectively reduced ethephon-induced defoliation in all three tree species, whereas only guanfacine was effective with metsulfuron-methyl applications in `Valencia'. The ability of ethephon to reduce FDF in `Valencia' was only minimally impaired by guanfacine but not impaired by clonidine. Both guanfacine and clonidine diminished the capacity of metsulfuron-methyl to reduce FDF. Guanfacine reduced immature fruit loss of `Valencia' caused by metsulfuron-methyl and reduced twig-dieback. Leaf loss was reduced whether guanfacine or clonidine were applied with ethephon, or 24 hours or 17 days before ethephon application. Guanfacine and clonidine reduced leaf loss induced by continuous exposure of potted calamondin trees to ethylene, and leaf loss was similar with guanfacine and 1-methylcyclopropene (1-MCP) treatments. In separate experiments, guanfacine and clonidine were unable to block ethylene perception in Arabidopsis seedlings and petunia flowers but promoted rooting in coleus and tomato vegetative cuttings, suggesting that these compounds have auxin-like activity. The results demonstrate the potential to enhance selectivity of abscission agents with guanfacine and clonidine. Chemical names used: 2-[(2,6-dichlorophenyl)amino]-2-imidazoline, clonidine; 5-chloro-3-methyl-4-nitro-pyrazole, CMN-P; [(2,6-dichlorophenyl)acetyl]guanidine, guanfacine; [(2-chloroethyl)phosphonic acid, ethephon; indole-3-butyric acid, IBA; 1-methylcyclopropene, 1-MCP.

scholarly journals Seasonal Variation in the Response of `Valencia' Orange to Two Abscission Compounds

HortScience ◽  
2000 ◽  
Vol 35 (2) ◽  
pp. 226-229 ◽  
Author(s):  
U. Hartmond ◽  
J.D. Whitney ◽  
J.K. Burns ◽  
W.J. Kender
Keyword(s):  
Seasonal Variation ◽  
Active Ingredient ◽  
Citrus Sinensis ◽  
Field Studies ◽  
Separate Experiment ◽  
Fruit Removal ◽  
Metsulfuron Methyl ◽  
Valencia Orange ◽  
Leaf Drop ◽  
Before And After

Two field studies were conducted to evaluate the effect of metsulfuron-methyl and 5-chloro-3-methyl-4-nitro-1H-pyrazole (CMN-pyrazole) on abscission of `Valencia' orange [Citrus sinensis (L.) Osbeck] during the 3-month harvest season. Solutions of metsulfuron-methyl at 0.5, 1, and 2 mg·L-1 active ingredient (a.i.) were applied at 10-day intervals beginning on 13 Feb. and ending 18 May 1998. Early in the harvest season, 1 or 2 mg·L-1 metsulfuron-methyl significantly reduced fruit detachment force (FDF) 14 days after application. Metsulfuron-methyl was less effective during a 4- to 6-week period following bloom (“less-responsive period”). After this period, metsulfuron-methyl regained the ability to loosen fruit. Applications of 2 mg·L-1 a.i. were more effective than 1 mg·L-1 in reducing FDF and causing leaf drop, but 0.5 mg·L-1 a.i. had little or no effect on FDF. Flowers and leaflets on developing shoots and young fruit completely abscised with 1 and 2 mg·L-1 a.i. Defoliation and twig dieback was extensive at all concentrations and spray dates, eliminating metsulfuron-methyl as a commercially viable abscission agent for citrus. In a separate experiment CMN-pyrazole at 50 and 100 mg·L-1 a.i. and metsulfuronmethyl at 0.5 mg·L-1 a.i. were applied to `Valencia' trees to determine fruit removal with a trunk shake and catch harvesting system. Application of both abscission materials before and after the “less-responsive period” resulted in a 10% to 12% increase in fruit removal when compared to control trees. Less than a 35% reduction in FDF was sufficient to significantly increase fruit removal. Only 100 mg·L-1 a.i. CMN-pyrazole significantly increased fruit removal when applied during the “less-responsive period.” Chemical names used: Methyl-2-(((((4-Methoxy-6-Methyl-1,3,5-Triazin-2-yl)-Amino)Carbonyl) Amino)Sulfonyl)Benzene (Metsulfuron-methyl); 5-Chloro-3-methyl-4-nitro-1-H-pyrazole (CMN-pyrazole).

scholarly journals Coronatine and Abscission in Citrus

2003 ◽  
Vol 128 (3) ◽  
pp. 309-315 ◽  
Author(s):  
Jacqueline K. Burns ◽  
Luis V. Pozo ◽  
Covadonga R. Arias ◽  
Brandon Hockema ◽  
Vidhya Rangaswamy ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Syringae ◽  
Ethylene Production ◽  
Citrus Sinensis ◽  
Acid Oxidase ◽  
Mature Fruit ◽  
Chlorophyll Contents ◽  
Coronafacic Acid ◽  
Valencia Orange ◽  
Orange Fruit

Coronatine is a polyketide phytotoxin produced by several plant pathogenic Pseudomonas spp. The effect of coronatine on abscission in Citrus sinensis L. Osbeck `Hamlin' and `Valencia' orange fruit, leaves, fruitlets, and flowers was determined. Coronatine at 200 mg·L-1 significantly reduced fruit detachment force of mature fruit, and did not cause fruitlet or flower loss in `Valencia'. Cumulative leaf loss was 18% with coronatine treatment. Coronafacic acid or coronamic acid, precursors to coronatine in Pseudomonas syringae, did not cause mature fruit abscission. Ethylene production in mature fruit and leaves was stimulated by coronatine treatment, and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) and 12-oxo-phytodienoate reductase (12-oxo-PDAR) gene expression was upregulated. A slight chlorosis developed in the canopy of whole trees sprayed with coronatine, and chlorophyll content was reduced relative to adjuvant-treated controls. Leaves formed after coronatine application were not chlorotic and had chlorophyll contents similar to controls. Comparison of coronatine to the abscission compounds methyl jasmonate, 5-chloro-3-methyl-4-nitro-pyrazole and ethephon indicated differences in ethylene production and ACO and 12-oxo-PDAR gene expression between treatments. Leaf loss, chlorophyll reduction and low coronatine yield during fermentation must be overcome for coronatine to be seriously considered as an abscission material for citrus.

Fruit Removal and Continual Defoliation Altered Papaya Fruit Production and Quality

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 497e-497
Author(s):  
Lili Zhou ◽  
David Christopher ◽  
Robert E. Paull
Keyword(s):  
Fruit Set ◽  
Sugar Content ◽  
Fruit Size ◽  
Sugar Accumulation ◽  
Sink Strength ◽  
Mature Fruit ◽  
Fruit Removal ◽  
Control Fruit ◽  
Significant Difference ◽  
Fruit Mass

The source size and sink strength were modified by continual defoliation and fruit removal in `Sunset' papaya. Flower and fruit set, mature fruit mass, and TSS was recorded weekly. Fruit at four different stages of development were harvested at the end of the experiment. Fruit mass, respiration, sugar content, and sucrose phosphate synthase (SPS), sucrose synthase (SS), and invertase enzyme activities were compared. Continual defoliation resulted in lower new fruit set (25% of control), smaller fruit size (77% of control), and lower TSS (85% of control) in the 24-week experimental period. In contrast, there were 52% and 100% more new fruit when fruit were removed than in the control within the first 8 weeks and 24 weeks, respectively. Larger fruit size, earlier fruit development, lower respiration, and higher sugar contents were observed when fruit were removed at 140, 154, and 175 days from anthesis. No significant difference was found in TSS level in the mature fruit compared to the control. Fruit removal plus defoliation gave the same number and mass of new fruit as the control and slightly lower TSS in mature fruit than in the control. Fruit sugar was higher with increased fruit invertase activity and fruit age. Data confirmed that source–sink balance was critical for fruit set, development, and sugar accumulation in papaya.

Attempts to control alternate cropping of Valencia orange by inhibiting flower formation with gibberellic acid

1978 ◽  
Vol 18 (91) ◽  
pp. 309 ◽  
Author(s):  
PT Gallasch
Keyword(s):  
Gibberellic Acid ◽  
No Reduction ◽  
South Australia ◽  
Flower Formation ◽  
Mature Fruit ◽  
Mature Trees ◽  
Valencia Orange ◽  
Orange Trees

Gibberellic acid (GA) was sprayed on whole Valencia orange trees in 1971 at Loxton in South Australia with the aim of reducing the size of the heavy crop and the alternate cropping cycle. Sprays were applied in June or July at 25 p.p.m. but there was no reduction in mature fruit weights in 1972. In 1973, sprays of GA at 25 p.p.m, were applied twice, about two weeks apart, commencing on either May 7 or 22. In the following November treated trees had 75 per cent fewer fruitlets, but by the time fruit were mature, trees had fully compensated for this early reduction in fruit numbers by increased set and reduced December drop. Again the weight of mature fruit was not reduced at the timings and concentrations used and hence GA cannot be recommended for the control of alternate cropping.

scholarly journals 179 Impact of Rootstock on Maturity and Storage of Valencia Orange Fruits

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 421D-421
Author(s):  
M.M. Khattab ◽  
A.A. Elezaby ◽  
S. ElOraby ◽  
A.M. Hassan
Keyword(s):  
Citrus Sinensis ◽  
Poncirus Trifoliata ◽  
Maturity Stage ◽  
Full Bloom ◽  
Valencia Orange ◽  
Volkamer Lemon ◽  
Orange Trees ◽  
And Storage ◽  
Cleopatra Mandarin ◽  
Troyer Citrange

This investigation was carried out on 13-year-old Valencia orange trees [Citrus sinensis (L.) Osbeck] budded on five different rootstocks. Heat unit accumulation (temperature above 12.5 °C) for fruits worked on the various rootstocks were calculated from full bloom to maturity stage. Valencia fruits on Troyer citrange (C. sinensis × Poncirus trifoliata) and Carrizo citrange (C. sinensis × Poncirus trifoliata) rootstocks matured earlier when compared to those growing on Cleopatra mandarin (C. reticulata Blanco), Volkamer lemon (C. volkameriana Ten. and Pasq.), and sour orange (C. aurantium) rootstocks. The results showed that the Valencia fruits, regardless of rootstock, could be stored for different periods under different conditions. However, in order to avoid degradation in fruit quality, storing periods should not exceed 21, 60, and 120 days under room conditions (25 °C and RH 25% to 35%), 4 °C (RH 80% to 85%), and 8 °C (RH 80% to 85%); respectively.

Sign in / Sign up

Export Citation Format

Share Document