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 Fruit Abscission and Leaf Drop in Citrus Cultivars Treated with Metsulfuron-methyl

1999 ◽  
Vol 9 (3) ◽  
pp. 412-416 ◽  
Author(s):  
Walter J. Kender ◽  
Ulrich Hartmond ◽  
Jacqueline K. Burns
Keyword(s):  
Active Ingredient ◽  
Citrus Sinensis ◽  
Citrus Fruit ◽  
Fruit Abscission ◽  
Metsulfuron Methyl ◽  
Fruit Drop ◽  
Valencia Orange ◽  
Leaf Drop

Fruit of 11 citrus cultivars were evaluated for their response to the experimental abscission material metsulfuron-methyl at 2 mg·L-1 (ppm) active ingredient as an aid to mechanical or hand harvest. Cultivars evaluated included `Ambersweet', `Glen Navel', `Hamlin', and `Valencia' oranges [Citrus sinensis (L.) Osb.], `Robinson' tangerine (Clementine × Orlando, C. reticulata Blanco), `Sunburst' tangerine [`Robinson' × `Osceola', C. reticulata × (C. paradisi Macf. × C. reticulata)], `Murcott' and `Temple' tangor (C. reticulata × C. sinensis), `Orlando' tangelo (C. reticulata × C. paradisi), `Ray Ruby', and `Marsh' grapefruit (C. paradisi). Six of the 11 cultivars were effectively loosened by sprays of metsulfuron-methyl (`Hamlin', `Valencia', `Orlando', `Murcott', `Temple', and `Ray Ruby'). Addition of an adjuvant (Kinetic, 0.125%) was necessary for abscission activity in fruit and leaves. Trees sprayed with metsulfuron-methyl in combination with an adjuvant had higher percent cumulative fruit drop, higher internal ethylene, and lower fruit detachment forces (FDF) than trees sprayed with metsulfuron-methyl alone. `Sunburst' tangerine responded poorly to the abscission material in the presence or absence of Kinetic. Leaf loss was greatest in trees sprayed with metsulfuron-methyl and adjuvant, intermediate in trees sprayed with metsulfuron-methyl alone, and least in control trees. Twig dieback was observed in trees of `Valencia' orange and `Marsh' grapefruit sprayed with metsulfuron-methyl. The peel of some cultivars had irregular coloration and developed pitted areas after harvest. Although metsulfuron-methyl is an effective abscission agent for mature citrus fruit, further work is needed to more accurately define conditions for its safe and dependable use.

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 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.

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 Effect of Application Techniques on Abscission Chemical Deposition and Mechanical Harvesting of `Valencia' Oranges

2003 ◽  
Vol 13 (2) ◽  
pp. 344-351
Author(s):  
Muhammad Farooq ◽  
Masoud Salyani ◽  
Jodie D. Whitney
Keyword(s):  
Active Ingredient ◽  
Field Experiments ◽  
Chemical Deposition ◽  
Airflow Rate ◽  
Fruit Removal ◽  
Fluorescent Tracer ◽  
Valencia Orange ◽  
Application Techniques ◽  
The Mean ◽  
The Difference

Field experiments were conducted to investigate the effect of sprayer type, airflow rate, and nozzle output on deposition of active ingredient and mechanical harvesting of `Valencia' orange (Citrus sinensis). Fruit detachment force (FDF) and percentage of fruit removal (PFR) by trunk shaker were used as mechanical harvesting parameters. A PowerBlast sprayer discharging radially and a Titan sprayer discharging over the entire canopy were used. The spray mixture contained an abscission chemical (CMN-pyrazole), a surfactant (Kinetic) and a fluorescent tracer (Pyranine-10G). Deposition was determined at three different heights outside and inside of the canopy. With the PowerBlast, higher airflow and lower nozzle output reduced deposition of the active ingredient. The mean FDF of sprayed treatments was less than that of the non-sprayed control but the difference among the four spray treatments was not significant. The lower airflow rate with lower nozzle output had higher PFR than that of the control. With the Titan sprayer, the mean deposition at lower airflow was similar to or higher than the higher airflow. At higher airflow, the lower nozzle output gave higher mean deposition. The Titan sprayer treatments resulted in less FDF than the control. At both airflow rates, the FDF was less at lower nozzle output than at higher nozzle output. The PFR of these treatments were not different from that of control.

Real-life Field Studies of the NOx Removing Properties of Photocatalytic Surfaces in Roskilde and Copenhagen Airport, Denmark

2020 ◽  
Vol 01 ◽  
Author(s):  
Henrik Jensen ◽  
Pernille D. Pedersen
Keyword(s):  
Air Quality ◽  
High Stability ◽  
Reference Site ◽  
Real Life ◽  
Field Studies ◽  
The Real ◽  
Before And After ◽  
Parking Lot ◽  
Photocatalytic Concrete

Aims: To evaluate the real-life effect of photocatalytic surfaces on the air quality at two test-sites in Denmark. Background: Poor air quality is today one of the largest environmental issues, due to the adverse effects on human health associated with high levels of air pollution, including respiratory issues, cardiovascular disease (CVD), and lung cancer. NOx removal by TiO2 based photocatalysis is a tool to improve air quality locally in areas where people are exposed. Methods: Two test sites were constructed in Roskilde and Copenhage airport. In Roskilde, the existing asphalt at two parking lots was treated with TiO2 containing liquid and an in-situ ISO 22197-1 test setup was developed to enable in-situ evaluation of the activity of the asphalt. In CPH airport, photocatalytic concrete tiles were installed at the "kiss and fly" parking lot, and NOx levels were continuously monitored in 0.5 m by CLD at the active site and a comparable reference site before and after installation for a period of 2 years. Results: The Roskilde showed high stability of the photocatalytic coating with the activity being largely unchanged over a period of 2 years. The CPH airport study showed that the average NOx levels were decreased by 12 % comparing the before and after NOx concentrations at the active and reference site. Conclusion: The joined results of the two Danish demonstration projects illustrate a high stability of the photocatalytic coating as well as a high potential for improvements of the real-life air quality in polluted areas.

RATIONALE FOR MONITORING GROUNDWATER LEVELS IN THE REHABILITATED PEATLANDS OF PRIPYAT POLESIE

2020 ◽  
pp. 33-43
Author(s):  
Olga N. Ratnicava ◽  
Irina P. Lisitsyna ◽  
Inna V. Аgeichik
Keyword(s):  
Field Studies ◽  
Natural State ◽  
Groundwater Levels ◽  
Discharge Water ◽  
Peat Deposits ◽  
Disturbed Areas ◽  
Key Points ◽  
Before And After ◽  
Vegetation Maps ◽  
Relationship Of

Based on studies of geomorphology, stratigraphy, hydrology, various maps of Polesie, zones of influence of amelioration canals, vegetation maps, modern satellite images, as well as field studies of peatlands of Pripyat Polesie, two independent drainage systems have been identified, with a network of amelioration canals that intensively discharge water into the rivers Stwiga and Ybort`. Maps of key points were built In GIS-format, on which five sites were laid in the field within the Mezhch and Neresnya peat deposits for further long-term monitoring of GWL parameters. The locations of the sensors installation are based on the relationship of bog phytocenoses with the average annual GWL values and the amplitude of their fluctuations. Analysis of the GWL parameters before and after environmental rehabilitation measures will allow assessing the effectiveness of planned measures in disturbed areas and obtaining new data on areas of peat deposits in their natural state.

Traffic Flow Characteristics on a Three-Lane Rural Highway in Finland: Results from Empirical Studies and Simulations

1997 ◽  
Vol 1572 (1) ◽  
pp. 33-42 ◽  
Author(s):  
Åsa Enberg ◽  
Matti Pursula
Keyword(s):  
Traffic Flow ◽  
Flow Rate ◽  
Empirical Studies ◽  
Flow Characteristics ◽  
Field Studies ◽  
Optimum Length ◽  
Before And After ◽  
Traffic Flow Characteristics ◽  
Simulation Results ◽  
Rural Highway

The traffic-flow characteristics on an experimental, 20-km-long three-lane highway section in Finland were studied. The sections of highway that have a separate passing lane consist of three lanes. The central lane is assigned alternately to each direction as a passing lane with a length of 1.05 to 1.70 km. The lengths of the no-overtaking zones between successive passing lanes are 1.5 to 4.0 km. The traffic-flow characteristics on the three-lane highway have been observed by comprehensive before-and-after field studies and complementary simulations. Because it was possible to use passing lanes, the number of overtakings on the three-lane highway was remarkably higher than on the former two-lane highway. The overall average travel speeds were slightly higher, and the speed decreased a little more slowly with increasing flow on the three-lane compared with the two-lane highway. Overall platooning and mean platoon lengths decreased as a result of platoon dispersal on the passing lanes. The speeds used in the passing lanes were clearly higher than in the basic lanes. According to the simulation results, the optimum length for a single passing lane was between 0.5 and 2.5 km depending on flow rate and measure of effectiveness. For the actual three-lane highway conditions, passing lanes 1.0 to 1.5 km long seemed to bring the most benefits.

Sethoxydim and Crop Oil Concentrate Increase Pyridate Phytotoxicity in Transplanted Cabbage (Brassica oleracea)

1997 ◽  
Vol 11 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Robin R. Bellinder ◽  
Jonathan Kirkwyland ◽  
Russell W. Wallace ◽  
Marija Arsenovic
Keyword(s):  
Brassica Oleracea ◽  
Dry Weight ◽  
Field Studies ◽  
Crop Injury ◽  
Before And After

Greenhouse and field studies were conducted in 1991 and 1992 to determine the potential for interaction among pyridate (0.5, 1.0 kg ai/ha), sethoxydim (0.22 kg ai/ha), and crop oil concentrate (COC) (1.25% v/v) applied alone or in two- and three-way combinations to transplanted cabbage. Additionally, the effect of applying sethoxydim and COC 1 and 2 d before and after application of pyridate was investigated. In greenhouse-grown cabbage, injury increased twofold and dry weight was reduced 15% when pyridate dose was doubled. Sethoxydim increased pyridate injury significantly, reducing dry weight 31%. When COC was applied with pyridate, injury increased and dry weight decreased linearly. Despite substantial crop injury 7 d after treatment with pyridate alone, pyridate + sethoxydim, and pyridate + COC, yields of field-grown cabbage were reduced significantly in 1 yr only when the three materials were combined. Pyridate injury decreased as time between sethoxydim + COC applications, before and after pyridate was applied, increased.

Fluazifop-P Tank-Mixtures with Clethodim for Annual Grass Control in Flax (Linum usitatissimum)

1994 ◽  
Vol 8 (4) ◽  
pp. 673-678 ◽  
Author(s):  
David A. Wall
Keyword(s):  
Weed Control ◽  
Active Ingredient ◽  
Linum Usitatissimum ◽  
Field Studies ◽  
Wild Oat ◽  
Annual Grass ◽  
Foliar Injury ◽  
Leaf Stage ◽  
Green Foxtail

Field studies were undertaken in 1992 and 1993 to investigate the control of wild oat and green foxtail in flax with reduced rates of fluazifop-P and clethodim applied as tank-mixtures. Fluazifop-P plus clethodim at 50 + 18 g ai/ha controlled wild oat and green foxtail and was as effective as full rates of either herbicide applied alone. These rates represent a 20% reduction in total amount of active ingredient required to control wild oat and green foxtail. Application of fluazifop-P, and/or clethodim prior to the 3- to 4-leaf stage failed to control late emerging grass weeds. Application of graminicide mixtures at or after the 3- to 4-leaf stage controlled late emerging grass weeds and did not affect flax yield. When applied late, fluazifop-P at 175 g/ha tended to reduce flax yield, although weed control was acceptable and no foliar injury was observed following treatment. The efficacy of graminicide mixtures was reduced by addition of bromoxynil plus MCPA to the spray mix.

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