Regulating Valencia orange crops with CEPA (2-chloroethyl phosphonic acid) - preliminary studies

1974 ◽  
Vol 14 (71) ◽  
pp. 835 ◽  
Author(s):  
T GallaschP
Keyword(s):  
Phosphonic Acid ◽  
South Australia ◽  
Fruit Yield ◽  
Leaf Fall ◽  
Mature Fruit ◽  
Phytotoxic Effects ◽  
Valencia Orange

The effects of chemicals on fruitlet thinning of Valencia oranges were studied in two experiments at Loxton, South Australia. In the first experiment 50 p.p.m. 245T, 2000 p.p.m. N.A.A. and 250 or 1000 p.p.m. CEPA all caused significant thinning but 245T had phytotoxic effects. In the second experiment with several concentrations of CEPA, both 524 and 1048 p.p.m. caused significant leaf and fruitlet drop, whereas 262 p.p.m. caused a significant reduction of 55 per cent in mature fruit yield without any significant leaf fall.

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.

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.

Control of alternate cropping of Valencia orange with ethephon and napthalene acetic acid

1978 ◽  
Vol 18 (90) ◽  
pp. 152 ◽  
Author(s):  
PT Gallasch
Keyword(s):  
Acetic Acid ◽  
South Australia ◽  
Fruit Weight ◽  
Mature Fruit ◽  
Crop Load ◽  
The Third ◽  
Load Following ◽  
Valencia Orange ◽  
Leaf Drop ◽  
Orange Trees

Three experiments were done in the Riverland district of South Australia with the aim of controlling alternate cropping of mature Valencia orange trees by chemical thinning. In experiment 1, 300 p.p.m. ethephon was applied in either October, November or December. In experiment 2, sprays of either 200, 250, 300 or 350 p.p.m. ethephon were applied in late November. In experiment 3, sprays of either ethephon, NAA or a mixture of both were applied in early December. Sprays of ethephon in December were more effective than in October, and resulted in a 40 per cent reduction of mature fruit weight in a heavy crop year. All concentrations of ethephon of 250 p.p.m, or more reduced the heavy crop load, and in the following year increased light crops. A 15 per cent reduction in crop load following sprays of 250 p.p.m, gave even cropping trees. Treated trees produced, over two years, 10 per cent more fruit weight than control trees. Fruit from treated trees were larger in the heavy crop year and smaller the following year. In the third experiment, 300 p.p.m. ethephon reduced the mature crop by 31 per cent and 500 p.p.m. NAA reduced it by 18 per cent. A mixture of the two chemicals effected a 51 per cent reduction in crop load, but the NAA did not significantly reduce leaf drop. NAA at 500 p.p.m. resulted in the most even cropping trees.

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.

Thinning of cling peaches with ethephon in the Riverland area of South Australia

1981 ◽  
Vol 21 (110) ◽  
pp. 354 ◽  
Author(s):  
FJ Gathercole
Keyword(s):  
South Australia ◽  
Optimum Concentration ◽  
Leaf Fall ◽  
Full Bloom

An ethephon spray 39 to 53 days after full bloom effectively thinned both Golden Queen and Wight peaches in 1973 and 1974, and Wight and Keimos cultivars in 1975, but gave inconsistent results in commercial demonstrations in 1976. The optimum concentration was 40-100 ppm and depended on the degree of thinning needed. Concentrations in this range did not cause any leaf fall but increased the amount of gumming and stone splitting in Golden Queen fruit in 1974; there were no other detrimental effects on the fruit. Uneven thinning between and within trees of Keimos was a problem in 1975.

scholarly journals DENSELY PLANTED OKRA FOR DESTRUCTIVE HARVEST

HortScience ◽  
1995 ◽  
Vol 30 (3) ◽  
pp. 438a-438
Author(s):  
Yaying Wu ◽  
Brian A. Kahn ◽  
John B. Solie
Keyword(s):  
Plant Density ◽  
Fruit Weight ◽  
High Density ◽  
Fruit Yield ◽  
Abelmoschus Esculentus ◽  
Mature Fruit ◽  
Marketable Yield ◽  
Harvest Timing ◽  
Plant Arrangement ◽  
Marketable Fruit

We are developing a mechanical harvest system for okra [Abelmoschus esculentus (L.) Moench]. Our objective was to identify a high-density (HD) plant arrangement and a harvest timing that would maximize marketable fruit yield per hectare with a destructive harvest. We compared destructively harvested plants grown at spacings of (in cm) 15 × 15, 23 × 23, and 30 × 30 with hand-harvested plants grown at 90 × 23 cm. Within HD treatments, marketable fruit weight increased inconsistently as plant density increased. The 30 × 30-cm spacing was not dense enough. Branching decreased and the position of the first marketable fruit attachment moved up as plant density increased. Delaying destructive harvest until many over-mature fruit were present often did not increase marketable fruit yield and always reduced the proportion of total harvested fruit weight due to marketable fruit. Overall, percentages of marketable yield obtained by destructive harvests of HD plants were low compared to the cumulative marketable yield from control plants. However, the labor-saving potential was high. A prototype machine for harvest of HD okra has been developed, and further testing is planned.

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.

scholarly journals Naphthalene Acetic Acid and 2,3,5-triiodobenzoic Acid Affect the Response of Mature Orange Fruit to Abscission Chemicals

HortScience ◽  
2002 ◽  
Vol 37 (2) ◽  
pp. 348-352 ◽  
Author(s):  
Rongcai Yuan ◽  
Ulrich Hartmond ◽  
Walter J. Kender
Keyword(s):  
Acetic Acid ◽  
Abscission Zone ◽  
Naphthalene Acetic Acid ◽  
Mature Fruit ◽  
Fruit Abscission ◽  
Triiodobenzoic Acid ◽  
Valencia Orange ◽  
Auxin Concentration ◽  
Auxin Transport Inhibitor ◽  
Orange Fruit

Effects of NAA, TIBA, ethephon, and CMN-Pyrazole on fruit detachment force (FDF) of mature `Valencia' and `Hamlin' orange [Citrus sinensis (L.) Osb.] fruit were examined in 2000 and 2001. NAA effectively inhibited the reduction in FDF or fruit abscission caused by ethephon when applied to the abscission zone 24 hours before ethephon application, but had no significant effect when applied to the fruit without contacting the abscission zone, or to the peduncle ≈4 cm above the abscission zone. TIBA, an auxin transport inhibitor, decreased FDF of mature fruit and promoted fruit abscission when applied alone as a spray to the canopy or directly to the fruit peduncle. This response was dependent on TIBA concentration. TIBA was more effective when applied in combination with ethephon or CMN-Pyrazole than alone. These results are consistent with our previous data that endogenous auxin concentration in the abscission zone of mature `Valencia' orange fruit is one of the factors controlling the sensitivity and thus the responsiveness of the abscission zone of mature fruit to abscission chemicals. Chemical names used: 5-chloro-3-methyl-4-nitro-pyrazole (CMN-Pyrazole); 2-chloroethylphosphonic acid (ethephon); naphthalene acetic acid (NAA); 2,3,5-triiodobenzoic acid (TIBA).

Sign in / Sign up

Export Citation Format

Share Document