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Open access

Robert C. de Wilde

Abstract

In 1946 Kabachnik and Rossiiskaya (96) reported the chemical synthesis of “2-chloroethanephosphonic” acid and in 1963 Maynard and Swan (125) described the formation of ethylene from this compound. When (2-chloroethyl)phosphonic acid (ethephon; also variously cited as 2-chloroethanephosphonic acid, Amchem 66-329, CEPA and Ethrel® disintegrates, it releases ethylene and also chloride and phosphate ions (43, 67, 125, 196, 202) Ethephon is essentially stable in aqueous solutions below pH 4. When the presence of hydroxyl ions is increased and the pH rises above 4, disintegration of the chemical takes place. The pH of the cytoplasm of plant cells is generally greater than 4, so the plant growth activity of ethephon has been attributed primarily to its ability to release ethylene to plant tissues (14, 43, 132, 195, 196). Ethrel formulations provide a convenient way to apply ethylene without the need of gas-confining chambers.

Open access

Roger H. Young and Otto L. Jahn

Abstract

14C-Ethylene was the major breakdown product of 1,214C-(2-chloroethyl)phosphonic acid (ethephon)-treated fruit and leaves of several Citrus taxons. Neither 14CO2 nor other by-products were detected. Most of the nonethylene radioactivity recovered was from tissue surfaces. Radioactivity was not readily translocated from leaves or fruit.

Open access

W. A. Dozier Jr. and J. A. Barden

Abstract

Concentrations up to 4000 ppm of (2-chloroethyl)phosphonic acid (ethephon) did not affect the net photosynthesis (Pn) of leaves on greenhouse grown apple trees. Leaf respiration was increased by 4000 ppm ethephon, but not by lower concn. Pn rates did not differ between cvs., but respiration of ‘Golden Delicious’ leaves was greater than that of ‘York’ leaves.

Open access

George C. Martin, Larry B. Fitch, G. Steven Sibbett, Gregory L. Carnill, and David E. Ramos

Abstract

Foliar sprays of (2-chloroethyl)phosphonic acid (ethephon) were applied at 50, 100, and 150 ppm to French prune trees at 50% petal fall and when seed length was 8.3 to 9.4 mm. All concentrations thinned fruits within 3 to 4 weeks after treatment. The treatments increased soluble solids and fruit size, and in some instances decreased dry tonnage. Return bloom the following year was greater on treated trees than on controls. Also, fall coloration patterns appeared earlier on the treated trees. No phytotoxic effects from the treatments were evident on the fruits.

Open access

Walter E. Splittstoesser and Joseph S. Vandemark

Abstract

In a 2-year field study, direct-seeded and transplanted tomato cvs. (Heinz 1350, Heinz 1439, Manalucie, Roma) were treated with (2-chloroethyl)phosphonic acid (ethephon) when 10% of the fruit was pink. Ethephon promoted ripening when it was applied to the leaves only, to the fruit only or to the entire plant. Ethephon induced yellowing of the leaves, accelerated ripening 10 days, and concentrated the bulk of the total yield into this harvest. Ethephon induced smaller immature fruit to mature and ripen and thus reduced the average individual fruit weight of harvestable fruit from the large fruited ‘Manalucie’ but not other cultivars.

Open access

W. A. Dozier Jr. and J. A. Barden

Abstract

Sprays of (2-chloroethyl)phosphonic acid (ethephon) were applied to young apple trees in 2 greenhouse experiments. Ethephon suppressed terminal growth, internode length, and elongation of the pre-treatment stem. Ethephon applied at 4,000 ppm, 64 days after bud break resulted in abscission of some shoot apices. Lateral branching was induced by ethephon, but it was not dependent on abscission of the shoot apex. Whereas dry weight of the lateral branches was increased at 4,000 ppm, total stem dry weight was decreased by ethephon.

Open access

L. J. Edgerton and A. H. Hatch

Abstract

Radioactive (2-chloroethyl)phosphonic acid (ethephon) was applied to leaf and fruit surfaces 6 to 10 days before normal harvest date. Samples were collected periodically following application and analyzed with appropriate extraction and counting procedures. The level of radioactive ethephon increased in the fruit for about 48 to 72 hr, then decreased to a low level after 6 days. No intermediate metabolites were detected in the fruits. It was found that the majority of the ethephon in the fruits moved there from the application on adjacent leaves; relatively small amounts moved directly into the fruit from surface application. Radioactive ethylene was detected within 12 hr after application of the 14C-ethephon on the leaf surfaces.

Open access

E. T. Sims Jr., C. E. Gambrell Jr., and G. E. Stembridge

Abstract

Ethephon ((2-chloroethyl)phosphonic acid) at 50 to 200 ppm hastened the maturation of peach fruit of the cvs. ‘Cardinal’, ‘Ranger’, ‘Redhaven’, ‘Blake’, and ‘Richhaven’ over a range of application times. Stimulation of maturation was not attributed solely to reduced fruit load, since an influence on maturation was found even when ethephon-treated trees bore no fewer fruits than hand-thinned controls. When treated and nontreated ‘Richhaven’ fruit were harvested at a comparable maturity based on firmness, ground and flesh color a and a/b values were increased by ethephon, as were soluble solids. No differences were found in b values for ground or flesh color or in total titratable acidity. Fruit treated with ethephon exhibited more uniformity in firmness and color than untreated fruit at shipping maturity, a characteristic which has potential value in facilitating once-over mechanical harvesting operations.

Open access

H. C. Dostal and G. E. Wilcox

Abstract

Total yield and percentage of ripe tomato fruit were significantly increased following single foliar applications of 0.84 lb. per acre (2-chloroethyl)phosphonic acid (ethephon). Maximum responses were noted at 14 days after treatment. Three tomato cultivars seeded on 3 dates responded similarly. Seventeen days after ethephon application at the 15 percent ripe fruit stage, useable ripe fruit yield was increased to more than 90 percent of the total fruit yield, compared to 59 percent useable ripe fruit for the control. The application of ethephon advanced harvest by 12 to 14 days, with an increase in useable ripe fruit yield of 5 to 10 tons per acre over the optimum potential of the normal ripening rate for single-harvest culture.

Open access

W. A. Dozier Jr. and J. A. Barden

Abstract

Ethephon, (2-çhloroethyl)phosphonic acid, was applied at rates of 125 ppm and higher to young apple trees in 3 greenhouse experiments. Leaf expansion and total number of leaves were reduced by ethephon; the effective concentration became lower as the growing season progressed. Leaf area on the primary shoot was reduced by 1,000 and 4,000 ppm ethephon, but was increased on the lateral branches by 4,000 ppm. Total leaf area was suppressed only by the 1,000 ppm treatment. Leaf necrosis occurred at 625 ppm and higher concentrations in 1 experiment. Lateral bud scales abscised and a proliferation of cells under the leaf scar occurred on trees treated with 7,500 and 10,000 ppm ethephon. Many lateral buds abscised on the lower two-thirds of trees treated with 10,000 ppm. Leaf abscission was induced by ethephon, and the higher concentrations caused earlier and more rapid leaf drop. The oldest leaves abscised first, and most leaves became somewhat chlorotic prior to abscission. Leaves apparently had to be of a certain physiological age before they could be induced to abscise.