Chemical Loosening Agents to Assist Mechanical Harvest of Olive1

Abstract

(2-chloroethyl)phosphonic acid (ethephon) applied at pH 6.8 to 7.0 resulted in fruit loosening which allowed mechanical harvest of at least 85% of the olive crop but there was excessive leaf loss. Inclusion of calcium salts helps offset leaf loss, but also decreases fruit loosening. 2-chloroethyl-tris-(2-methoxyethoxy)-silane (Alsol) and (2-chloroethyl)-methyl-bis-(phenylmethoxy)-silane (CGA 15281) appeared to be more superior looseners than either ethephon or GAF 7767141 (an ethylene generating material) with less leaf loss following treatment.

Ethylene-releasing Compounds and the Laboratory Modeling of Olive Fruit Abscission vs. Ethylene Release

“…Using excised shoots, the reduction in FRF of fruit treated with a 69 mM ET droplet was compared to that of fruit in which the whole shoot was sprayed to runoff with 13.8 mM ET, a concentration effective in field spray trials (26). Both showed a reduction in FRF by 31 hr (19).…”

“…A review of ERC field trials (4,19,26) and laboratory work (22,23,31) suggests that increasing initial ethylene release from ERC's may reduce total leaf abscission while maintaining satisfactory fruit abscission. This increase has been accomplished by modifying solution pH (17,26), which controls the rate of the ERC hydrolysis reaction (6,10). As demonstrated here, the fruit AZ can respond rapidly to a large initial exposure to ethylene.…”

“…Indeed, after 30 years of field experiments for selection of abscission-inducing chemicals to aid in mechanization of olive fruit harvest, compounds which release ethylene have proven to be most promising. Even so, widespread use of ethylenereleasing compounds (ERC's) has not occurred because of the inconsistency of treatments in loosening fruit suitably without promoting excessive leaf loss (16,26). This lack of treatment consistency is matched by a lack of understanding of ethylene release from ERC's and its relation to the abscission process in olive fruit and leaves.…”

Calcium and Ethephon Effects on Tabasco Pepper Leaf and Fruit Retention and Fruit Color Development

“…Chemical name used: (2-choloroethyI)phosphonic acid (ethephon).The action of ethephon on peppers (Capsicum annuum L. and C. frutescens L.) is affected by pepper type (1, 13), cultivar (2), crop maturity (2, 10, 14), number of applications (2), rate of application (1-5, 8), and air temperature (5,14). The use of ethephon as a pepper fruit ripening agent, however, is limited by premature fruit abscission and defoliation (1,2,5,8,14).Ethylene-induced abscission can be reduced by treatment with calcium (6,7,11,12). Calcium not only increases ethephon solution pH (6, 7), but also maintains the integrity of cell walls and membranes in the abscission layer (11,12).…”

“…Ethylene-induced abscission can be reduced by treatment with calcium (6,7,11,12). Calcium not only increases ethephon solution pH (6, 7), but also maintains the integrity of cell walls and membranes in the abscission layer (11,12).…”