The application of methyl jasmonate (MeJA) to grapes (Vitis vinifera L.) may decrease fruit detachment force (FDF) and promote the development of dry stem scars on the berries, both of which could improve the quality of machine-harvested raisin grapes. However, treatment with MeJA also promotes preharvest fruit drop, which is undesirable. Thus, experiments were conducted to determine how the concentration of MeJA applied and time after treatment affect FDF and abscission of grapes. Mature ‘Thompson Seedless’ grapevines were treated with one of five different solutions containing 0, 0.2, 2, 10, or 20 mm MeJA, and FDF and fruit abscission were monitored for ≈2 weeks. Treatment with 2 mm or less MeJA had inconsistent effects on FDF and did not promote abscission, whereas treatment with 10 to 20 mm MeJA reduced FDF within 2 to 3 days after treatment (DAT) and promoted abscission, which began on ≈3 DAT and persisted for ≈8 DAT. Thus, to optimize the use of MeJA as a harvest aid for ‘Thompson Seedless’ may require application of between 2 and 10 mm MeJA followed by harvest within 3 DAT.
Raquel González-Herranz, Kimberley A. Cathline, Matthew W. Fidelibus, and Jacqueline K. Burns
A. Pendergrass, F. M. Isenberg, L. E. St. John Jr., and Donald J. Lisk
Onion foliage sprayed before harvest with a neo-decanoic acid mixture (Wiltz-65) became bleached and limp. The rate of water loss from bulb necks was accelerated. Residue analysis shows that at concentrations sufficient to wilt tops, about 1 ppm is recoverable from bulbs before storage, none after 4 months’ storage. Neck rot was increased in 2 cultivars which form double bulbs but not in one where bulbs grow singly.
S. C. Phatak, M. E. Austin, and J. S. Mason
(2-Chloroethyl)phosphonic acid (ethephon) was applied at 0, 570, 1000 and 2000 ppm to muscadine grapes (Vitis rotundifolia Mich. cv. Hunt), 1, 2, or 3 days before once-over harvest. All ethephon treatments increased berry abscission and reduced skin tear due to harvest when berries were harvested 2 days or 3 days after spraying. Delaying harvest to 3 days after treatment with 2000 ppm ethephon increased berry abscission to 46% and reduced skin tear to 9% in 1977. In 1978, 2000 ppm of ethephon increased berry abscission to 29% and reduced skin rupture to 29%. Taste panels could not detect flavor difference from the ethephon treatments.
Larry A. Stein, George Ray McEachern, and J. Benton Storey
Ethephon was trunk injected into the transpiration stream of pecan trees 10 to 21 days before shuck split in an attempt to expedite shuck opening in 1983. Ethephon concentrations were based on the estimated amount of water flowing through the tree per day. At College Station and Hondo, Texas, a 10 ppm injection significantly increased shuck opening. Leaf drop was only 35% at 10 ppm compared to much higher leaf drop in previous research. There was no difference in number of nuts set and the extent of limb dieback between the control trees and those trunk injected with 10 ppm ethephon. At Ft. Stockton and Midkiff, Texas, injections of 10, 20, and 40 ppm increased nut opening and early leaf drop, but reduced fruit set in the following year (1984). There was no limb dieback at these locations. Injections of trees in El Paso failed to cause shuck opening.
G. S. Howell Jr., B. G. Stergios, S. S. Stackhouse, H. C. Bittenbender, and C. L. Burton
Application of (2-chloroethyl)phosphonic acid (ethephon) reduced fruit removal force (FRF) as much as 50% depending on concentration and time of application. Reduction in FRF allowed reduced mechanical harvesting vibration frequency which reduced damage to berries during harvest and thus increased shelf-life. Mechanical harvest was further facilitated by ethephon-induced color development and hastening of abscission which reduced the number of machine harvests required.
Martinez T. Miguel and Duarte U. Miguel
Ethephon and NAA in 2 combinations were applied to 17 year old “Western” pecan trees near the coast of Hermosillo, in Sonora, Mexico. The treatments were: a) 300 ppm NAA plus 800 ppm Ethephon; b) 300 ppm NAA plus 500 ppm Ethephon. These treatments were applied at three different times: first, when nut physiological maturity was reached, second, 10 days after nut physiological maturity and third, 21 days after physiological maturity was reached. The best treatment was the combination of 300 ppm NAA plus 800 ppm Ethephon applied 10 days after physiological maturity. This treatment resulted in 100% shuck dehiscence, 10% leaf abscission, 2 weeks advance in harvest and the best kernel color when compared to control.
Anish Malladi, Tripti Vashisth, and Lisa Klima Johnson
, 2004 ). In blueberry, ethephon has been evaluated previously in relation to its effects on concentrating fruit ripening and also as a potential mechanical harvest aid ( Ban et al., 2007 ; Dekazos, 1976 , 1978 ; Eck, 1970 ; Howell et al., 1976
Ray E. Worley
Dikegulac, when applied in the fall of a dry year, did not enhance shuck dehiscence of pecan (Carya illinoensis (Wang.) K. Koch but did promote increased numbers of new shoots on young trees the next spring.
Alexander D. Pavlista, Gary Hergert, Dipak K. Santra, and James A. Schild
The lowest pods on common bean (Phaseolus vulgaris) are on or near the ground. Yields may improve by raising these pods to reduce yield loss, especially with direct harvest. The objective of this field study was to use gibberellic acid (GA3) to raise lower pods and increase yield. Seeds of cultivars Poncho (Type III, pinto) and Matterhorn (Type II, great northern) were dipped in GA3 at 0, 125, 500, and 2000 ppm and planted in 30-inch rows (2005). Stem elongation was promoted, but emergence and yield were decreased especially for ‘Poncho’. In foliar tests in 30-inch rows (2005 and 2006), GA3 was applied to newly expanded unifoliolate leaves. Doses were 0, 0.5, 2, and 8 ppm for ‘Poncho’ and 0, 31.25, 125, and 500 ppm for ‘Matterhorn’. The higher doses raised the low pod by 2 inches, and yields harvested conventionally were increased from 14% to 18%. In 2007, ‘Poncho’ and ‘Matterhorn’ unifoliolate leaves were treated with GA3 at 0, 2, and 4 ppm, and 0, 62.5, and 125 ppm, respectively, and then portions of each plot were harvested either manually, conventionally, or directly. Planting was in 22- and 30-inch row spacing. Lower pods were raised by ≈1 inch by GA3. Yields from conventional and direct harvest were increased by foliar GA3 application for both cultivars and both row spacings. Yield from directly harvested GA3-treated plots was comparable to that from untreated conventionally harvested plots. GA3 may play a role in increasing yield from directly harvested common bean in conjunction with genetic and mechanical improvements.
Fumiomi Takeda and Donald L. Peterson
Separation pull force of thornless blackberries (Rubus spp.) decreased at a rate insufficient to allow adequate mechanical harvest differentiation between the black ripe and red fruit. When a force sufficient to remove 80% of black ripe fruit was applied to floricanes, green and red fruit comprised as much as 50% of detached fruit. Ethephon, applied at 500 and 1000 ppm 4 days prior to harvest, reduced fruit size and total soluble solids, but increased the ripe/unripe harvest ratio more than two-fold. Two shaker models tested were effective in removing black ripe fruit. Of the two, the unit with higher frequency (40 vs. 25 Hz), but with shorter stroke (1.7 vs. 5.0 cm), was more efficient, as it removed fewer unripe fruit. Chemical name used: (2-chloroethyl) phosphonic acid (ethephon).