GIBBERELLIC ACID IS A POTENTIAL SWEET CHERRY CROP LOAD MANAGEMENT TOOL

The development of novel crop load management techniques will be critical to the adoption and success of high density sweet cherry orchard systems based on new clonal rootstocks. Herein we report on a comparison of potential means of balancing crop load of `Bing' sweet cherry grown on the productive and precocious rootstocks `Gisela 5' and `Gisela 6'. In 2002, thinning treatments were applied to entire trees and consisted of an unthinned control (C), and manual removal of 50% of the blossoms (B) or 50% of 2-year-old and older fruiting spurs (S), throughout the tree. In 2003 all trees were left unthinned to characterize the carry-over effect of thinning treatment in 2002. In 2002, compared to C, thinned trees had 38% to 49% fewer fruit per tree, 22% to 42% lower yield, 8% to 26% higher fruit weight, and 2% to 10% larger fruit diameter. S and B treatments reduced yield by 42% and 22% on `Gisela 5' and by 40% and 31% on `Gisela 6', respectively. `Gisela 5'-rooted trees showed greater improvements in fruit quality than did trees on `Gisela 6'. Compared to C-, S-, and B-treated trees on `Gisela 5' yielded fruit that was 15% and 26% heavier, respectively. Yield of fruit ≥25.5 mm diameter was increased by 240% by S and 880% by B, though yield of this size fruit was still low (1.5 and 5.2 kg/tree, respectively). Neither technique had any beneficial carryover effect in the year following treatment despite S trees bearing about 25% fewer fruit than B and C trees. In both years, `Gisela 5'-rooted trees bore about 15% fewer fruit than trees on `Gisela 6'. Compared to `Gisela 5', `Gisela 6'-rooted trees were about 41%, 46%, and 24% more productive for C, S, and B, respectively. Number of fruit/tree in 2003 was within 4% and 8% of the previous year on `Gisela 6' and `Gisela 5', respectively. Crop value analyses suggest growers would be rewarded for producing high yields of medium size fruit (e.g., 21.5 to 25.4 mm) compared to low yields of high quality fruit.

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Influence of Aminoethoxyvinylglycine on Pecan Fruit Retention

HortScience ◽

10.21273/hortsci.44.7.1884 ◽

2009 ◽

Vol 44 (7) ◽

pp. 1884-1889

Author(s):

Bruce W. Wood ◽

Leonardo Lombardini ◽

Richard J. Heerema

Keyword(s):

Crop Yield ◽

Field Studies ◽

Carya Illinoinensis ◽

Management Tool ◽

Load Management ◽

Crop Load ◽

Ethylene Inhibitor ◽

The U.S ◽

June Drop ◽

Increase Crop Yield

Insufficient fruit retention limits profitability of certain pecan [Carya illinoinensis (Wangenh.) K. Koch] cultivars. The present study examined efficacy of aminoethoxyvinylglycine (formulated as ReTain®; Valent BioSciences, Libertyville, IL), a natural ethylene inhibitor, for increasing crop-load through increased fruit retention in pecan trees grown at three distinct locations within the U.S. pecan belt. Several years of field studies found that timely postpollination ReTain® sprays [132 mg·L−1 a.i. (11.7 oz./acre)] to canopies could increase fruit retention of ‘Desirable’ and increase crop yield by 16% to 38% in trees carrying a “moderate to heavy” crop. ReTain® did not detectably increase fruit retention on trees carrying a “light” crop-load. The ReTain®-associated increase in yield of “heavy” crop-load trees did not necessarily decrease subsequent year yield. ReTain® appears to offer commercial potential as a crop-load management tool for ‘Desirable’ through regulation of Stage II drop (i.e., June-drop), but may not be efficacious for all cultivars.

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Crop Load Management Does Not Consistently Improve Crop Value of ‘Sweetheart’/‘Mazzard’ Sweet Cherry Trees

HortTechnology ◽

10.21273/horttech.21.5.546 ◽

2011 ◽

Vol 21 (5) ◽

pp. 546-553 ◽

Cited By ~ 5

Author(s):

Todd C. Einhorn ◽

Debra Laraway ◽

Janet Turner

Keyword(s):

Fruit Quality ◽

Sweet Cherry ◽

Load Level ◽

Fruit Growth ◽

Soluble Solids ◽

Load Management ◽

Fresh Market ◽

Crop Load ◽

Tree Crop ◽

Return Bloom

The effect of crop load level on vegetative growth, fruit growth, yield, fruit quality, surface pitting, crop value and return bloom was studied over a 2-year period on 9- and 10-year-old ‘Sweetheart’/‘Mazzard’ sweet cherry (Prunus avium) trees. In early spring, whole-tree crop loads were adjusted to two different levels by removal of reproductive buds (either 50% or all but one) from spurs and compared with an unthinned control. In 2009, heavy crop loads of unthinned trees reduced fruit size by 30 days after full bloom (DAFB). At harvest, fruit diameter of thinned treatments was increased 22% and 27% compared with unthinned fruit. Fruit quality attributes [soluble solids concentration (SS), fruit firmness, and total acids (TA)] were significantly greater for thinned treatments. Thinned treatment yields were reduced 40% to 54% relative to unthinned trees, with greater percentages of fruit in large size classes. Despite significantly fewer fruit per tree, moderately thinned trees had a higher estimated crop value ($142 per tree) than unthinned trees ($125 per tree). Crop value was lowest for the heavily thinned treatment ($107 per tree), reflecting overthinning. In 2010, shoot growth was negatively related to crop load level. Fruit growth of unthinned trees was not significantly affected by higher fruit density until 89 DAFB. Yield of 2010 unthinned trees was 87% of 2009, while thinned tree yields were similar between years. Improved fruit quality and greater percentages of large fruit were observed for thinned treatments in 2010; however, crop value was highest for unthinned trees ($190 per tree), even though 18% of the fruit were too small for fresh market sale. Surface pitting was unaffected by crop load level in either year. Return bloom (flowers per reproductive bud and reproductive buds per spur) was significantly, negatively related to the prior season's crop load in 2010 and 2011. In the current sweet cherry pricing structure, higher crop value is associated with large volumes of medium-sized fruit. Thinning to manage crop load of low-medium density, productive ‘Sweetheart’/‘Mazzard’ trees will not be an annual requirement, though in heavy fruit set years crop load management will improve crop value.

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Regulating crop load of ‘Sweetheart’ and ‘Van’ sweet cherry for optimal quality and reduced risk of cracking

Acta Horticulturae ◽

10.17660/actahortic.2017.1161.16 ◽

2017 ◽

pp. 91-96

Author(s):

S.A. Bound ◽

D.C. Close ◽

P.F. Measham ◽

M.D. Whiting

Keyword(s):

Sweet Cherry ◽

Crop Load ◽

Optimal Quality ◽

Reduced Risk

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THE EFFECT OF IRRIGATION, GIBBERELLIC ACID AND NITROGEN ON THE OCCURRENCE OF DOUBLE FRUIT IN 'VAN' SWEET CHERRY

Acta Horticulturae ◽

10.17660/actahortic.2008.795.100 ◽

2008 ◽

pp. 645-650 ◽

Cited By ~ 2

Author(s):

H. Engin ◽

A. Ünal

Keyword(s):

Gibberellic Acid ◽

Sweet Cherry

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Effects of the bioregulators ACC, 6-BA, ABA, and NAA as thinning agents on Gala apples

Canadian Journal of Plant Science ◽

10.1139/cjps-2019-0014 ◽

2020 ◽

Vol 100 (2) ◽

pp. 185-201 ◽

Cited By ~ 2

Author(s):

Michelle H. Cortens ◽

John A. Cline

Keyword(s):

Abscisic Acid ◽

Fruit Quality ◽

Fruit Set ◽

Load Management ◽

Environmental Concerns ◽

Naphthaleneacetic Acid ◽

Management Options ◽

Crop Load ◽

Southern Ontario ◽

Malus Domestica Borkh

Gala apple (Malus domestica Borkh.) trees are prone to heavy cropping but respond to chemical fruitlet thinners to reduce crop load and improve fruit quality. Environmental concerns over the fate of the chemical fruitlet thinner carbaryl is widely acknowledged, but crop load management options are limited. In southern Ontario, Gala trees were treated with new thinning compounds or combinations to determine post-bloom thinning efficacy and resulting fruit quality. Treatments included 6-benzyladenine (6-BA) combined with naphthaleneacetic acid (NAA) or abscisic acid (ABA), and 1-aminocyclopropane-1-carboxylic acid (ACC) alone applied at 9 mm in 2014 and 17 mm in 2015. The treatment NAA + 6-BA produced unacceptably small “pygmy” fruit when applied at 17 mm fruitlet diameter. ABA at 150 and 300 mg L−1 and ACC at 150 mg L−1, when applied at 17 mm fruitlet diameter, resulted in acceptable fruit set, crop load, and quality results in comparison with the carbaryl thinner in 1 yr. The bioregulators ACC and ABA combined with 6-BA showed commercial potential for thinning Gala fruit but require further evaluation.

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EFFECT OF IRRIGATION AND CROP LOAD MANAGEMENT ON FRUIT NUTRITION AND QUALITY FOR AMBROSIA/M.9 APPLE

Acta Horticulturae ◽

10.17660/actahortic.2010.868.4 ◽

2010 ◽

pp. 63-72 ◽

Cited By ~ 6

Author(s):

D. Neilsen ◽

G.H. Neilsen ◽

L. Herbert ◽

S. Guak

Keyword(s):

Load Management ◽

Crop Load

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Optimizing Fruit-Thinning Strategies in Peach (Prunus persica) Production

Horticulturae ◽

10.3390/horticulturae6030041 ◽

2020 ◽

Vol 6 (3) ◽

pp. 41 ◽

Cited By ~ 1

Author(s):

Mary Sutton ◽

John Doyle ◽

Dario Chavez ◽

Anish Malladi

Keyword(s):

Fruit Development ◽

Fruit Size ◽

Fruit Weight ◽

Load Management ◽

Growth Responses ◽

Crop Load ◽

Fruit Number ◽

Fruit Thinning ◽

Adverse Weather ◽

One Year

Fruit size is a highly valued commercial trait in peach. Competition among fruit and among other sinks on a tree reduces potential growth rate of the fruit. Hence, crop-load management strategies such as thinning (removal of flowers or fruit) are often practiced by growers to optimize fruit size. Thinning can be performed at bloom or during early fruit development and at different intensities to optimize fruit growth responses. Responses to thinning may be cultivar and location specific. The objective of the current study was to fine-tune thinning strategies in the southeastern United States, a major peach producing region. Timing and intensity of thinning were evaluated across multiple cultivars over three years. Thinning at bloom or at 21 d after full bloom (DAFB) improved fruit size in comparison to unthinned trees in ‘Cary Mac’ and ‘July Prince’, respectively, in one year. Bloom-thinning reduced fruit yield (kg per tree) in the above cultivars in one year, suggesting that flower thinning alone may not be a viable option in this region. Intensity of thinning, evaluated as spacings of 15 cm and 20 cm between fruit, did not differentially affect fruit weight or yield. However, fruit diameter decreased quadratically with increasing fruit number per tree in ‘Cary Mac’, ‘July Prince’ and ‘Summer Flame’. Similarly, fruit weight decreased quadratically in response to increase in fruit number per tree in ‘Cary Mac’ and ‘July Prince’. Further, yield-per-tree decreased with increasing fruit size in ‘Cary Mac’ and ‘July Prince’. Importantly, these relationships were cultivar specific. Together, the data suggest that achieving a target fruit number per tree is an effective strategy for crop-load management to optimize fruit size in southeastern peach production. The target fruit number per tree may potentially be achieved through a combination of flower and fruit-thinning during early fruit development. Such an approach may provide flexibility in crop-load management in relation to adverse weather events.

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