Effect of Blossom Density and Crop Load on Growth, Fruit Quality, and Return Bloom in ‘Honeycrisp’ Apple

From 2003 to 2006, the blossom level and crop load of ‘Honeycrisp’ apple (Malus × domestica Borkh.) trees on M.26 rootstocks were adjusted to improve fruit quality and return bloom. The treatments consisted of manually removing flower clusters to 50, 100, and 150 per tree, then at ≈50 d after full bloom, the crop load was adjusted to 3, 6, and 9 fruit/cm2 trunk cross-sectional area (TCSA), respectively. All flower and crop load adjustment significantly increased TCSA and canopy volume compared with the control. Classic biennial bearing was observed on the untreated control trees and those thinned to 150 blossom clusters per tree and 9 fruit/cm2 TCSA and was mitigated for trees with 50 and 100 blossom clusters followed by crop load adjustment to 3 and 6 fruit/cm2 TCSA, respectively. Fruit color the “on” year was always lower on the control trees; no difference was found in the “off” year. The treatments increased fruit weight proportional to crop load except for the 2004 “off” year. This study illustrates that for trees with ≈1 m3 canopy volume, the combined effects of blossom and crop load adjustment to 100 blossom clusters/tree followed by fruitlet adjustment to 6 fruit/cm2 TCSA and below will induce consistent annual production for ‘Honeycrisp’.

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Blossom and Fruitlet Thinners Affect Crop Load, Fruit Weight, Seed Number, and Return Bloom of `Northern Spy' Apple

HortScience ◽

10.21273/hortsci.39.6.1309 ◽

2004 ◽

Vol 39 (6) ◽

pp. 1309-1312

Author(s):

Douglas Nichols ◽

Charles Embree ◽

John Cline ◽

Hak-Yoon Ju

Keyword(s):

Mineral Oil ◽

Fruit Weight ◽

Hydroxybenzoic Acid ◽

Apple Cultivar ◽

Seed Number ◽

Full Bloom ◽

Cross Sectional ◽

Crop Load ◽

Year Effect ◽

Return Bloom

To determine the effect of blossom and fruitlet thinners on crop load, fruit weight, seed development during the year of treatment, and the subsequent year effect on return bloom, fruit weight and yield, a field trial using the biennial apple cultivar `Northern Spy' (Malus × domestica Borkh.) was established. Treatments applied at full bloom included ATS (ammonium thiosulphate) [12% (w/v) nitrogen, 26% (w/v) S]; TD [15.9% (w/v) diacarboxylic acid, 5.5% (w/v) dimethylalkylamine salt (Endothal)] and SCY [57% (w/v) pelargonic acid (Scythe)]. At 18 days after full bloom (DAFB), oil treatments [98% (w/v) mineral oil (Superior “70” oil)] were applied with S [480 g·L-1 a.i. carbaryl (Sevin XLR)] and without as a means of increasing the efficacy of S. BA [19 g·L-1 a.i. 6-benzyladenine/1.9 g·L-1 a.i. gibberellins 4+7 (Accel)]; S; and/or SA [100% (w/w) 2-hydroxybenzoic acid (salicylic acid)], were also applied in a factorial arrangement on the same day. Fruit abscission was significantly increased the year of treatment with BA, S, BA + S, BA + SA, S + SA, BA + S + SA, oil, and S + oil. Average fruit weight was enhanced by S, BA + S, BA + SA, S + SA, BA + S + SA, and S + oil although in the latter treatment the crop load was very low. Only treatments that included BA reduced the number of fully developed seeds per fruit and seed number per trunk cross-sectional area (TCA) and increased return bloom. Defining the number of fully developed seeds per tree coupled with crop load is proposed as a predictor of return bloom in `Northern Spy'.

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Bio-regulators improve fruit size and c olour and reduce crop-load and annual bearing of Honeycrisp™ apples

Canadian Journal of Plant Science ◽

10.4141/p04-059 ◽

2005 ◽

Vol 85 (2) ◽

pp. 453-455

Author(s):

C. G. Embree ◽

D. S. Nichols

Keyword(s):

Fruit Quality ◽

Malus Domestica ◽

Fruit Size ◽

Fruit Weight ◽

Fruit Colour ◽

Full Bloom ◽

Crop Load ◽

Fruit Thinning ◽

Colour Category ◽

Return Bloom

Honeycrisp™ [Malus × domestica (L.) Borkh.] can be a very profitable cultivar if fruit quality is high. Some crop-load bio-regulators were evaluated for improving fruit quality and annual flowering. Ammonium thiosulphate applied at full bloom reduced crop-load, increased fruit weight, fruit colour and return bloom. Fruitone N® combined with Sevin XLR® reduced the percent of fruit in the 40–60% colour category and also crop-load. Fruitone N® alone reduced crop-load. Key words: Honeycrisp™, fruit thinning, crop-load, return bloom

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Ethephon as a Blossom and Fruitlet Thinner Affects Crop Load, Fruit Weight, Fruit Quality, and Return Bloom of ‘Summerred’ Apple (Malus ×domestica) Borkh.

HortScience ◽

10.21273/hortsci.46.3.432 ◽

2011 ◽

Vol 46 (3) ◽

pp. 432-438 ◽

Cited By ~ 7

Author(s):

Mekjell Meland ◽

Clive Kaiser

Keyword(s):

Fruit Quality ◽

Malus Domestica ◽

Fruit Set ◽

Quality Parameters ◽

Fruit Weight ◽

Cross Sectional ◽

Biennial Bearing ◽

Green Background ◽

Soluble Solid ◽

Return Bloom

‘Summerred’ apples (Malus domestica Borkh.) are highly susceptible to biennial bearing if not properly thinned. This results in erratic yields and also affects fruit quality adversely. Between 2003 and 2005, ‘Summered’/‘M9’ trees were treated with ethephon at concentrations of 250, 375, and 500 mg·L−1 when most king flowers opened (≈20% bloom) or at concentrations of 500, 625, and 750 mg·L−1 when the average fruitlet size was 10 mm in diameter. The experiment was conducted with 2.5-m height slender spindle trees sprayed to the point of runoff with a hand applicator only when temperatures exceeded 15 °C. Within 2 weeks after the second application, fruit set was reduced linearly with increasing concentrations of ethephon to less than one fruitlet per cluster at the highest concentrations used. Most thinning treatments reduced fruit set significantly compared with unthinned trees. Fruit numbers per tree decreased significantly with increasing ethephon concentrations, and the highest concentrations of ethephon applied during bloom or when the average fruitlet size was 10 mm in diameter resulted in overthinning. Yield results confirmed the fruit set response in which yield reductions were significant at the highest concentrations of ethephon (2.1 kg/tree) compared with hand-thinned trees (7.3 kg/tree) in 2005. All thinning treatments resulted in higher percentage of fruits larger than 60 mm diameter compared with unthinned control fruit. Thinning resulted in significantly higher soluble solid contents, and this was especially so for hand-thinned trees. Other fruit quality parameters like yellow–green background color did not show a clear response to thinning. Return bloom was, however, improved on all thinned trees. It is recommended that ethephon be applied at a rate of 375 mg·L−1 when king flowers open or at a rate of 625 mg·L−1 when the average fruitlet size is 10 mm in diameter. This thins ‘Summerred’ apples to a target of approximately five fruits/cm2 per trunk cross-sectional area or 50 to 70 fruits per 100 flower clusters without impacting on fruit quality, yield, or return bloom the next year.

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EARLY SPRING APPLICATION OF AMINOETHOXYVINILGLYCINE (AVG) INCREASES FRUIT SET AND YIELD OF ‘ROCHA’ PEARS

Revista Brasileira de Fruticultura ◽

10.1590/0100-29452017982 ◽

2017 ◽

Vol 39 (4) ◽

Cited By ~ 3

Author(s):

MATEUS DA SILVEIRA PASA ◽

BRUNO CARRA ◽

CARINA PEREIRA DA SILVA ◽

MARLISE NARA CIOTTA ◽

ALBERTO FONTANELLA BRIGHENTI ◽

...

Keyword(s):

Fruit Quality ◽

Fruit Set ◽

Block Design ◽

Quality Attributes ◽

Fruit Weight ◽

Early Spring ◽

Full Bloom ◽

Growing Seasons ◽

Randomized Block Design ◽

Return Bloom

ABSTRACT The low fruit set is one of the main factors leading to poor yield of pear orchards in Brazil. Ethylene is associated with abscission of flowers and fruitlets. Then, the application of ethylene synthesis inhibitors, such as AVG, is a potential tool to increase fruit set of pears. The objective of this study was to evaluate the effect of AVG, sprayed at different rates and timings, on fruit set, yield and fruit quality of ‘Rocha’ pear. The study was performed in a commercial orchard located in the municipality of São Joaquim, SC, during the growing seasons of 2014/2015 and 2015/2016. Plant material consisted of ‘Rocha’ pear trees grafted on quince rootstock ‘BA29’. AVG was tested at different rates (60 mg L-1 and 80 mg L-1) and timings [full bloom, one week after full bloom (WAFB), and two WAFB), either alone or in combination. The experiment was arranged in a randomized block design, with at least five single-tree replications. The fruit set, number of fruit per tree, yield, estimated yield, fruit weight, return bloom, and fruit quality attributes were assessed. Fruit set and yield were consistently increased by single applications of AVG at 60 and 80 mg L-1 at both one and two weeks after full bloom, without negatively affecting fruit quality attributes and return bloom.

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Crop Load, Fruit Thinning and their Effects on Fruit Quality of Apple (Malus domestica Borkh.)

Acta Agraria Debreceniensis ◽

10.34101/actaagrar/24/3221 ◽

2006 ◽

pp. 29-35 ◽

Cited By ~ 2

Author(s):

József Racskó

Keyword(s):

Growth Rate ◽

Fruit Quality ◽

Fruit Size ◽

Flower Initiation ◽

Pome Fruit ◽

Cross Sectional ◽

Crop Load ◽

Fruit Thinning ◽

Return Bloom ◽

Tree Leaf

Crop load, a quantitative parameter used by industry, is generally defined as the number of fruit per tree. It is often expressed in terms of number of fruit per trunk cross-sectional area (fruit/TCSA). Crop load is the most important of all factors that influence fruit size, and the removing of a part of the crop is the most effective way to improve fruit size.The potential size of a given pome fruit is determined early in the season and growth proceeds at a relatively uniform rate thereafter. This uniform growth rate permits the accurate prediction of the harvest size of the fruit as early as mid-summer. The growth rate, once established, is not easily altered, and fruit numbers, therefore, can affect fruit size only within definite limits and maximum effectiveness requires adjustment in fruit numbers relatively early in the season. It was established, that „thinning does not change a potentially small fruit into a large fruit, but rather insures that a potentially large fruit will size properly.” Emphasis should be on estimating fruit numbers rather than fruit size.Fruit thinning can quickly reach the point of diminishing returns. Rather than a high percentage of large fruits, the objectives of thinning should be the elimination of the smallest fruits, improved fruit quality and annual production. Fruit thinning is accomplished by hand or chemical thinning. Chemical thinners are separated into categories as bloom thinners and post-bloom thinners. Early removal of potential fruit (blossom thinning) is currently used in many apple producing areas to enhance flower initiation for next year’s crop and thus, return bloom. It also results in reduced competition for photosynthates. Blossom thinners usually have a caustic effect on floral parts.The amount of fruit left on a tree should be determined by the vigor and general condition of the tree. Leaf area per fruit affects the number of spurs flowering the following season. It can be difficult to separate timing and fruit number effects in crop loading studies, as abscission rates after hand thinning of retained flowers/fruitlets tend to very with the time of hand thinning.

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Effects of Repeated Yearly Application of Chemical Thinners on `McIntosh' Apples

HortScience ◽

10.21273/hortsci.40.2.401 ◽

2005 ◽

Vol 40 (2) ◽

pp. 401-403 ◽

Cited By ~ 3

Author(s):

Duane W. Greene

Keyword(s):

Fruit Quality ◽

Fruit Weight ◽

Naphthaleneacetic Acid ◽

Crop Load ◽

Load Effects ◽

Return Bloom ◽

Repeated Use ◽

One Year ◽

And Control ◽

Storage Disorders

An experiment was initiated on mature `Morespur McIntosh'on M.7 rootstock to document the effects of repeated yearly applications of benzyladenine (BA) and naphthaleneacetic acid (NAA) on fruit quality at harvest, the development of storage disorders following regular air storage, and on return bloom. When analyzed over the 4-year period, thinning did not significantly reduce crop load. This result was due in large part to no thinning response one year and very poor set on all trees in another year. Thinners were effective at increasing return bloom over the course of the experiment. BA increased fruit weight but reduced red color compared with NAA treated and control trees. Fruit quality differences at harvests were attributed primarily to crop load effects. There were no fruit quality, return bloom, or storage disorders that could not be explained by treatment effects on crop load or due to previously known effects of individual thinners. The results of this experiment clearly suggest that there are no direct adverse effects following repeated use of either NAA or BA.

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Optimizing Crop Load for New Apple Cultivar: “WA38”

Agronomy ◽

10.3390/agronomy9020107 ◽

2019 ◽

Vol 9 (2) ◽

pp. 107 ◽

Cited By ~ 3

Author(s):

Brendon Anthony ◽

Sara Serra ◽

Stefano Musacchi

Keyword(s):

Fruit Quality ◽

Titratable Acidity ◽

Fruit Weight ◽

Solid Content ◽

Soluble Solid Content ◽

Apple Cultivar ◽

Flower Bud ◽

Cross Sectional ◽

Crop Load ◽

Washington State University

Crop load management is growing increasingly important as a factor related to biennial tendencies, post-harvest disorders, and inconsistent fruit quality in apples like “Honeycrisp”. Washington State University released a new apple cultivar, called “WA38”, in 2017. Limited literature is available about the productive characteristics of this new cultivar. An experimental trial evaluating the effect of crop load on leaf area, fruit quality, mineral composition, and return bloom of “WA 38” was conducted for two consecutive years (2017 and 2018) to determine an optimal crop load. Trees were trained as a spindle and grafted on Malling-9 Nic29 (Nic29) rootstocks. Crop loads were adjusted to 2, 4, 6, and 8 fruits/cm2 of trunk cross-sectional area (TCSA). Crop load had a significant effect on production, with yields ranging from 28 to 83 MT/ha in 2017. Fruit quality was impacted by increasing crop load, with a reduction in fruit weight, soluble solid content, firmness, dry matter, titratable acidity, and a delay in maturity. Leaf-to-fruit ratios were higher in lower crop loads. Relatively consistent flower bud formation was seen at the 6 and 8 fruits/cm2 categories. A possible threshold for optimal fruit quality and consistent bloom was identified around 6 fruits/cm2 TCSA.

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Crop Load Reduction and Fruit Size Following Multi-step Thinning of 'Empire' Apple

HortScience ◽

10.21273/hortsci.37.1.130 ◽

2002 ◽

Vol 37 (1) ◽

pp. 130-133 ◽

Cited By ~ 3

Author(s):

Ed Stover ◽

Mike Fargione ◽

Richard Risio ◽

Xiaoe Yang

Keyword(s):

New York ◽

Field Experiments ◽

Total Yield ◽

Fruit Size ◽

Fruit Weight ◽

Naphthalene Acetic Acid ◽

Cross Sectional ◽

Crop Load ◽

Contrast Analysis ◽

Return Bloom

Two years of field experiments were conducted in eastern New York to evaluate the efficacy of a multi-step thinning approach on reducing crop load (no. fruit per cm2 trunk cross-sectional area) and increasing fruit size of 'Empire' apple (Malus ×domestica Borkh.). Applications of Endothall (ET) at 80% bloom, NAA + carbaryl (CB) at petal fall (PF), and Accel™ + CB at 10 mm king fruitlet diameter (KFD), alone and in all combinations, were compared to a nonthinned control and to the application of NAA + CB at 10 mm KFD (commercial standard). In both 1996 and 1997, orthogonal contrasts indicated the multi-step treatment significantly increased fruit size, reduced cropload, and reduced yield compared to single applications. Effects on cropload of consecutive treatments were largely predicted by multiplying effects of individual treatments. Although all thinning treatments except for NAA + CB at PF in 1997 significantly reduced cropload, no single treatment thinned sufficiently to ensure good return bloom. Compared to NAA + CB at 10 mm KFD, multi-step thinning with NAA + CB at PF followed by Accel™ + CB at 10 mm KFD produced bigger fruits in both years, and resulted in a higher percentage of spurs carrying a single fruit in 1996. When fruit size was evaluated after removing the effect of cropload (cropload adjusted fruit weight), NAA + CB at PF, Accel™ + CB at 10 mm, and the two applied sequentially, resulted in greater cropload adjusted fruit weight than the nonthinned control in both years, whereas NAA + CB at 10 mm did not. Contrast analysis of treatments with and without ET showed no significant effect of including ET on fruit size, though total cropload was reduced at P = 0.10 and total yield was reduced (P = 0.03 in 1996 and P = 0.12 in 1997). No deleterious effects from multi-step treatments have been observed. All thinning treatments significantly increased return bloom in 1996 and 1997 compared to the control with little difference observed between treatments. Chemical names used: naphthalene acetic acid (NAA); 1-naphthyl-N-methylcarbamate [carbaryl (CB)]; 6-benzyladenine [BA (Accel™)]; 7-oxabicyclo (2,2,1) heptane-2,3 dicarboxylic acid [ET (Endothall™)]

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Thidiazuron Effects on Fruit Set, Fruit Quality, and Return Bloom of Apples

HortScience ◽

10.21273/hortsci.30.6.1238 ◽

1995 ◽

Vol 30 (6) ◽

pp. 1238-1240 ◽

Cited By ~ 14

Author(s):

Duane W. Greene

Keyword(s):

Fruit Set ◽

Fruit Weight ◽

Soluble Solids ◽

Refrigerated Storage ◽

Full Bloom ◽

Crop Load ◽

Flesh Firmness ◽

Solids Concentration ◽

Return Bloom ◽

Soluble Solids Concentration

Thidiazuron (THI) applied at full bloom (FB) at 10 or 50 mg·liter–1 thinned `McIntosh' apples (Malus domestica Borkh.) and reduced return bloom. The same concentrations applied at 22 days after FB (DAFB) thinned excessively and inhibited return bloom even more. THI at 1, 5, or 15 mg·liter–1 did not thin `Empire' at FB, but when applied 18 DAFB, these concentrations achieved thinning, with 5 mg·liter–1 reducing crop load to near ideal commercial levels. Return bloom of `Empire' was not influenced by THI at these concentrations. THI increased fruit weight, flesh firmness, soluble solids concentration, and fruit asymmetry on `McIntosh' and `Empire' and reduced red pigmentation and seed count on `McIntosh', especially when applied 22 DAFB. A FB application of CPPU and THI, each at 5 or 10 mg·liter–1, on `Delicious' increased the fruit length: diameter (L: D) ratio and flesh firmness (at harvest and following 26 weeks of refrigerated storage and reduced return bloom). CPPU at either 5 or 10 mg·liter–1 increased the fruit L: D ratio more than 25 mg Promalin/liter. Chemical names used: N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron); N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU); N-(phenylmethyl)-1H-purine-6-amine plus gibberellins A4+7 (Promalin).

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Multiple season-long sprays of ethephon or NAA combined with calcium chloride on ‘Honeycrisp’ apples: I. Effect on bloom and fruit quality attributes

Canadian Journal of Plant Science ◽

10.1139/cjps-2018-0196 ◽

2019 ◽

Vol 99 (4) ◽

pp. 444-459

Author(s):

John A. Cline

Keyword(s):

Calcium Chloride ◽

Fruit Quality ◽

Quality Attributes ◽

Naphthaleneacetic Acid ◽

Fruit Firmness ◽

Biennial Bearing ◽

Fruit Drop ◽

Fruit Maturity ◽

Return Bloom ◽

Honeycrisp Apples

‘Honeycrisp’ apple trees are highly prone to biennial bearing and predisposed to bitter pit. The hypothesis that tank mix sprays of ethephon (ETH), naphthaleneacetic acid (NAA), and 1-aminocyclopropane carboxylic acid (ACC) combined with calcium chloride (CaCl2) can mitigate these production problems was tested in a 3-yr study. Mature ‘Honeycrisp’ trees were treated with either three or six summer applications of 150 mg L−1 ETH or 5 mg L−1 NAA, all tank-mixed with and without CaCl2, or two or five applications of 150 mg L−1 ACC (without CaCl2). Treatments were applied at 10-d intervals and initiated between 21 and 26 June. All treatments had little effect on enhancing return bloom of ‘Honeycrisp’. NAA, ETH, and CaCl2 all influenced fruit maturity and quality at harvest to varying degrees and across years. Fruit treated with NAA were firmer compared with untreated fruit in 2 out of 3 yr, whereas overall, fruit treated with six sprays of ETH had lower fruit firmness and were more mature. NAA had less influence on fruit quality attributes at harvest than did ETH, and decreased pre-harvest fruit drop (PFD). PFD increased with ETH in 1 out of 2 yr, whereas ACC and NAA both decreased PFD in 1 out of 2 yr. Overall, ETH and NAA, with or without CaCl2, had significant but inconsistent effects on fruit quality and maturity, all dependent on the year and number of applications. Adding CaCl2 decreased fruit firmness in 2 out of 3 yr.

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