Improving fruit size and packout of Late Valencia oranges with ethephon fruit-thinning sprays

1992 ◽  
Vol 32 (6) ◽  
pp. 753 ◽  
Author(s):  
RJ Hutton
Keyword(s):  
Fruit Quality ◽  
Fruit Size ◽  
High Volume ◽  
Cropping Pattern ◽  
Alternate Bearing ◽  
Fruit Thinning ◽  
Unaffected Control ◽  
Marketable Fruit ◽  
Orange Trees ◽  
Spray Treatment

This study set out to establish concentrations of ethephon sprays that could reliably thin alternate cropping orange trees in a heavy set year to improve fruit quality for fresh marketing. An optimum concentration of ethephon as a thinning agent was identified for the practical control of alternate cropping in Late Valencia oranges. A single, high volume spray of ethephon (as Ethrel, 42-60 mL/100 L water), applied in a heavy-set year at 6-8 weeks post bloom when fruitlet size was 10-15 mm diameter, induced a 15-20% reduction in fruit number. This resulted in significantly improved fruit size and marketable outturn with negligible yield penalty. In the 2 successive harvests following spray treatment, the cropping pattern remained uniform and a 14% improvement in packout (marketable fruit size <100 counts per carton) was maintained. Internal fruit quality was unaffected. Control of alternate bearing was carried forward for at least 2 seasons with relatively stable yields following a single spray treatment.

scholarly journals Temperature Has a Greater Effect on Fruit Growth than Defoliation or Fruit Thinning in Strawberries in the Subtropics

Agriculture ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 127
Author(s):  
Christopher M. Menzel
Keyword(s):  
Opposite Effect ◽  
Fruit Size ◽  
Fruit Weight ◽  
Fruit Growth ◽  
Effect Of Temperature ◽  
Fragaria Ananassa ◽  
Fruit Thinning ◽  
Mature Leaves ◽  
Small Fruit ◽  
Marketable Fruit

Fruit size declines in strawberries (Fragaria × ananassa Duch.) as the season progresses in many subtropical areas, possibly due to inadequate leaf area, over-cropping, or high temperatures. An experiment was conducted to investigate the importance of these factors on fruit growth in ‘Festival’ in Queensland, Australia. Groups of plants were defoliated to remove half of the mature leaves on each plant, thinned to remove all the inflorescences on each plant, or defoliated and thinned. Control plants were left intact. Defoliation, thinning, or defoliation + thinning decreased yield (total and/or marketable) by 15% to 24% compared with the control. Defoliation, or defoliation + thinning decreased average fruit weight (total and/or marketable fruit) by 1 to 2 g compared with the control, whereas thinning had the opposite effect. The incidence of small fruit increased towards the end of the season. There were strong relationships between fruit weight and average daily mean temperature in the seven weeks before harvest (R2s greater than 0.80). Fruit weight decreased from 24 g to 8 g as the temperature increased from 16 °C to 20 °C. This response was not affected by defoliation or thinning. The strong effect of temperature on fruit size indicates a problem for production in the future in the absence of heat-tolerant cultivars.

scholarly journals 657 Relationship between Intensity of Flowering and Cropping in Fruit and Nuts

HortScience ◽  
1999 ◽  
Vol 34 (3) ◽  
pp. 561C-561
Author(s):  
E.W. Stover
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Commercial Application ◽  
Critical Periods ◽  
Alternate Bearing ◽  
Crop Species ◽  
Fruit Thinning ◽  
Small Fruit ◽  
Substantial Investment ◽  
Flowering Intensity

The relationship between intensity of flowering and various aspects of cropping will be reviewed for fruit and nuts. Clearly, relatively light flowering can limit yield in most fruit and nut species. This commonly occurs before mature bearing commences and in “off” years for varieties that display alternate bearing. During mature bearing, many species will carry fruit numbers that exceed commercially desired levels, resulting in excessively small fruit and accentuating alternate bearing. The economic disadvantages of excess cropload have resulted in considerable research on fruit thinning and widespread commercial application of this practice. Heavy flowering intensity in some crop species results in economic disadvantages beyond the problems of excessive cropload and resultant small fruit size. Many species flower profusely and have initial fruit set far in excess of final tree capacity, resulting in abscission of numerous flowers and fruitlets. Abscised organs can represent a substantial investment in carbohydrates and nutrients, compromising availability at critical periods in flower and fruit development. The potential implications of this process are best exemplified in navel orange, where an increase in flowering beyond intermediate intensity results in a reduction in both initial fruit set and final fruit yield at harvest. In several crops, there is evidence that fruit size may be reduced by excessive flowering, even when cropload is quickly adjusted to an acceptable level. These data suggest that further research on the advantages of controlling flowering intensity is warranted.

scholarly journals APPLE FRUIT CHEMICAL THINNING IN CHIHUAHUA, MÉXICO

2008 ◽  
Vol 31 (3) ◽  
pp. 243
Author(s):  
David I. Berlanga-Reyes ◽  
Alejandro Romo-Chacón ◽  
Ángel R. Martínez-Campos ◽  
Víctor M. Guerrero-Prieto
Keyword(s):  
Fish Oil ◽  
Fruit Set ◽  
Fruit Size ◽  
Apple Fruit ◽  
Naphthalene Acetic Acid ◽  
Alternate Bearing ◽  
Fruit Thinning ◽  
Equatorial Diameter ◽  
Large Trees ◽  
Golden Delicious

Chemical fruit thinning is a common practice in apple (Malus x domestica Borkh.) orchards for achieving high quality fruits, reduced costs of hand-thinning and promote return of flowering. Hand thinning is a common and high cost practice, not only due to the labor involved, but also because seedling and vigorous clonal rootstocks result in large trees. The chemical thinning agents: Ethephon (ETH), Carbaryl (CB), Naphthalene acetic acid (NAA), 6- Benzyladenine (6-BA), and fish oil were evaluated on ‘Golden Delicious’ and ‘RedChief Delicious’ apple trees in 2004 and 2005. Chemical thinning effect was compared with early and late handthinnings. Treatments were sprayed when the biggest fruit in the clusters was 10 mm in equatorial diameter. NAA showed the best effect in reducing final fruit set in both cultivars and years evaluated, with results comparable to those of early hand-thinning (thinned when king-fruit size was 10 mm) in ‘Golden Delicious’ trees. In ‘RedChief Delicious’, fruit set reduction by NAA, fish oil and CB treatments was similar to early hand-thinned trees only in 2005. In 2005, time spent during supplementary hand-thinning in ‘Golden Delicious’ trees was reduced by chemical thinning treatments, except by fish oil; whereas in ‘RedChief Delicious’ only NAA K-salt reduced it in 2004. An increase in fruit equatorial diameter was observed only in 2004 with NAA and fish oil. Alternate bearing, typical of ‘Golden Delicious’, was not diminished by these chemical thinning treatments.

scholarly journals The Potential Use of Metamitron as a Chemical Fruit-thinning Agent in Mandarin

2018 ◽  
Vol 28 (1) ◽  
pp. 28-34 ◽  
Author(s):  
Ockert P.J. Stander ◽  
Johané Botes ◽  
Cornelius Krogscheepers
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Fruit Trees ◽  
Fruit Yield ◽  
Citrus Reticulata ◽  
Alternate Bearing ◽  
Fruit Thinning ◽  
Total Carbohydrates ◽  
Leaf Carbohydrates ◽  
Potential Use

Under conditions of profuse flowering and excessive fruit set, citrus (Citrus sp.) fruit need to be thinned to increase the size of remaining fruit, reduce the intensity of alternate bearing, or both. Metamitron was recently developed as a chemical fruit-thinning agent for apple (Malus ×domestica) and pear (Pyrus communis), and it inhibits photosynthesis and is thought to transiently reduce the carbohydrate pool in fruit trees. Citrus trees are sensitive to carbohydrate stress during and immediately after flowering, but the response of citrus to foliar treatment with a photosynthesis inhibitor, such as metamitron, is unknown. The purpose of this study was to evaluate metamitron for its effects on leaf carbohydrates and its ability to chemically thin citrus fruitlets. Significant fruit-thinning effects were found in all the experiments conducted over two seasons. A 300 mg·L−1 metamitron treatment reduced leaf sugars and leaf total carbohydrates, and consistently reduced the total number of fruit per tree in both seasons in ‘Nadorcott’ mandarin (Citrus reticulata), irrespective of the timing of application. In the second season, a reduction in fruit yield was reported with an increase in metamitron concentration, both in mass and number of fruit per tree. A 150 mg·L−1 metamitron treatment in November had no fruit-thinning effects, and fruit yield was not different from the control. The application of metamitron did not increase the fruit size of ‘Nadorcott’ mandarin and had no direct effect on other fruit quality attributes in either season. Metamitron can be used as a chemical fruit-thinning agent to reduce fruit numbers in ‘Nadorcott’ mandarin, but an increase in fruit size or quality should not be expected.

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

2006 ◽  
pp. 29-35 ◽  
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.

scholarly journals Cropping and Fruit Growth in Redchief `Delicious': An Analysis of the Effect of NAA and Cytokinins

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 525A-525
Author(s):  
Martin J. Bukovac ◽  
John C. Neilsen ◽  
Jerome Hull
Keyword(s):  
Fruit Size ◽  
High Volume ◽  
Inhibitory Effect ◽  
Tree Age ◽  
Marked Variation ◽  
Crop Load ◽  
Fruit Thinning ◽  
Single Tree ◽  
Small Fruit ◽  
Effect On Yield

Generally, NAA is effective in inducing fruit thinning in `Delicious'. Although significant thinning may be induced, fruit size at harvest may not be closely related to crop load. Further, the magnitude of response to NAA may vary markedly between seasons. Herein, we present an analysis of response of `Redchief Delicious' over several years (tree age 11–14 years old) to high-volume sprays of NAA (15 mg·L–1), BA (25-50 mg·L–1), and CPPU (5 mg·L–1) at KFD of 8–12 mm. A single tree was used for each treatment replicated four to six times and response was measured by yield and fruit size distribution for each tree. In eight experiments over 4 years, NAA resulted in an average 22% reduction in yield, a 5.1% reduction in large fruit (70 mm+) and 2% reduction in small (<64 mm) fruit compared to NTC. There was a marked variation in response among years. Over 4 years, BA averaged a 5% decrease in yield, a 15% increase in large fruit and a 21% decrease in small fruit. In contrast, when NAA was combined with BA at 25-50 mg·L–1, yield decreased an average of 30%, large fruit decreased by 68%, and small fruit increased 8-fold (2.54 vs 20.6 kg/tree). CPPU alone (2-year study) had no significant effect on yield, but increased large fruit by 60% and significantly reduced production of small fruit. When CPPU was combined with NAA, yield was reduced in both years and the amount of large fruit was increased in 1995, but decreased in 1996. NAA had a very inhibitory effect on fruit size in 1996. One explanation may be that the crop was produced by lateral fruit (king flowers were lost to frost), and NAA has a greater inhibitory effect on lateral than king fruit. Results will be discussed in relation to studies with `Jonathan' and `Empire'.

scholarly journals Native Variation in Bloom and Crop Density in Spur-type `Delicious' and Effect of Ethephon Applied in High Crop Years

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1096D-1097
Author(s):  
Martin J. Bukovac ◽  
Jerry Hull ◽  
Paolo Sabbatini
Keyword(s):  
Apple Tree ◽  
Cultural Practices ◽  
Total Yield ◽  
Fruit Size ◽  
Alternate Bearing ◽  
Full Bloom ◽  
Crop Load ◽  
Fruit Thinning ◽  
Crop Density ◽  
Return Bloom

For studies on blossom/fruit thinning in apple, tree selection is often based on uniformity of bloom/crop load, assuming that such trees exhibit greater uniformity to treatment. However, the literature is replete with data showing marked variation for a given treatment. We followed variation in bloom/crop density of spur-type `Delicious'/MM.106 and effect of ethephon applied in high crop years on return bloom/yield. Uniform trees (n = 95), under identical cultural practices, were selected for varying crop load. Return bloom, yield and fruit size were monitored over six years. General mean (X) for yield was 94 ± 25 kg/tree and bloom density, rated 1 to 10 (highest), was 5.4 ± 1.7. Annual yield deviated from X by +56 to –40% and bloom density by +49 to –42%. All trees were ranked (decreasing yield) and assigned to five percentile (PCTL) groups (1st, 81-100; 2nd, 61-80; 3rd, 41-60; 4th, 21-40; 5th, 0-20 kg/tree). Trees in each group were reassigned annually to the five PCPL groups for the next five years. Of trees in 1st PCTL (n = 19, X = 187 ± 10 kg/tree) in year one, 5, 5, 24, 0 and 63% placed in PCPL 1, 2, 3, 4, and 5, respectively, in year two. Of trees in 1st PCTL (5%) in year two, all placed in PCTL 2 in year three. Effect of ethephon [200 mg·L-1 at 3, 3 + 6, 3 + 6 + 9 weeks after full bloom (WAFB)] applied in on years to `Redchief', with strong alternate bearing, were evaluated for six years. Ethephon at 3 WAFB had no effect. Yield from multiple applications differed from control (NTC) in off years, but not from each other. Total yield (3 on + 3 off years) for the NTC and ethephon at 3 + 6 WAFB was similar (479 vs. 471 kg/tree). However, 64% of the total yield was produced in the on years and 36% in the off years in NTC vs. 56 and 44% in 3 + 6 WAFB, respectively.

scholarly journals Effects of Application Conditions and Adjuvants on Chemical Fruit Thinning of Apple

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 525B-525
Author(s):  
E.W. Stover ◽  
M.J. Fargione ◽  
R.A. Risio ◽  
C.I. Mulvihill
Keyword(s):  
High Temperature ◽  
Fruit Size ◽  
Naphthalene Acetic Acid ◽  
Seed Number ◽  
Apple Trees ◽  
Cross Sectional ◽  
Drying Time ◽  
Fruit Thinning ◽  
Cool Conditions ◽  
Spray Treatment

In 1995, effects of adjuvants on fruit thinning with Accel [10:1 ratio of 6-benzyladenenine (BA):GA4&7] at 75 ppm BA were studied. Silwet L-77 was used at 0.027% (v/v). Regulaid and ultrafine spray oil were used at 0.125% (v/v). Treatments also included unthinned controls, NAA (naphthalene acetic acid) at 7.5 ppm plus 600 ppm carbaryl, and Accel plus 600 ppm carbaryl. `Empire' apple trees on M.9/MM.111 rootstock in Milton, N.Y., were used in the 6th leaf. Trees were blocked by number of blossom clusters/cm2 trunk cross sectional area. Applications were made at 1.5x concentration, using tree-row volume to calculate appropriate dilute volume. Each spray treatment was applied near the high temperature on each of three consecutive days around 10-mm king fruitlet diameter. Conditions were as follows: day 1–high temperature of 19°C with moderate drying time, and rain several hours after application; day 2–high temperature of 15.5°C and prolonged drying; and day-3–high temperature of 21.1°C and moderate drying. All treatments significantly thinned and enhanced fruit size compared to unthinned controls. Application conditions (treatment day) did not significantly affect response when compared within any spray treatment. However, in combined analyses, treatment with Accel or Accel with Regulaid resulted in significantly smaller fruit on day 1, when rain followed application, compared to these treatments on other days, or compared to Accel with other adjuvants on day 1. Accel with carbaryl resulted in largest fruit size and cropload reduction, but significantly reduced seed number/fruit. It is postulated that prolonged drying times occurring in cool conditions can compensate for reduced uptake rate at lower temperatures.

scholarly journals 186 INFLUENCE OF HYDROGEN CYANAMIDE AND WILTH IN ON BLOSSOM THINNING OF APPLE AND PLUM

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 455f-455
Author(s):  
Esmaeil Fallahi ◽  
Brenda R. Simons ◽  
Max W. Williams
Keyword(s):  
Fruit Quality ◽  
Fruit Set ◽  
Fruit Size ◽  
Soluble Solids ◽  
Full Bloom ◽  
Mature Trees ◽  
Hydrogen Cyanamide ◽  
Fruit Thinning ◽  
Yield And Quality

Effects of hydrogen cyanamide and Wilthin on blossom thinning and the consequences of thinning on fruit set, yield and fruit quality of `Rome Beauty' was studied. A full bloom application of hydrogen cyanamide at the rate of 0.25% (Dormex formulation) or 0.25% of Wilthin both followed by a fruit thinning by Sevin + NAA effectively thinned mature trees of `Rome Beauty' and had a similar effect on fruit set, yield and fruit quality. The effects of these two chemicals at these rates on several aspects of fruit set, yield and quality were similar to the effects of Elgetol. Hydrogen cyanamide, Elgetol and 0.25% Wilthin at full bloom resulted in a higher percentage of single fruit set, thus, less labor for hand thinning. Application of 0.37% Wilthin at 20% bloom or at full bloom resulted in larger fruit size, but induced fruit russetting. Soluble solids of fruit from trees with Elgetol, 0.37% Wilthin at 20% bloom or at full bloom were higher than fruit from other treatments. Hydrogen cyanamide at 0.50% resulted in a satisfactory level of blossom thinning in `Friar' plums.

Sign in / Sign up

Export Citation Format

Share Document