scholarly journals Apple Thinning by Photosynthetic Inhibition

1990 ◽  
Vol 115 (1) ◽  
pp. 14-19 ◽  
Author(s):  
R.E. Byers ◽  
J.A. Barden ◽  
R.F. Polomski ◽  
R.W. Young ◽  
D.H. Carbaugh
Keyword(s):  
Tree Growth ◽  
Shoot Growth ◽  
Fruit Set ◽  
Full Bloom ◽  
Apple Trees ◽  
Fruit Abscission ◽  
Hand Pump ◽  
Photosynthetic Inhibition ◽  
Fruit Thinning ◽  
Leaf Yellowing

Shading (92%) of `Redchief Delicious' apple (Malus domestics Borkh.) trees for 10-day periods from 10 to 20, 15 to 25, 20 to 30, and 25 to 35 days after full bloom (DAFB) caused greater fruit abscission than shading from 5 to 15, 30 to 40, 35 to 45, or 47 to 57 DAFB. Fruit 8 to 33 mm in diameter (10 to 30 DAFB) were very sensitive to 10 days of shade, even though fruit sizes of 6 to 12 mm are considered the most sensitive to chemical thinners. In a second test, shading for 3 days caused fruit thinning; 5 days of shade in the periods 18 to 23, 23 to 28, and 28 to 33 DAFB caused greater thinning than 11 to 16 or 33 to 38 DAFB. Shading reduced photosynthesis (Pn) to about one-third that of noncovered trees. Terbacil (50 mg·liter-1) + X-77 surfactant (1250 mg·liter-1) applied with a hand-pump sprayer 5, 10, or 15 DAFB greatly reduced fruit set and caused some leaf yellowing, particularly in the earliest treatments. Terbacil reduced Pn by more than 90% at 72 hours after application. Shoot growth of trees defruited by shade or terbacil was equivalent to defruited or deblossomed trees; ethephon (1500 mg·liter-1) inhibited tree growth and defruited trees. No terbacil residues were dectected in fruit at harvest from applications made 5, 15, 20, 25, or 30 DAFB. Eleven of 12 photosynthesis-inhibiting herbicides were also found to thin `Redchief Delicious' apple trees. Shading caused more thinning than terbacil at the later applications, which may reflect poorer absorption and/or lesser photosynthetic inhibition than when terbacil was applied to older leaves.

scholarly journals Controlling Growth of Bearing Apple Trees with Ethephon

HortScience ◽  
1993 ◽  
Vol 28 (11) ◽  
pp. 1103-1105 ◽  
Author(s):  
Ross E. Byers
Keyword(s):  
Tree Growth ◽  
Phosphonic Acid ◽  
Fruit Set ◽  
Diameter Ratio ◽  
Soluble Solids ◽  
Full Bloom ◽  
Apple Trees ◽  
Fruit Abscission ◽  
Solids Concentration ◽  
Soluble Solids Concentration

Ethephon applied 12 to 26 days after full bloom at 1000 to 1500 mg·liter-1 not only substantially inhibited apple (Malus domestia Borkh., spur `Delicious' strains) tree growth but also caused fruit abscission. Gibberellin plus ethephon did not prevent fruit abscission when ethephon was used at these rates. Several low weekly doses of ethephon controlled tree growth without causing fruit abscission. Ethephon increased fruit soluble solids concentration and substantially reduced fruit starch in the application year. Ethephon greatly increased flowering and fruit set the following season. Fruit length: diameter ratio was not altered by the previous seasons' low weekly doses of ethephon. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).

Thinning response of ‘Redhaven’ peaches to 1-aminocyclopropane carboxylic acid (ACC)

2020 ◽  
pp. 1-13
Author(s):  
John A. Cline ◽  
Catherine J. Bakker ◽  
Amanda Beneff
Keyword(s):  
Carboxylic Acid ◽  
Fruit Set ◽  
Total Yield ◽  
Fruit Size ◽  
Fruit Weight ◽  
Full Bloom ◽  
Fruit Thinning ◽  
Leaf Yellowing ◽  
Peach Trees ◽  
Fruit Load

Peach trees bear an abundance of flowers which produce a surplus of fruit that the tree is unable to support. A self-regulatory mechanism enhances the abscission of immature fruitlets leading to a reduced fruit load, but this is often insufficient to achieve fruit of marketable size. Supplementary manual fruit thinning is typically required to optimize economic fruit load. This 2-yr study investigated the response of ‘Redhaven’ peach trees to sprays of 300 and 600 mg L−1 1-aminocyclopropane carboxylic acid (ACC) during the phenological stages of full bloom, shuck split, and ∼20 mm fruitlet diameter. The objective was to determine the efficacy of ACC on fruit set, fruit size, and yield at harvest and the amount of hand-thinning required at “June drop”. Although the response to ACC varied between the 2 yr, 600 mg L−1 ACC spray at full bloom (2018) and at ∼20 mm fruit size (2019) reduced fruit set, the need for hand-thinning by 59%–66%, and crop load. Treatments also had varying but significant effects on leaf yellowing and leaf drop when measured shortly after application. ACC reduced total yield and number of fruit per tree in both study years and increased fruit weight in 2019. Overall, peaches were responsive to ACC at a range of timings from bloom to ∼20 mm fruit size. This study enhances our understanding of ACC on fruitlet abscission of peaches and is one of few studies to demonstrate the effectiveness of a chemical fruitlet thinner for peaches.

scholarly journals (99) Using Naphthalene Acetic Acid, Prohexadione-Ca, Ethephon, and Scoring to Reduce Vegetative Growth in Upper Canopy of Apple Trees

HortScience ◽  
2006 ◽  
Vol 41 (4) ◽  
pp. 1030C-1030
Author(s):  
Wesley R. Autio ◽  
James Krupa ◽  
Jon M. Clements ◽  
Duane W. Greene
Keyword(s):  
Acetic Acid ◽  
Vegetative Growth ◽  
Shoot Growth ◽  
Fruit Set ◽  
Extension Growth ◽  
Naphthalene Acetic Acid ◽  
Full Bloom ◽  
Treatment Area ◽  
Latex Paint ◽  
Apple Trees

In 2004, at full bloom, 3-year-old `Cameo'/G.16, `Gala'/M.9 NA-KBT337, `Gala'/G.16, and `Redmax'/B.9 apple trees were treated with naphthalene acetic acid (NAA, 1.5% in latex paint) in a 7.5-cm band completely around the central leader at the base of 2-year-old wood. NAA treatment reduced 2004 extension growth of the central leader by 14% and total shoot growth above the treatment area by 32%. `Cameo'/G.16 trees also were sprayed with prohexadione-Ca (250 ppm with surfactant and water conditioner) at full bloom, and additional trees were sprayed with ethephon (500 ppm with surfactant) 1 week after full bloom. These spray treatments were made only to the stems and foliage from the base of the central leader's 2-year-old wood to the top of the canopy. Ethephon reduced total shoot growth in 2004 by 26%, and prohexadione-Ca reduced it by 63%. Prohexadione-Ca also reduced fruit set of `Cameo' in 2004. Scoring (single knife cut completely around the circumference of the trunk) at the base of the 2-year-old wood in the `Cameo' trees resulted in a 23% reduction in leader growth and a 22% in totals shoot growth in the upper canopy in 2004. In 2005 at full bloom, 4-year-old `Golden Delicous'/B.9 trees were treated with NAA similarly to trees in 2004, except treatment at the base of 2-year-old wood was compared to treatment at the base of 1-year-old wood. Treating the base of 1-year-old wood reduced growth to a greater degree than comparable treatment at the base of 2-year-old wood. For the 1- and 2-year-old-wood treatments, the number of laterals produced from the 1-year-old wood was reduced 42% and 17%, and total shoot growth from 1-year-old wood was reduced by 49% and 31%, respectively.

scholarly journals Ethylene Evolution from Detached Apple Spurs in Response to Chemical Thinners

HortScience ◽  
2002 ◽  
Vol 37 (4) ◽  
pp. 662-665 ◽  
Author(s):  
Steven J. McArtney
Keyword(s):  
Phosphonic Acid ◽  
Fruit Set ◽  
Average Diameter ◽  
Naphthaleneacetic Acid ◽  
Similar Amount ◽  
Full Bloom ◽  
Ethylene Evolution ◽  
Apple Trees ◽  
Fruit Abscission ◽  
Initial Drop

Ethylene evolution from detached fruiting apple spurs was measured after application of various bloom and post-bloom thinning agents. Ethylene evolution from fresh detached spurs of `Splendor' apple trees increased one day after application of a bloom thinning spray of ethephon or NAA, and remained higher than rates of ethylene evolution by detached spurs from unsprayed control trees for 6 (NAA) or 10 (ethephon) days. Both ethylene evolution and fruit abscission during the initial drop period were higher on trees treated with ethephon compared to NAA, however final fruit set was similar for these two treatments. Ethylene evolution was significantly higher following NAA application onto `Fuji' trees compared with NAAm, but final fruit set was reduced by a similar amount (≈20%) for both of these materials. Application of BA to `Pacific Rose™' apple trees when the average diameter of spur fruit was either 4 mm (6 days after full bloom) or 7 mm (12 days after full bloom) resulted in a significant increase in the rate of ethylene evolution and also reduced final fruit set. When application of BA was delayed until the average diameter of spur fruit was 14 mm (24 days after full bloom) neither the rate of ethylene evolution or final fruit set was affected. Although an increase in the rate of ethylene evolution was a prerequisite for thinning in the present experiments, the magnitude of this increase was not related to the final thinning efficacy. Chemical names used: benzyladenine (BA); 2-chloroethyl phosphonic acid (ethephon); naphthaleneacetic acid (NAA); naphthalene acetamide (NAAm).

Studies on the fruit thinning effect of N.A.A. and some carbamates on Jonathan and Delicious apples

1975 ◽  
Vol 15 (74) ◽  
pp. 424
Author(s):  
N Veinbrants
Keyword(s):  
Fruit Set ◽  
Full Bloom ◽  
Time Of Application ◽  
Fruit Thinning ◽  
Bloom Period ◽  
Series Of Experiments ◽  
Thinning Effect

In a series of experiments in Victoria a single spray of the fungicide thiram applied shortly after full bloom reduced fruit density highly significantly on Jonathan and Delicious apples, but resulted in insufficient thinning. The fungicide Dithane M-45 caused mild thinning and the fungicide Dikar had no effect on fruit set when applied during post-bloom period on Jonathan apples. Applications of the insecticide carbamult applied 16, 23 and 32 days after full bloom reduced fruit density highly significantly and to about the extent as N.A.A. applied 16 days after full bloom on Jonathan apples. Carbamult caused the same degree of thinning irrespective of time of application. N.A.A. and carbamult resulted in adequate fruit thinning.

scholarly journals EFFECTS OF HYDROGEN CYANAMIDE ON APPLE AND PLUM FRUIT THINNING

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 690a-690
Author(s):  
Esmaeil Fallahi ◽  
Brenda R. Simons ◽  
John K. Fellman ◽  
W. Michael Colt
Keyword(s):  
Malus Domestica ◽  
Fruit Set ◽  
Fruit Size ◽  
Apple Fruit ◽  
Fruit Weight ◽  
Full Bloom ◽  
Hydrogen Cyanamide ◽  
Fruit Thinning ◽  
Prunus Salicina

Influence of various concentrations of hydrogen cyanamide (HC) on fruit thinning of `Rome Beauty' apple (Malus domestica Borkh.), `Friar,' and `Simka' plums (Prunus salicina Lindley) were studied. A full bloom application of HC at all tested concentrations decreased `Rome Beauty' apple fruit set and yield, and increased fruit weight. Hydrogen cyanamide at 0.25% (V/V) resulted in adequate apple thinning, indicated by the production of an ideal fruit weight. Prebloom and full bloom applications of HC at greater than 0.75% reduced plum fruit set and yield in `Friar.' Full bloom application of HC at 0.25% to 0.50% showed a satisfactory fruit set, yield, and fruit size in `Friar' plum. Full bloom application decreased fruit set and yield in `Simka' plum. Hand thinning, as well as chemical thinning, is recommended for plums.

scholarly journals EFFECTS OF SEVERAL GROWTH CONTROLLING TECHNIQUES ON APPLE TREES

HortScience ◽  
1992 ◽  
Vol 27 (11) ◽  
pp. 1162c-1162
Author(s):  
Wesley R. Autio ◽  
Duane W. Greene
Keyword(s):  
Tree Growth ◽  
Fruit Set ◽  
Fruit Size ◽  
Root Pruning ◽  
Apple Trees ◽  
The Third ◽  
Flesh Firmness ◽  
Bitter Pit ◽  
Spray Treatment

In 1991, experiments were conducted to assess the effects of several growth controlling techniques on tree growth and fruit set, abscision, ripening, and other qualities. The first two experiments assessed the effects of root pruning (4-8 days after petal fall, 1 m from the trunk, 30 cm deep) in commercial orchards. Compared to controls, root pruning reduced fruit abscision from mature `Cortland'/M.7A trees by 70% on 17 Sept. In another orchard, root pruning reduced fruit abscision from mature `McIntosh'/MM.106 trees by 47% on 24 Sept. The third experiment utilized vigorous `Gardiner Delicious'/MM.106 trees. Treatments included root pruning (as described above), trunk scoring (single, complete circle, approximately 40 cm from the soil), trunk ringing (single, complete circle, 1 mm wide, approximately 40 cm from the soil), ethrel spray treatment (500 ppm), and dormant-pruned and unpruned controls. Treatments were applied on 15 May, when terminal growth was 12-15 cm. No treatment affected fruit set. Trunk growth was less for ringed and scored trees than other treatments. Ringing and scoring advanced ripening compared to controls, and ethrel resulted in intermediate ripening. Treatments had no effect on fruit size, flesh firmness, or the development of bitter pit and cork spot. Fruit abscision was least from controls and root-pruned trees. Trees that were treated with ethrel in May had the most rapid abscision rate.

scholarly journals EFFECTS OF HYDROGEN CYANAMIDE ON STONE FRUIT THINNING

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1122a-1122
Author(s):  
Esmaeil Fallahi ◽  
Michael Colt ◽  
S. Krishna Mohan ◽  
John Fellman
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Stone Fruit ◽  
Severe Toxicity ◽  
Full Bloom ◽  
Hydrogen Cyanamide ◽  
Fruit Number ◽  
Fruit Thinning

Influence of prebloom and full bloom applications of hydrogen cyanamide on `Simka' and `Friar' plums in Southwest Idaho and `Florda Prince' peach in Southwest Arizona was studied. Prebloom application of 0.5% hydrogen cyanamide caused severe toxicity to the fruit buds in `Friar' lure, while 2% hydrogen cyanamide did not cause toxicity in `Simka' plum. `Simka' fruit was effectively thinned with 1-2% prebloom application. At full bloom, 1.5% hydrogen cyanamide caused severe flower and leaf burning in both `Friar' and `Simka' plums, while concentrations between 0.1% and 1% thinned flowers (fruits) in both of the plum cultivars. Influence of hydrogen cyanamide on final fruit set, fruit size and maturity are also studied. Prebloom or full bloom applications of 2% or 3% hydrogen cyanamide eliminated 95 to 100% of the blooms, while application of this chemical at 1% sufficiently thinned the fruit. Number of commercially packed large peaches in trees receiving 1% hydrogen cyanamide was the same as that in trees thinned by hand, suggesting hydrogen cyanamide as a potential chemical for stone fruit thinning.

scholarly journals Effects of the Fall Foliar Urea Application on N Reserves and Fruiting Performance of Gala/M26 Apple Trees in Pot-in-Pot System

HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 796A-796
Author(s):  
Pinghai Ding* ◽  
Minggang Cui ◽  
Leslie H. Fuchigami
Keyword(s):  
Fruit Set ◽  
Foliar Application ◽  
Fruit Size ◽  
Growing Season ◽  
Fruit Crops ◽  
Apple Trees ◽  
Fruit Thinning ◽  
Tree Fruit ◽  
Dormant Season ◽  
Foliar Urea

Reserve nitrogen is an important factor for plant growth and fruiting performance in tree fruit crops. The fall foliar urea application appears to be an efficient method for increasing N reserves. The effect of fall foliar urea application on N reserves and fruiting performance were studied with four year old `Gala'/M26 trees grown in 20 gallon containers in a pot-in-pot system from 2001 to 2003 at the Lewis-Brown Horticulture Farm of Oregon State Univ.. The trees were either sprayed with 0 or 2 times 3% urea after harvest in October. Shoot and spur samples were taken at the dormant season for reserve N analysis. Fruit performance was recorded in the following growing season. The fall foliar application significantly increased spur N reserve and had the trend to increase shoot N reserve but not significantly. The fall foliar application significantly increased tree fruit set and cluster fruit set. With normal fruit thinning, fall foliar urea application has the trend to increase both tree yield and average fruit size; without fruit thinning, fall foliar urea application has the trend to increase tree yield. These results indicate that fall foliar urea application an effective method to increase reserve N for maintaining tree yield.

Orchard soil management trials. 2. Effect of herbicides and nitrogen on growth and yield of young apple trees in permanent pasture

1971 ◽  
Vol 11 (48) ◽  
pp. 105 ◽  
Author(s):  
P Baxter ◽  
BJ Newman
Keyword(s):  
Tree Growth ◽  
Fruit Set ◽  
Fruit Size ◽  
Soil Management ◽  
Growth And Yield ◽  
Apple Trees ◽  
Narrow Strip ◽  
Permanent Pasture ◽  
Orchard Soil ◽  
Young Apple

On two cultivars of young apple trees growing in a permanent pasture, a narrow strip was kept bare with herbicide sprays used either during spring and summer or during the entire year. This increased tree growth, fruit set, fruit yield, and fruit size. Using more nitrogen fertilizer did not compensate for the grass competition and did not increase growth or yield as much as did the herbicide sprays. Most of the applied nitrogen could be accounted for in the increased growth of grass. The herbicide simazine increased tree growth more than other herbicides.

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