scholarly journals Comparison of NAA and Carbaryl Petal-fall Sprays on Fruit Set of Apples

1993 ◽  
Vol 3 (4) ◽  
pp. 428-429 ◽  
Author(s):  
Max W. Williams
Keyword(s):  
Side Effects ◽  
Fruit Set ◽  
Apple Trees ◽  
Early Application ◽  
Adverse Side Effects ◽  
Biennial Bearing ◽  
Fruit Thinning ◽  
Curled Leaves

Biennial bearing of apple trees can be overcome either by the use of a blossom chemical thinner or by early application of a postbloom thinner. Carbaryl (Sevin) is a post-bloom fruit-thinning chemical with an effective thinning period of 4 to 5 weeks after bloom. Sevin was compared in 1992 and 1993 with NAA as an early petal-fall spray. Sevin treatments reduced fruit set to one fruit per cluster with no adverse side effects on the foliage. NAA inconsistently reduced fruit set and the remaining fruit were in clusters, The NAA-treated foliage was adversely affected; having small curled leaves. NAA at 10 ppm under-thinned in 1992 and seriously over-thinned in 1993, whereas Sevin treatments were consistent for fruit thinning in both years. Sevin applied at petal-fall or at petal-fall + 7 days effectively reduced fruit set and reduced fruit competition.

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.

The Influence of Temperature and Low Light on Fruit Set and Chemical Thinning of Apple Trees

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 452e-453 ◽  
Author(s):  
R.E. Byers
Keyword(s):  
Fruit Set ◽  
Dark Period ◽  
Light Stress ◽  
Fruit Trees ◽  
Low Light ◽  
Apple Trees ◽  
Natural Sunlight ◽  
Fruit Thinning ◽  
Growth Chambers ◽  
Low Light Stress

Fruit trees grown in the eastern U.S. environment are typically exposed to low light conditions from cloudy/rainy periods that can reduce PAR to 10% to 15% of full sun for 2 to 3 days. To magnify or concentrate the effect of temperature during low light stress, fruit trees were moved from the field into total darkness for 2 to 4 days at various temperatures and then returned to the field. This provided low light stress while eliminating the need for treatments involving various levels of light and temperature during the day on photosynthesis. To reduce transplanting shock, bearing apple trees used were grown in the field in 25-cm-diameter root bags and were on M.27 rootstock. After initial fruit set (at about 15 mm fruit diameter) trees were dug and transplanted into 5-gal buckets and moved for short periods of time (2 to 4 days) into various dark environments or sprayed with various thinning chemicals and placed in growth chambers at 5, 10, 16, and 21 °C in the dark. Immediately after dark treatments, trees were returned to the field and placed in the original holes. In 1995, we found that Elstar/M.27 apple trees placed in the dark for 3 or 4 days and returned to natural sunlight conditions abscised all of their fruit at 21 °C dark temperature but were retained at 5 °C. In 1996, we found that Braeburn/M.27 apple trees placed in the dark for 2 days and returned to natural sunlight conditions abscised all of their fruit at 16 and 21 °C dark temperature, but were retained if the dark period was 5 °C. These data indicated that the dark period temperature was very important for fruit retention. In addition, trees sprayed with Carbaryl+Accel 3 h before placing in the growth chambers caused the development of more pigmy fruit at all temperatures. Pigmy fruit also appeared to be related to the combined effects of digging trees, treating with Carbaryl + Accel, and colder temperatures. In 1997, we found that Stayman/M.27 apple trees placed in the dark for 2 days and returned to natural sunlight conditions abscised most of their fruit at 21 °C dark temperature, but were retained if the dark period was 5 °C. Fruit thinning occurred at 10 and 16 °C. Additional fruit thinning was significantly promoted by Carbaryl or NAA + Regulaid over the range of temperatures (5 to 21 °C), but thinning appeared to be most promoted at 21 °C dark temperature. Unexpectedly, ethephon caused fruit thinning at all temperatures from 5 to 21 °C, and thinning did not appear to be affected by temperature (ethephon defruited all trees at all temperatures). We suspect that higher dark temperatures caused either higher respiration rates or higher natural ethylene production, which promoted fruit abscission whether treated with a thinner or not. In one field experiment, Carbaryl sprays were applied at 2-h intervals beginning at 6 a.m. until 8 p.m. to Empire/Mark trees. Similar fruit thinning occurred when applied at temperatures ranging from 18 to 36 °C. These data suggest that no differences in thinning were related to daytime temperature.

Different Sources and Concentrations of 6-BA in Chemical Thinning of Post-flowering in Apple Trees

2019 ◽  
pp. 1-9
Author(s):  
Gentil Carneiro Gabardo ◽  
José Luiz Petri ◽  
Aike Anneliese Kretzchmar ◽  
Mariuccia Schlichting De Martin ◽  
André Amarildo Sezerino ◽  
...  
Keyword(s):  
Fruit Set ◽  
Apple Tree ◽  
Block Design ◽  
Fruit Size ◽  
Growing Season ◽  
Apple Trees ◽  
Histological Changes ◽  
Fruit Thinning ◽  
Randomized Block Design ◽  
Different Sources

Aims: Evaluate the efficiency of sources and dosages of 6-benzyladenine in the chemical thinning of the apple tree ‘Fuji Suprema’, as well as possible histological changes in the fruits produced, in the Midwestern region of the state of Santa Catarina. Study Design: The experiment was arranged in a randomized block design and replicated six replications. Place and Duration of Study: The experiment was carried out in the municipality of Caçador, Brazil (latitude 26º46 'S, longitude 51º W, altitude 960 meters), during the growing season of 2016/2017. Methodology: Two commercial products based on 6-BA (Benzyladenine), Exilis® and Maxcel®, both with 2% BA in their composition, were tested and applied individually in post-flowering period (in fruits of 5-10 mm), which were compared with plants with no thinning and manual thinning. Treatments were as follows: Control (no thinning); manual thinning; Exilis® (1.5, 3.0, 4.5 and 6.0 L ha-1) and Maxcel® 4.5 L ha-1), using a spray volume equivalent to 1000 L ha-1. The fruit set and the number of fruit per cm2 branch, was reduced in treated plants, regardless of the concentration of BA or formulation used. The productivity ranged from 38 to 56.5 t ha-1 in the treatments of Exilis®, 60.5 t ha-1 in manual scaling and 24.5 t ha-1 in the Maxcel® 4.5 L ha-1, characterizing excessive thinning. BA is efficient in fruit thinning in 'Fuji Suprema' apple trees, being the reduction of fruiting, and increase of fruit size, proportional to the applied concentration. There may be differentiated efficiency of the product by its formulation, even though they have concentrations of active ingredient equivalent. Exilis® was efficient in thinning of apple "Fuji Supreme", when applied to fruit 5 to 10 mm in diameter reduced the need for manual thinning, without causing toxicity. BA can promote the increase in the cell density of fruits produced in proportion to the applied concentration.

scholarly journals METAMITRON REPLACING CARBARYL IN POST BLOOM THINNING OF APPLE TREES

2016 ◽  
Vol 38 (4) ◽  
Author(s):  
JOSÉ LUIZ PETRI ◽  
MARCELO COUTO ◽  
GENTIL CARNEIRO GABARDO ◽  
POLIANA FRANCESCATTO ◽  
FERNANDO JOSÉ HAWERROTH
Keyword(s):  
Acetic Acid ◽  
Experimental Design ◽  
Standard Treatment ◽  
Fruit Set ◽  
Naphthalene Acetic Acid ◽  
Single Plant ◽  
Fresh Weight ◽  
Apple Trees ◽  
Fruit Thinning ◽  
Apple Cultivars

ABSTRACT Carbaryl or the mixture of carbaryl with NAA (naphthalene acetic acid) or BA (benzyladenine) are the post-bloom chemical thinners most widely used in apple thinning in Brazil. The marketing restriction of carbaryl demands new options of apple post-bloom thinners, requiring the evaluation of others compounds for this purpose. Metamitron is one of the substances that may be used in chemical thinning of apples. Metamitron was evaluated at two concentrations, alone or in mixture with BA, in ‘MaxiGala’, ‘Fuji Suprema’ and ‘Fred Hough’ apple cultivars. Applications of metamitron at 384 mg L-1 and at 768 mg L-1 in a mixture with BA, ranging from 40 mg L-1 to 80 mg L-1, sprayed on fruits with diameter ranging from 5 to 25 mm were compared with the standard treatment and hand thinning. The experimental design was a randomized complete block with 4-6 repetitions of a single plant. The variables analyzed were: fruit set (%); percentage of floral clusters with 1, 2, 3, 4 or more fruits; fruit yield (kg); average fruit fresh mass (g) and percentage of dropped fruit after thinning. Metamitron alone or in combination with BA reduced production per plant and significantly increased the fresh weight of fruits in all cultivars tested. Metamitron at 800 mg L-1 resulted in excessive fruit thinning, especially in ‘MaxiGala’ cultivar. Metamitron or metamitron + BA have potential to compose the program of chemical thinning of apple trees to replace carbaryl.

scholarly journals Response of Royal Gala apples to multiple applications of chemical thinners and the dynamics of fruitlet drop

2019 ◽  
Vol 99 (1) ◽  
pp. 1-11 ◽  
Author(s):  
John A. Cline ◽  
Catherine J. Bakker ◽  
Amanda Gunter
Keyword(s):  
Fruit Set ◽  
Regulatory Mechanism ◽  
Single Application ◽  
Apple Trees ◽  
Fruit Thinning ◽  
Fruit Drop ◽  
Crop Density ◽  
Marketable Size ◽  
Fruitlet Abscission ◽  
Fruit Load

Apple trees bear an abundance of flowers that 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 fruit thinning is usually required to optimize economic fruit load and annual bearing. This 2 yr study investigated the response of Royal Gala apple trees to primary single and combination sprays of 6-benzyladenine (6-BA) and carbaryl during fruit set, followed by secondary sprays of either treatment 7 d later. The objective was to determine the effect of a second application of chemical thinner on fruitlet abscission, which compounds are most efficacious, and to characterize the pattern of fruitlet drop. The combinations of chemical thinners varied in their effectiveness at reducing crop density. About 12–14 d were required from the time of the first application of chemical thinner to observed fruitlet beneath trees. A single application of both thinners applied at 8 mm advanced fruit drop by 7 d in most instances. The tank-mix of 6-BA and carbaryl applied at 8–10 mm followed by a secondary spray of carbaryl at 15 mm was the most efficacious thinning combination. Secondary sprays of 6-BA at 15 mm were ineffective at inducing additional fruit drop. Combination sprays of 6-BA and carbaryl were more effective than repeat sprays of the same product. This study enhances our understanding of the dynamics of fruitlet abscission and the benefits of multiple applications of post-bloom chemical thinners.

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.

Seasonal wound presence and susceptibility to Neonectria ditissima infection in New Zealand apple trees

2015 ◽  
Vol 68 ◽  
pp. 250-256 ◽  
Author(s):  
N.T. Amponsah ◽  
M. Walter R.M. Beresford ◽  
R.W.A. Scheper
Keyword(s):  
New Zealand ◽  
Artificial Inoculation ◽  
Early Winter ◽  
Leaf Fall ◽  
Apple Orchards ◽  
Apple Trees ◽  
Leaf Scar ◽  
Fruit Thinning ◽  
Different Types

Leaf scar wounds are important sites for Neonectria ditissima infection of apple trees Monitoring leaf fall in Scilate/Envy and Braeburn trees to estimate leaf scar wound presence showed maximum leaf scar incidence occurred in June (early winter) Wounds detected in New Zealand apple orchards were bud scale scars fruit thinning and picking wounds leaf scars and pruning cuts Picking wounds are caused during harvest where the pedicel is detached from the shoot Susceptibility of these different types of wounds was determined using artificial inoculation of N ditissima conidia during the season Pruning cut wounds were the most susceptible followed by fruit picking and thinning wounds and the least susceptible were leaf scar wounds No infections were observed when bud scale wounds were inoculated There was no difference in wound susceptibility between cultivars but overall Scilate/Envy wounds developed more lesions than Braeburn wounds

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