scholarly journals The Effect of Prohexadione-calcium on Fruit Set and Chemical Thinning of Apple Trees

HortScience ◽  
2007 ◽  
Vol 42 (6) ◽  
pp. 1361-1365 ◽  
Author(s):  
Duane W. Greene
Keyword(s):  
Vegetative Growth ◽  
Fire Blight ◽  
Fruit Set ◽  
Fruit Size ◽  
Load Level ◽  
Apple Trees ◽  
Management Tools ◽  
Crop Load ◽  
Prohexadione Calcium ◽  
Treated Apple

Prohexadione-calcium (ProCa) has emerged as one of the most important management tools that an orchardist has available to control vegetative growth and to reduce the incidence and severity of fire blight. It has also been implicated in increased fruit set on treated apple trees. This investigation was initiated to confirm the effects of ProCa on fruit set and to evaluate different thinning strategies that might be used to appropriately thin treated trees. ProCa increased fruit set when applied at petal fall at initial rates of 125 or 250 mg·L−1 in three of the four experiments described in this article. Thinners were applied before, at the time of, and after application of ProCa. In all experiments, chemical thinners did not reduce fruit set to the same crop load level on ProCa-treated trees as they did on untreated trees. It was concluded that a different and more aggressive chemical thinning strategy must be used on trees that were treated with ProCa. Fruit size was reduced on ProCa-treated trees. This reduction was usually, but not always, related to increased fruit set. ProCa increased the number of pygmy fruit on ‘Delicious’ apple trees.

scholarly journals The Effect of Repeat Annual Applications of Prohexadione–calcium on Fruit Set, Return Bloom, and Fruit Size of Apples

HortScience ◽  
2008 ◽  
Vol 43 (2) ◽  
pp. 376-379 ◽  
Author(s):  
Duane W. Greene
Keyword(s):  
Vegetative Growth ◽  
Fire Blight ◽  
Fruit Set ◽  
Fruit Size ◽  
Application Rate ◽  
Fruit Weight ◽  
Initial Application ◽  
Shoot Blight ◽  
Return Bloom ◽  
Prohexadione Calcium

Prohexadione–calcium (ProCa) is used routinely in orchards to control vegetative growth and to reduce the shoot blight phase of fire blight. This communication reports on multiple-year applications of ProCa with special emphasis on treatment effects on fruit set, fruit size, and return bloom. Increased fruit set was confirmed from high rates of ProCa above 125 mg·L−1. The increase in fruit set was attributed primarily to a reduction of abscission during June drop rather than an increase in initial set. ProCa decreased fruit weight in some instances. Part of this reduction could be attributed to increased fruit set. However, the large reduction in fruit weight at harvest could only be explained by a direct effect of ProCa when used at high rates. When ProCa was applied as a concentrate spray at 250 mg·L−1, terminal growth was reduced comparable to the application made as a tree row volume dilute spray (1×). However, fruit set was increased when the spray volume in which ProCa was delivered was reduced to 4×. A range of ProCa rates was used on ‘Mutsu’. An initial application rate of 42 mg·L−1 followed by similar subsequent rates controlled growth comparably to higher initial and total rates, yet low rates had no effect on fruit weight or return bloom. Low rates of ProCa appear to be effective at controlling vegetative growth yet appear to have minimal side effects. High rates, especially those intended to reduce fire blight, come with the risk of increased fruit set and reduced fruit size and return bloom.

scholarly journals Impact of Repeated Yearly Applications of Prohexadione-Calcium On Vegetative and Reproductive Growth of ‘Golden Delicious’/M.9 Apple Trees

2017 ◽  
Vol 25 (1) ◽  
pp. 47-54 ◽  
Author(s):  
A. Nilgün Atay ◽  
Fatma Koyuncu
Keyword(s):  
Fruit Quality ◽  
Vegetative Growth ◽  
Fruit Set ◽  
Negative Impact ◽  
Apple Trees ◽  
Reproductive Growth ◽  
Node Number ◽  
Golden Delicious ◽  
Vegetative And Reproductive Growth ◽  
Prohexadione Calcium

Abstract Growth retardants have great potential to balance between vegetative and reproductive growth. To assess the effects of prohexadione-calcium (Pro-Ca, Regalis) on reproductive and vegetative growth, return bloom, fruit set, and also fruit quality in ‘Golden Delicious’ apple grafted on M.9 rootstock, an experiment was performed during 2010-2012. The applications of 125 mg dm-3 Pro-Ca on the same trees in each year resulted in a 40-43% shoot length reducing. Internodes length decreased with Pro-Ca at about 30%, while total node number was unaffected. Results indicate that Pro-Ca applications have no effects on tree trunk growth, flowering, yield, fruit set and development. Pro-Ca also didn’t have any negative impact on fruit quality during the three consecutive years. Moreover, Pro-Ca resulted in higher fruit size compared to control in the third year of trial. The results of this experiment clearly suggest that fruit growers can use Pro- Ca for the control of vegetative growth without having any negative effects on fruit quality and yield parameters. Once a full canopy has been achieved, annual shoot growth can be suppressed in the range of 20 to 30 cm with 125 mg dm-3 Pro-Ca treatment in ‘Golden Delicious’ apple trees.

scholarly journals Cropping Efficiency of Young `Fuji' Apple Trees

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 886A-886
Author(s):  
Preston K. Andrews ◽  
Margaret L. Collier
Keyword(s):  
Vegetative Growth ◽  
Fruit Size ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Apple Trees ◽  
Cross Sectional ◽  
Crop Load ◽  
Previous Season ◽  
Crop Density ◽  
Fuji Apple

Effects of crop load and time of thinning on productivity of young `Fuji'/M.9 apple trees were tested by hand blossom (B) or fruit (F) thinning to two crop densities (fruit number/trunk cross-sectional area). Heavy (H) crop densities resulted in higher yields in both 2nd and 3rd leaf than light (L) crop densities. Time of thinning had no effect on yields in either year. In the 2nd leaf, fruit size was largest from trees B thinned to L crop densities, and smallest from trees F thinned to either crop density from mid-June through harvest. Both 1° and 2° vegetative growth were greatest in noncropped trees, intermediate in trees with L crops, and least in trees with H crops. Noncropped 2nd-1eaf trees had the highest flowering indices (flower clusters/100 total buds) the following spring and H cropped trees had the lowest. The flowering index was higher when trees were B thinned in the 2nd leaf than when F thinned. In the 3rd leaf, fruit size was largest when borne on weak upright shoots, intermediate on spurs, and smallest on 1-year-old terminal wood. Fruit on spurs had the highest incidence of sunscald (17%) and fruit on weak upright shoots the lowest (8%). Previous-season crop densities affected current-season's vegetative and fruit growth.

Performance of prohexadione-calcium on shoot growth and fruit quality of apple — Effect of spray surfactants

2008 ◽  
Vol 88 (1) ◽  
pp. 165-174 ◽  
Author(s):  
J. A. Cline ◽  
C. G. Embree ◽  
J. Hebb ◽  
D. S. Nichols
Keyword(s):  
Vegetative Growth ◽  
Shoot Growth ◽  
Management Practice ◽  
Fruit Size ◽  
Growth Control ◽  
Growth And Yield ◽  
Control Treatment ◽  
Royal Court ◽  
The Us ◽  
Prohexadione Calcium

Vegetative growth control of apples (Malus × domestica Borkh.) is necessary to maintain a balance between growth and cropping. Pruning is a labour-intensive management practice to achieve this and intrinsically stimulates new growth. Prohexadione-calcium (PC) is a plant bio-regulator that effectively regulat es the shoot extension growth of apples and other tree fruits. Previous research has demonstrated that its efficacy can vary based on the use of spray surfactants and adjuvants. This study investigated the efficacy of two rates of Apogee™, the commercial form of PC, used in combination with the spray surfactants Sylgard 309 and LI 700, on extension shoot growth and yield parameters. Experiments were conducted in Ontario on Empire and Nova Scotia on Royal Court™ Cortland apples. Treatments of 0, 75 or 125 mg L-1 PC, with and without either 0.5% (vol/vol.) LI 700 surfactant or 0.05% (vol/vol) Sylgard 309 surfactant were applied to Empire trees, and 75 or 125 mg L-1 PC, with or without 0.5% (vol/vol) LI 700, were applied to Royal Court™ trees. An untreated control treatment was also included for comparison purposes. A total of two sprays were applied to the Empire trees and a total of three sprays were applied to the Royal Court™ trees. PC significantly decreased the vegetative growth of Empire and Royal Court™ trees by approximately 18 to 44%, respectively, and the efficacy of PC was enhanced when combined with either Sylgard 309 or LI 700 surfactant. No additional benefit in vegetative growth control was gained when using Apogee™ at rates of 125 mg L-1 PC, relative to 75 mg L-1 PC. The rate of Apogee™ did not influence the number of fruit or yield per tree or mean fruit size of either cultivar. For Empire, LI 700 and Sylgard 309 significantly reduced the number of fruit per tree, resulting in lower yields and crop densities. In addition, higher mean fruit weights, and a greater distribution of fruit in the larger size categories were observed for LI 700. Fruit from Royal Court trees treated with the highest rate of Apogee™ had higher crop densities, poorer coloured fruit, and a higher percentage of fruit less than 60 mm in diameter. These data provide support for the use of alternative surfactants with Apogee™ other than those listed on the US and Canadian product labels. Key words: Apogee™, Empire, Cortland, Regalis, calcium 3-oxido-5-oxo-4-propionylcyclohex-3-enecarboxylate, surfactant

scholarly journals Growth and Productivity of Vigorous `Northern Spy'/MM.106 Apple Trees in Response to Annually Applied Growth Control Techniques

1990 ◽  
Vol 115 (2) ◽  
pp. 212-218 ◽  
Author(s):  
D.C. Elfving ◽  
R.A. Cline
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Growth Control ◽  
Shoot Length ◽  
Apple Trees ◽  
Bud Formation ◽  
Control Techniques ◽  
Terminal Bud ◽  
Time Required ◽  
Growth Regulator Treatment

Beginning in 1982, daminozide (DZ) was applied annually for 5 years to whole, 5-year-old `Northern Spy'/MM.106 (Malus domestics Borkh.) trees: a) shortly after bloom, b) together with ethephon (ETH) 6 to 7 weeks after bloom, or c) after harvest. Controls were unsprayed. One-half of the trees receiving each growth regulator treatment were summer-pruned after terminal-bud formation each year. Postharvest DZ reduced shoot numbers, mean shoot length, trunk enlargement, and fruit size, but had little or no effect on bloom, fruit set, or yield. Postbloom DZ, summer DZ plus ETH, and summer-pruning reduced vegetative growth and time required for dormant-pruning, but only postbloom DZ and summer DZ plus ETH increased spur density in the tree. Postbloom DZ and summer DZ plus ETH increased both flowering and cropping in 3 of the 5 years, with little effect on fruit set. Fruit size was reduced only in years when cropping was enhanced. Total yields (1982-86) were increased 34% and 36% by postbloom DZ and summer DZ plus ETH, respectively. Summer-pruning had no effect on fruit size in any year, but reduced yields in 1984 and 1986. Year-to-year fluctuation in yield was unaffected by any treatment. Growth-control treatments had no direct effect on foliar or fruit macronutrient concentrations. Chemical names used: butanedioic acid mono (2,2-dimethylhydrazide) (daminozide); 2-chloroethylphosphonic acid (ethephon).

scholarly journals Post-bloom and preharvest treatment of ‘Braeburn’ apple trees with prohexadione-calcium and GA4+7 affects vegetative growth and postharvest incidence of calcium-related physiological disorders and decay in the fruit

2020 ◽  
Vol 261 ◽  
pp. 108919 ◽  
Author(s):  
Cassandro V.T. do Amarante ◽  
João Paulo G. Silveira ◽  
Cristiano A. Steffens ◽  
Sergio T. de Freitas ◽  
Elizabeth J. Mitcham ◽  
...  
Keyword(s):  
Vegetative Growth ◽  
Apple Trees ◽  
Physiological Disorders ◽  
Prohexadione Calcium

scholarly journals Net Enclosure of ‘Honeycrisp’ and ‘Gala’ Apple Trees at Different Bloom Stages Affects Fruit Set and Alters Seed Production

Agronomy ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 478 ◽  
Author(s):  
Mokhles Elsysy ◽  
Sara Serra ◽  
Phil Schwallier ◽  
Stefano Musacchi ◽  
Todd Einhorn
Keyword(s):  
Seed Production ◽  
Fruit Set ◽  
Insect Pests ◽  
Fruit Size ◽  
Quality Attributes ◽  
Parthenocarpic Fruit ◽  
Apple Trees ◽  
Apple Production ◽  
Commercial Crop ◽  
Mature Seeds

Thinning is a critical but challenging practice in apple production, especially for organic producers. The objective of this experiment was to determine if exclusion netting, used to manage insect pests and stress, could reduce fruit set and thinning requirements of ‘Gala’ and ‘Honeycrisp’ apple trees in Michigan and Washington, U.S.A., respectively. Nets were closed around whole canopies at different timings based on a predetermined percentage of open flowers. In 2017 and 2018, netted trees set a full commercial crop regardless of percentage of open bloom at the time of netting, including prebloom enclosures. Fruit set and yield of netted ‘Honeycrisp’ trees were significantly lower than non-netted, nonthinned controls but similar to non-netted hand-thinned controls. ‘Gala’ fruit set and yield did not differ among treatments. Exclusion netting markedly reduced the number of mature seeds and increased the number of nonfertilized seeds in both cultivars. Pollinator exclusion to ‘Gala’ in a frost year increased parthenocarpic fruit set two-fold compared to non-netted trees. Fruit size, shape, and quality attributes of ‘Gala’ were were similar among treatments, but ‘Honeycrisp’ fruit were significantly smaller than hand-thinned, non-netted controls. Netting may constitute an alternative, viable strategy to manage fruit set but requires testing on different cultivars.

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 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.

scholarly journals Phenology of ‘Magallanes’ Pummelo (Citrus maxima) Trees and Its Growth and Development as Influenced by Potassium Nutrition

2019 ◽  
pp. 1-18
Author(s):  
Alminda Magbalot-Fernandez ◽  
Constancio C. De Guzman
Keyword(s):  
Fruit Development ◽  
Vegetative Growth ◽  
Fruit Set ◽  
Foliar Application ◽  
Soil Analysis ◽  
Fruit Size ◽  
Tree Height ◽  
Maximum Growth ◽  
Nutrient Competition ◽  
Citrus Maxima

This study aimed to determine the influence of potassium (K) fertilization on the vegetative growth, flowering and fruit development of 13-year old ‘Magallanes’ pummelo [Citrus maxima (Burm. Ex Rumph.) Merr.] trees. The experiment was conducted at South Davao Corporation (SODACO) farm, Davao city for 12-months duration. Five treatments were observed with increasing K levels were applied per tree: control (no fertilization), without K, 150 g K basal (recommended rate based on soil analysis), 225 g K basal, and 225 g K basal + foliar application. The critical stage of tree growth coincided with the months of May and August. Peak leaf flushing occurred in June and peak flowering with fruit set in April. The crucial stage of fruit development was noted two months after fruit set. Thus, optimum fertilization must be applied during these stages for maximum growth and production in ‘Magallanes’ pummelo. The vegetative growth of pummelo was not affected by increasing K rates. The recommended rate (150g K basal per tree) significantly increased canopy diameter by 76% but higher K rates did not increase tree height, due to the effect of fruit load and nutrient competition. On the other hand, increasing K rates to 50% higher than the recommended rate (225 g K per tree) increased the number of flushes by 36-100%. Flowering, fruit set and yield of ‘Magallanes’ pummelo were also enhanced by higher K rates. Flowering was increased by 4 times, fruit set by 86-100%, fruit number by 7 times, weight per fruit by 22-26%, and yields up to 9 times on trees composted with 225 g K rates.  The fruit size (diameter and length), however, did not increase by increasing the K level.

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