‘D’Anjou’ Pear Shoot Growth and Return Bloom, but Not Fruit Size, Are Reduced by Prohexadione-Calcium

Prohexadione-calcium (P-Ca) was applied to ‘Anjou’ pear (Pyrus communis L.) trees in the lower and upper Hood River Valley (HRV), Oregon, to determine its effectiveness for managing the excessive vigor of ‘Anjou’ under different growing climates. Vegetative growth and development (weekly shoot growth rate, total annual extension growth, number of initiated shoots, internodal length, and number of nodes), yield (fruit number and fruit size), and return bloom dynamics were evaluated between 2010 and 2013. P-Ca consistently reduced shoot elongation by ≈40% in all years and at both sites when doses of 250 ppm were applied in early spring (i.e., ≈5 cm of annual shoot extension) compared with untreated trees. Shorter shoots were the result of both reduced internodal growth and fewer nodes. In the cooler, upper HRV, a single P-Ca application controlled shoot elongation for the entire season, but in the warmer, lower HRV, a second flush of growth was generally observed ≈60 days after the first application. A subsequent P-Ca application (250 ppm) provided added growth control in some instances. Yield was unaffected by P-Ca the season of application; however, in one year, an increase in fruit number indirectly led to reduced fruit size; otherwise, fruit size was unaffected by P-Ca. Postharvest fruit quality was not influenced substantially by P-Ca. Return bloom, however, was consistently reduced by P-Ca. Return yield, the year after P-Ca application (recorded in 2013 only), was reduced in proportion to the decrease in return bloom relative to untreated trees. In 2012, ethephon was also evaluated, alone or in combination with P-Ca. When applied on its own either once (150 ppm, 5-cm growth), or twice [150 ppm, 5-cm growth; 300 ppm, 57 days after full bloom (DAFB)], ethephon did not affect vegetative growth or yield components but did improve return bloom and return yield relative to other treatments; however, when combined with P-Ca, ethephon did not reverse reductions in return bloom or return yield induced by P-Ca. The most effective ethephon treatment for promoting flowering and return yield (300 ppm, 57 DAFB) was not tested in combination with P-Ca. We conclude that P-Ca is an effective tool for controlling vigor of ‘Anjou’ trees, but the decrease in return bloom requires additional investigation. Further work testing combinations of ethephon and P-Ca are warranted to optimize growth and productivity of ‘Anjou’ trees.

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

Canadian Journal of Plant Science ◽

10.4141/cjps07087 ◽

2008 ◽

Vol 88 (1) ◽

pp. 165-174 ◽

Cited By ~ 12

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

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Prohexadione calcium on shoot growth of 'Starkrimson' pear trees

Pesquisa Agropecuária Brasileira ◽

10.1590/s0100-204x2017000200001 ◽

2017 ◽

Vol 52 (2) ◽

pp. 75-83 ◽

Cited By ~ 2

Author(s):

Mateus da Silveira Pasa ◽

Todd Einhorn

Keyword(s):

Vegetative Growth ◽

Shoot Growth ◽

Block Design ◽

Fruit Size ◽

Internode Length ◽

Soluble Solids ◽

Cross Sectional ◽

Growing Seasons ◽

Return Bloom ◽

Prohexadione Calcium

Abstract: The objective of this work was to evaluate the fruiting and vegetative growth of 'Starkrimson' pear in response to the application of prohexadione calcium (P-Ca). P-Ca (250 mg L-1) was sprayed to scaffold limbs and to whole trees in commercial orchards. A randomized complete block design was used to minimize declivity effects. Vegetative growth (length and number of shoots, increment in limb and trunk cross-sectional area, number of nodes, and internode length), production (fruit number, yield, yield efficiency, and fruit size), and return bloom were evaluated from 2010 to 2013. P-Ca efficiently controlled shoot growth in all growing seasons, when applied early in the season, due to the reduction in internode length. Production was not negatively affected by the application of P-Ca in all years and at both sites, and fruit size and return bloom were not reduced. Fruit quality attributes were also little affected by P-Ca, except for total soluble solids content, which was lower than that of the control. This shows that P-Ca is efficient to manage tree vigor in high-density 'Starkrimson' pear orchards.

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

HortScience ◽

10.21273/hortsci.43.2.376 ◽

2008 ◽

Vol 43 (2) ◽

pp. 376-379 ◽

Cited By ~ 15

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.

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Effects of Prohexadione-Calcium on Fruit Size and Return Bloom in Pear

HortScience ◽

10.21273/hortsci.39.6.1305 ◽

2004 ◽

Vol 39 (6) ◽

pp. 1305-1308 ◽

Cited By ~ 8

Author(s):

David Sugar ◽

Don C. Elfving ◽

Eugene A. Mielke

Keyword(s):

Shoot Growth ◽

Fruit Size ◽

Fruit Weight ◽

Single Application ◽

Pear Fruit ◽

Crop Load ◽

Return Bloom ◽

Old Trees ◽

Prohexadione Calcium

The effects of prohexadione-calcium (P-Ca) on fruit size and return bloom in three pear cultivars were evaluated in Medford and Hood River, Ore., and in Cashmere, Wash. A variety of treatment dosages and timings was applied to 4- and 5-year-old trees in 2 years of study. Fruit weight of `Bosc' and `Red Anjou' pears was not affected by P-Ca treatments at any location in either year. However, decreased weight of `Bartlett' pear fruit was associated with all P-Ca treatments in 1999 in Medford except for 83 ppm applied at 2.5 to 6.0 cm shoot growth (first treatment) plus 2, 4, 6, and 8 weeks after first treatment (WAFT) and 125 ppm applied at 2.5 to 6.0 cm growth plus 4 WAFT. `Bartlett' fruit weight was reduced in Medford in 2000 by all treatments except 125 ppm applied at 2.5 to 6.0 cm growth plus 4, 8, and 12 WAFT. In Cashmere in 2000, mean weight of `Bartlett' and `d'Anjou' fruit was reduced by treatments with 83 or 125 ppm applied at 2.5 to 6.0 cm growth plus 2, 4, and 6 WAFT and of `Bosc' pear by all treatments that included more than a single application of P-Ca. Crop load was not significantly different among treatments at any location. Return bloom in the year following P-Ca treatment was reduced in `Bosc' pears by some to most treatments at all locations in both years. In contrast, return bloom was reduced in `Bartlett' and `Anjou' pears only in Hood River in 1999.

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225 Prohexadione-Ca: Reduction in Vegetative Growth and Pruning of Apple Trees

HortScience ◽

10.21273/hortsci.34.3.481a ◽

1999 ◽

Vol 34 (3) ◽

pp. 481A-481 ◽

Cited By ~ 1

Author(s):

J.R. Evans ◽

J.A. Balles ◽

B.A. Brinkman ◽

V.E. Harris ◽

J.D. Helm ◽

...

Keyword(s):

Vegetative Growth ◽

Shoot Growth ◽

Shoot Elongation ◽

Application Rate ◽

Growth Reduction ◽

Apple Trees ◽

Positive Effects ◽

Enhanced Resistance ◽

Prohexadione Calcium ◽

Made In

Prohexadione-Ca (BAS 12511W or Apogee™ Plant Growth Regulator) acts within a plant by blocking the biosynthesis of growth-active gibberellin. The result is decreased cell and shoot elongation; thus, vegetative growth in apple trees can be reduced. Air blast applications of prohexadione calcium were made in the Spring 1998 in commercial orchards. Application rate was 125 ppm a.i. applied twice beginning at 5 to 12 cm of new shoot growth. Reduction of shoot growth averaged 45% across locations. As a result of reduced vegetative growth, dormant pruning was reduced. In total, significant benefits to the grower included reduced pruning costs in addition to other positive effects such as improved light penetration and enhanced resistance to some pathogens. Research will continue with the effect of prohexadione-Ca on pruning in multiple year studies.

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163 The Influence of Apogee and Its Combination with Ethephon, Chemical Thinners, Cations, and/or Adjuvants for Apple Tree Growth Control and Return Bloom

HortScience ◽

10.21273/hortsci.35.3.418b ◽

2000 ◽

Vol 35 (3) ◽

pp. 418B-418

Author(s):

R.E. Byers ◽

D.H. Carbaugh ◽

L.D. Combs

Keyword(s):

Tree Growth ◽

Shoot Growth ◽

Fruit Set ◽

Growth Control ◽

Good Control ◽

Hard Water ◽

Growth Suppression ◽

Soluble Solids ◽

Return Bloom ◽

Prohexadione Calcium

Prohexadione calcium applied as a series of three applications starting soon after petal fall to `Fuji'/M.9 apple trees reduced the number of pruning cuts, pruning time, pruning weight per tree, current season's shoot length, individual shoot weights, and increased number of nodes on the lower 40 cm of shoots. Fruit diameter, soluble solids, starch, or individual fruit weights were not affected by Apogee sprays. Fruit color and firmness were slightly increased in only one experiment. Growth suppression appeared to be greater on trees cropping more heavily. When trees were more heavily thinned, less shoot growth control was achieved. Apogee applied at 250 mg/L in three applications caused a significant increase in fruit set when compared to the control. Alone Vydate, Carbaryl+Oil, or Carbary+Accel+Oil caused fruit thinning, but neither ethephon nor shading 3 days caused significant thinning. Apogee did not influence results of chemical thinners when applied between the first and second Apogee applications. The 10% and the 27.5% Apogee formulations gave similar shoot growth inhibition when applied with Regulaid or Oil+Silwet L-77. When using hard water (well water), the 27.5% Apogee formulation was not as effective as the 10% formulation. The 10% Apogee formulation has more NH4SO4 than the 27.5% formulation w/w; NH4SO4 is used to prevent inactivation of Apogee by calcium and other cations when hard water is used for spraying. The addition of CaCl (frequently used to reduce bitter pit and corkspot disorders) to the 27.5% Apogee formulation caused poorer growth control than with hard water alone. When Apogee was used at 125 mg/L, the addition of NH4SO4 restored the effectiveness of the hard water+CaCl mixture. Alone the additives NH4SO4, Ca Cl, Regulaid, and/or Oil plus L-77, had no effect on tree growth. Apogee plus L-77+Oil provided additional growth suppression when compared to Apogee+Regulaid. In 1998, three applications of Apogee (63 mg/L) or ethephon (135 mg/L) did not affected shoot growth of `Fuji'/M.9 trees at these low rates. Combinations of Apogee and ethephon gave good control of tree growth. Flowering and fruit set were not promoted by any of these applications.

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Shoot growth control of pear trees (Pyrus communis L.) with prohexadione-calcium

Scientia Horticulturae ◽

10.1016/j.scienta.2005.05.003 ◽

2005 ◽

Vol 106 (4) ◽

pp. 515-529 ◽

Cited By ~ 17

Author(s):

M. Smit ◽

J.J. Meintjes ◽

G. Jacobs ◽

P.J.C. Stassen ◽

K.I. Theron

Keyword(s):

Shoot Growth ◽

Growth Control ◽

Pyrus Communis ◽

Pyrus Communis L ◽

Pear Trees ◽

Prohexadione Calcium

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

HortScience ◽

10.21273/hortsci.42.6.1361 ◽

2007 ◽

Vol 42 (6) ◽

pp. 1361-1365 ◽

Cited By ~ 8

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.

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Effect of Water Conditioners and Surfactants on Vegetative Growth Control and Fruit Cracking of `Empire' Apple Caused by Prohexadione-calcium

HortScience ◽

10.21273/hortsci.38.6.1205 ◽

2003 ◽

Vol 38 (6) ◽

pp. 1205-1209 ◽

Cited By ~ 4

Author(s):

J.R. Schupp ◽

T.L. Robinson ◽

W.P. Cowgill ◽

J.M. Compton

Keyword(s):

New York ◽

Fruit Size ◽

Growth Control ◽

Hard Water ◽

Growth Reduction ◽

Fruit Cracking ◽

Fruit Damage ◽

Postharvest Rot ◽

Prohexadione Calcium ◽

Effective Water

Three experiments were conducted on `Empire' apple (Malus ×domestica Borkh.) to evaluate the effects of hard water, calcium chloride (CaCl2), water conditioners, surfactants, and captan fungicide on the growth reduction and fruit cracking caused by prohexadione-calcium (PC). Two applications of 63 mg·L-1 PC provided season-long growth control in two studies. Adding a water conditioner to PC reduced shoot growth more than an application of PC in hard or soft water in one New York study. Ammonium sulfate (AMS) and Choice were equally effective water conditioners. PC provided no growth control of water sprouts and had no effect on fruit set or yield. PC applied at 250 mg·L-1 reduced fruit size. `Empire' fruit cracking and corking was severe, despite the use of only 63 mg·L-1 PC in two of the three experiments. This damage was exacerbated by the addition of a water conditioner, however AMS applied with a surfactant but without PC had little or no effect on either the severity or extent of fruit injury. In a third experiment, the addition of surfactants, CaCl2, or captan to 250 mg·L-1 PC plus a water conditioner had no effect on the severity of fruit damage. Fruit cracking caused by PC increased preharvest drop in two of three experiments, and increased postharvest rot in the Geneva, N.Y., experiment where fruit were stored prior to grading. Application of PC plus a water conditioner reduced estimated gross return per hectare for `Empire. We conclude that the fruit injury is caused by the formulated PC product itself under certain environmental conditions, and that this product should not be used on `Empire. Chemical name used: calcium 3-oxido-4-proprionyl-5-oxo-3-cyclohexine-carboxylate [prohexadione-calcium (PC)].

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Controlling Floral Initiation and Vegetative Growth of Apple with Prohexadione Calcium (BAS-125W), an Experimental GA-biosynthesis Inhibitor

HortScience ◽

10.21273/hortsci.32.3.557e ◽

1997 ◽

Vol 32 (3) ◽

pp. 557E-558 ◽

Cited By ~ 1

Author(s):

Christopher L. Owens ◽

Eddie W. Stover

Keyword(s):

Vegetative Growth ◽

Shoot Growth ◽

Tree Size ◽

Floral Initiation ◽

Biosynthesis Inhibitor ◽

Nursery Stock ◽

Bud Set ◽

Terminal Bud ◽

Prohexadione Calcium ◽

Ga Biosynthesis

Early fruit production and control of tree size are important factors in the economic viability of high-density apple orchards. A horticultural tool permitting growers to induce terminal budset should provide greater control over the balance between vegetative growth and reproduction, increasing orchard production and profitability. With this goal, the experimental GA-biosynthesis inhibitor, BAS-125W, is being evaluated for effects on enhancing floral initiation and controlling tree size in young orchards. In nursery stock, the effect of inducing earlier terminal budset is also being studied for influence on storage carbohydrates and performance after planting. Studies in 1996 showed that 250 ppm BAS-125W induced terminal bud set on actively growing second-leaf `Macoun', `Delicious', and `Fuji' trees. Seven application dates from 17 June to 9 Sept. were compared to determine how time of treatment would effect degree and distribution of flowering the following year. Terminal budset typically occurred 2 weeks after application, with shoot growth resuming in 4 to 5 weeks. At two dates, treatment of growing tips only was compared with entire tree application to distinguish the direct effect of GA-inhibition on floral initiation from the effect of redistributing photosynthate. Treatment from 17 June to 29 July significantly reduced total annual shoot growth compared to the untreated controls, while later treatments had no significant effect on shoot length. Treatments of nursery stock with BAS-125W on 1 Sept. accelerated terminal bud set by at least 7 days compared to untreated controls of both `Fuji' and `Golden Delicious'. Effects of treatments on flowering and tree growth in 1997 will be discussed.

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