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John Warner

`Sturdeespur Delicious', `MacSpur`, `Summerland McIntosh', `Idared', and `Empire' apple trees (Malus domestics Borkh.) planted in 1986 on various size-controlling rootstock were used to determine the effect of rootstock on primary scaffold branch crotch angle. There were differences in crotch angle depending on rootstock. Rootstock effects were more pronounced with the upright growing `Sturdeespur Delicious' than with `Idared' and `Empire', which have a spreading growth habit. Ottawa 8 rootstock had a tendency to produce primary branches with wider crotch angles than other semidwarf to standard rootstock.

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James R. Schupp, H. Edwin Winzeler, and Melanie A. Schupp

retained and the attendant axillary buds allow release from apical dominance, resulting in localized stimulation of branching. Stubbing is a type of heading cut whereby only a small section of a 2-year-old or older limb is retained to limit the potential

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Roar Moe, John E Erwin, and Will Carlson

The role of irradiance and/or ethylene in inducing mortality and self-branching disorders in Gerbera jamesonii Bolus. seedlings was studied. Seedling mortality increased from 8% to 57% when seed was covered with vermiculite than left uncovered during germination. Supplemental lighting for 30 days after germination decreased seedling mortality and decreased the time to visible bud compared to seed germinated under natural light only. In subsequent experiments, seeds were germinated and then seedlings were water logged or sprayed with ethephon (0.69, 3.45, or 17.25 mM) at four different stages of seedling development. Half of the ethephon-treated seedlings were sprayed with silver thiosulfate (STS). Seedling mortality was greatest after cotyledon expansion but before expansion of the first tree leaf. The highest ethephon concentration caused reduced seedling dry weight after 42 days. Applying STS did not overcome self-branching or meristem necrosis.

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Don C. Elfving and Dwayne B. Visser

A new bioregulator, cyclanilide (CYC, Bayer Environmental Science, Research Triangle Park, NC 27709), was compared with a proprietary formulation of 6-benzyladenine and gibberellins A4 and A7 [Promalin (PR), Valent BioSciences, Walnut Creek, Calif.] for branching effects on sweet cherry trees. CYC stimulated the formation of lateral shoots on current-season's shoot growth under both orchard and nursery conditions. In the nursery CYC was as effective or better for feathering compared to PR in all cherry cultivars tested. There were no synergistic effects of CYC/PR tank mixes on feather development. Crotch angles of induced feathers were not different from the angles of feathers that formed spontaneously. The growth of CYC-induced feathers was sufficient to produce acceptable quality feathered trees. Trunk caliper of nursery trees was either not affected or reduced to a very minimal degree. CYC is effective for lateral branch induction in sweet cherry, especially in the nursery. Chemical names used: 1-(2,4-dichlorophenylaminocarbonyl)-cyclopropane carboxylic acid (cyclanilide); N-(phenylmethyl)-1H-purine-6-amine + gibberellins A4 and A7 (Promalin); polyoxyethylenepolypropoxypropanol, dihydroxypropane, 2-butoxyethanol (Regulaid).

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Duane W. Greene and Wesley R. Autio

Apple trees (Malus domestica Borkh.) were notched with a hacksaw blade by removing a 2-mm-wide strip of bark from directly above a bud. The cut extended down to the secondary xylem and around about one-third of the circumference of the stem. The most effective time to notch was ≈2 to 4 weeks before full bloom. Notching was most effective at inducing shoot growth from buds on the top of a branch, less effective for buds on the side, and least effective for buds on the underside of a branch. On untreated controls, the most shoots grew from the upper one-third of 1- or 2-year-old growth, and very few shoots developed buds on the lower one-third. If a bud was notched, however, the pattern was similar and incidence of shoot development was high. The percentage of notched buds that developed into shoots was not influenced by wood age.There was a positive, linear relationship between bud size and the percentage of buds growing into lateral shoots and between bud size and the length of those lateral shoots. Over all years, experiments, and cultivars, notching increased shoot production ≈600%.

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Gary J. Keever

Eight species of container-grown woody landscape plants received a single foliar spray of 0, 25, 50, 100, or 200 mg a.i. ASC-66952 ·liter-1 on 13 June 1990. (ASC-66952 is a proprietary chemical being developed by ISK-Biotech.) Axillary, rhizomatous, and total shoot numbers of `Harbour Dwarf' nandina were increased with increasing concentrations of ASC-66952. Relative to those of the control plants, axillary shoot numbers were increased from 350% with 25 mg·liter-1 to 950% with 200 mg·liter-1, while rhizomatous shoot numbers were increased 144% with the lowest concentration and 477% with the highest concentration. Growth indices were decreased from 2.1% with 25 mg·liter-1 to 9.7% with 200 mg·liter-1. Branching and growth indices of other species tested were minimally affected by ASC-66952 application.

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Charlotte M. Guimond, Preston K. Andrews, and Gregory A. Lang

Young sweet cherry (Prunus avium) trees are typically upright, vegetatively vigorous, and nonprecocious, taking 5 to 6 years to come into production. To produce fruit in high-density orchards by year 3 or 4, development of lateral shoots for potential fruiting is critical in year 2 or 3. An experiment was designed to promote lateral branching on 2-year-old trees. The experiment was conducted in a commercial orchard in Roosevelt, Wash., with `Bing' and `Van' on the vigorous rootstocks Mazzard and Colt. The trees were planted at 415 trees per acre with three scaffolds trained into a “V” canopy design. The experimental variables were treatments with and without Promalin (1.8% BAP plus 1.8% GA4+7), applied at a ratio of 1:3 in latex paint at green tip stage; superimposed on these treatments were either heading cuts of each scaffold to 2 m long (or tipping the scaffold if it was <2 m), removing four to five buds subtending the terminal bud, a combination of heading and bud removal, or controls. On trees that were not treated with Promalin, three additional treatments included either removing subtending buds at budbreak, or removing buds at multiple locations along the scaffold at green tip or at budbreak. New lateral shoots were counted 4 weeks after budbreak, and the quality of the shoots (shoot diameter and angle of emergence) was measured at the time of summer pruning. Interactions between Promalin, bud manipulation, and pruning will be discussed in relation to development of canopy structure.

Open access

Wei Hai Yang, Chao Zhong Lu, Wei Chen, and Huan Yu Xu

; Li et al., 2015 ). Girdling, defined as the removal of a ring of bark around the branches or trunk, is an important technique and has been widely used to improve fruit retention and increase fruit yield ( Annabi et al., 2019 ; Goren et al., 2003

Open access

Nihad Alsmairat, Philip Engelgau, and Randolph Beaudry

instance, is consumed in the synthesis of several amino acids including lysine, methionine, and threonine, the latter of which is a precursor to isoleucine ( Azevedo et al., 1997 ). Branched-chain (BC) esters are important contributors to the fruity aroma

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S.A. Oosthuyse, G. Jacobs, and D.K. Strydom

Upright l-year-old apple (Malus domestica Borkh. `Granny Smith') branches were headed at 14-day intervals (branches headed once each) during late winter and in spring [70 days before full-bloom (DBFB) until 28 days after full-bloom (DAFB)] and budbreak and new shoot growth quantified on the remaining branch section after cessation of these events. When heading was performed 70, 56, or 42 DBFB, four to five buds broke on average. When branches were headed subsequently, the average number of buds breaking increased progressively, then decreased with heading date, the maximum number breaking (13) on branches headed 14 DAFB. An average of 10 or 11 buds broke per branch section when heading was performed 28 DAFB. In late summer, the total length of new shoots per branch section for the branches headed before full bloom averaged 113 cm, whereas that on the branches headed at or after full-bloom averaged 76 cm.