Blossom Thinning in Apple and Peach with an Essential Oil

Miller, Stephen; Tworkoski, Thomas

doi:10.21273/hortsci.45.8.1218

Cited by 17 publications

(12 citation statements)

References 23 publications

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“…Crop loads on hand-thinned and mechanically thinned trees in this study and in a previously published report (Schupp et al, 2008) were generally approximately five fruit/cm 2 limb or trunk cross-sectional area or below. Observations (S. Miller, unpublished data) and reports (Miller and Tworkoski, 2010) indicate that crop load densities below five fruit/cm 2 in peach are associated with the larger size (%7.6 cm) fruits preferred by consumers.…”

Section: Resultsmentioning

confidence: 93%

Performance of Mechanical Thinners for Bloom or Green Fruit Thinning in Peaches

Miller¹,

Schupp²,

Baugher³

et al. 2011

horts

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Peach (Prunus persica L. Batsch) thinning is a costly and time-consuming but necessary practice to produce a crop of marketable size fruit. A number of mechanical devices and methods have been developed and evaluated to reduce the cost and time required for hand thinning peach. This report provides additional evidence that a Darwin string thinner can effectively thin peach at bloom and a spiked drum shaker can thin at bloom or at the green fruit (pit hardening) stage. Five trials were conducted over 2 years in grower orchards with trees trained to a perpendicular V system. A Darwin string thinner at 60% to 80% full bloom (FB) reduced crop load (fruit/cm2 limb cross-sectional area) on scaffold limbs by 21% to 50% compared with a hand-thinned control. At the 60% FB stage, a USDA-designed double-spiked drum shaker reduced crop load by 27% and in another trial, a USDA prototype single-drum shaker reduced crop load by 9%. Across all trials, the spiked drum shakers (single or double units) removed an average of 37% of the green fruit. All mechanical devices reduced the time required for follow-up hand thinning. Follow-up hand-thinning costs (US$/ha) were reduced an average of 27% by mechanical thinning devices over hand-thinned control trees. Fruit size was increased over hand-thinned controls by mechanical thinning in most, but not all, trials. A combined treatment of the Darwin string thinner at bloom followed by a drum shaker (single or double unit) at the green fruit stage produced the greatest net economic impact in a number of the trials. Despite overthinning in some trials, the mechanical thinning devices described provide a potential alternative to hand thinning alone in peach production.

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Section: Resultsmentioning

confidence: 93%

Performance of Mechanical Thinners for Bloom or Green Fruit Thinning in Peaches

Miller¹,

Schupp²,

Baugher³

et al. 2011

horts

Self Cite

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“…The application of EOs in apple tree may lead to phytotoxicity depending on the application method, concentration, and adaptive duration. For example, 7% of flowers were injured for clove oil in a thinning experiment for concentrations as low as 2% ( Miller and Tworkoski, 2010 ). Fruit damages were also reported in postharvest treatment with savory, oregano, and thyme EOs at concentrations of 1–10% for the purpose of controlling Botrytis cinerea and Penicillium expansum ( Lopez-Reyes et al, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

Biopesticide Trunk Injection Into Apple Trees: A Proof of Concept for the Systemic Movement of Mint and Cinnamon Essential Oils

et al. 2021

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The use of conventional pesticides is debated because of their multiple potential adverse effects on non-target organisms, human health, pest resistance development and environmental contaminations. In this setting, this study focused on developing alternatives, such as trunk-injected essential oil (EO)-based biopesticides. We analysed the ecophysiology of apple trees (Malus domestica) following the injection of Cinnamomum cassia and Mentha spicata nanoemulsions in the tree’s vascular system. Targeted and untargeted volatile organic compounds (VOCs) analyses were performed on leaf-contained and leaf-emitted VOCs and analysed through dynamic headspace–gas chromatography–mass spectrometry (DHS-GC-MS) and thermal desorption unit (TDU)-GC-MS. Our results showed that carvone, as a major constituent of the M. spicata EO, was contained in the leaves (mean concentrations ranging from 3.39 to 19.7 ng gDW–1) and emitted at a constant rate of approximately 0.2 ng gDW–1 h–1. Trans-cinnamaldehyde, C. cassia’s major component, accumulated in the leaves (mean concentrations of 83.46 and 350.54 ng gDW–1) without being emitted. Furthermore, our results highlighted the increase in various VOCs following EO injection, both in terms of leaf-contained VOCs, such as methyl salicylate, and in terms of leaf-emitted VOCs, such as caryophyllene. Principal component analysis (PCA) highlighted differences in terms of VOC profiles. In addition, an analysis of similarity (ANOSIM) and permutational multivariate analysis of variance (PERMANOVA) revealed that the VOC profiles were significantly impacted by the treatment. Maximum yields of photosystem II (Fv/Fm) were within the range of 0.80–0.85, indicating that the trees remained healthy throughout the experiment. Our targeted analysis demonstrated the systemic translocation of EOs through the plant’s vascular system. The untargeted analysis, on the other hand, highlighted the potential systemic acquired resistance (SAR) induction by these EOs. Lastly, C. cassia and M. spicata EOs did not appear phytotoxic to the treated trees, as demonstrated through chlorophyll fluorescence measurements. Hence, this work can be seen as a proof of concept for the use of trunk-injected EOs given the systemic translocation, increased production and release of biogenic VOCs (BVOCs) and absence of phytotoxicity. Further works should focus on the ecological impact of such treatments in orchards, as well as apple quality and production yields.

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“…Fruit thinning at the appropriate time allows the remaining fruit to develop to its maximum size. Thinning at bloom time often results in larger fruits at harvest, whereas thinning fruits too late reduces the chances that fruit size will increase (Miller and Tworkoski, 2010 ). Here, ALA application at 50–75% bloom effectively thinned fruits.…”

Section: Discussionmentioning

confidence: 99%

5-Aminolevulinic Acid Thins Pear Fruits by Inhibiting Pollen Tube Growth via Ca2+-ATPase-Mediated Ca2+ Efflux

Duan

et al. 2016

Front. Plant Sci.

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Chemical fruit thinning has become a popular practice in modern fruit orchards for achieving high quality fruits, reducing costs of hand thinning and promoting return bloom. However, most of the suggested chemical thinners are often concerned for their detrimental effects and environmental problems. 5-Aminolevulic acid (ALA) is a natural, nontoxic, biodegradable, and environment-friendly plant growth regulator. One of its outstanding roles is improving plant photosynthesis and fruit quality. Here, results showed that applying 100–200 mg/L ALA at full bloom stage significantly reduced pear fruit set. Both in vivo and in vitro studies showed that ALA significantly inhibited pollen germination and tube growth. ALA decreased not only cytosolic Ca2+ concentration ([Ca2+]cyt) but also “tip-focused” [Ca2+]cyt gradient, indicating that ALA inhibited pollen tube growth by down-regulating calcium signaling. ALA drastically enhanced pollen Ca2+-ATPase activity, suggesting that ALA-induced decrease of calcium signaling probably resulted from activating calcium pump. The significant negative correlations between Ca2+-ATPase activity and pollen germination or pollen tube length further demonstrated the critical role of calcium pump in ALA's negative effect on pollen germination. Taken together, our results suggest that ALA at low concentrations is a potential biochemical thinner, and it inhibits pollen germination and tube growth via Ca2+ efflux by activating Ca2+-ATPase, thereby thinning fruits by preventing fertilization.

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Blossom Thinning in Apple and Peach with an Essential Oil

Cited by 17 publications

References 23 publications

Performance of Mechanical Thinners for Bloom or Green Fruit Thinning in Peaches

Performance of Mechanical Thinners for Bloom or Green Fruit Thinning in Peaches

Biopesticide Trunk Injection Into Apple Trees: A Proof of Concept for the Systemic Movement of Mint and Cinnamon Essential Oils

5-Aminolevulinic Acid Thins Pear Fruits by Inhibiting Pollen Tube Growth via Ca2+-ATPase-Mediated Ca2+ Efflux

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