Gibberellic Acid Sprays

Gibberellic acid (GA) is a naturally occurring compound in a group of plant hormones called gib-berellins. GA application to table grape clusters may produce several responses. When it is applied to clusters early in their development, it may lengthen the cluster stem (rachis) to reduce cluster compactness. However, this response to GA application is often negated by the natural elongation of the cluster in a later stage of cluster development. Therefore, there is seldom a true cluster-loosening benefit from such early-season GA sprays. Efforts to use GA for this purpose should be evaluated carefully before it is adopted as a standard practice.

Seeds cause an increase in the size of grape berries by producing growth-stimulating hormones including gibberellins. Therefore, seedless grape berries are typically small in their natural condition. GA sprays often dramatically increase the size of seedless grape berries, presumably because they partially substitute for the natural production of gibberellins from seeds.

A spray of GA at midbloom not only may increase berry size but in some varieties can also reduce the number of berries that set per cluster. However, the optimum time for a single application of GA to increase berry size is often at fruit set, when the berries are 4 to 5 mm in diameter (Fig. 22). Commercial applications of GA to increase berry size often involve two or more applications after fruit set, but most of the berry-sizing benefit is obtained by a single application. Trial applications of GA to seedless varieties without a history of GA use should be timed at fruit set (Fig. 22). A concentration of 50 ppm is often effective, but only 25 ppm should be used on 'Vanessa' and as little as 5 ppm is considered optimum for some varieties. Growers will often greatly benefit from the use of GA on many seedless table grape varieties, including 'Himrod', 'Lakemont', 'Vanessa', 'Glenora' and 'Reliance'. Avoid GA use on 'Canadice', 'Mars' and 'Marquis'. Consult the product label for details of application. Sources of GA are listed in Appendix B.

GA applications may also have negative effects on grapevines, including excessive reduction of the number of berries per cluster, the production of grassy or herbaceous flavors in the fruit, a reduction in tissue winter hardiness and a reduction in node fruitfulness. These phytotoxic effects of GA tend to become more pronounced as the seeded condition of the berry increases. Therefore, avoid GA sprays on seeded table grape varieties. Gibberellic acid solutions have been successfully applied to some seeded table grape varieties as a cluster dip. For example, there is significant commercial production of seedless Delaware grapes in Japan. They are produced by individually dipping clusters in a GA solution at bloom. Trials of GA on seeded table grape varieties are more likely to be successful as a cluster dip rather than as a spray.

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  • rhian
    What are the advantages of using GA on table grape production?
    7 years ago
    When to apply gibberellic acid to grape clusters?
    6 years ago
  • Katja
    How much ppm gibberillic acid for seedless grape growth?
    6 years ago
  • Baldassarre
    How to use gibberellic acid on grapes?
    4 years ago
  • Pinja Sademies
    When can you spray giberellic acid?
    4 years ago
  • massawa
    How do you apply gibberalic acid to table grapes?
    4 years ago
  • deodato
    Which product is good in grape dipping with gibberellic acid?
    2 years ago
  • Maunu
    How do you apply gibberellic acid to grapes?
    2 years ago
  • christopher coley
    Which hormone used for seedless grape?
    1 year ago
  • zuzanna
    What is ppm in grapes farming?
    1 year ago
  • amanuel
    How to use gibberellic acid on victoria grape?
    12 months ago
  • kieran
    When appli ga3 on grape?
    11 months ago
  • Noemi
    Which hormon increase size of grap bunch?
    11 months ago
    Which hormone used increase the no and size of grape in bunch?
    11 months ago
    How to ga3 application on grape?
    9 months ago
  • Aatifa Nebay
    How prepare gibralic acid solution in grape?
    9 months ago
  • Yusuf
    What is berry set on grapes?
    8 months ago
  • sirja
    Does bronco wine use gebrillic acid on their grapes?
    7 months ago
  • Thorsten
    How to use Gibberellic Acid (GA3) for grapes?
    5 months ago
  • manu laaksonen
    Is it good to spray gobberllic acid spray on watermelon?
    2 months ago
  • sinit temesgen
    How much gibberellic aid in water for grapes?
    2 months ago
  • mark
    How does gibberellin cause seedless grapes?
    29 days ago

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