ISHS Acta Horticulturae 694: International Symposium on Harnessing the Potential of Horticulture in the Asian-Pacific Region
THE USE OF PROHEXADIONE-CA FOR IMPROVED CROP MANAGEMENT |
| Authors: | G.A. Dayatilake, J.N. Wünsche, P. Wood, S. McArtney, D. Manktelow, P. Lo, S. Gurnsey, D.S. Tustin |
| Keywords: | Vigour, fruit quality, ALCM, fireblight, powdery mildew, black spot |
| Abstract:
Prohexadione-Ca (Regalis®) is a plant growth retardant which acts through the inhibition of gibberellin biosynthesis, leading to a suppression of shoot elongation and hence modification of canopy growth. There is also evidence that it may induce resistance to pest and disease infestations. In the present study, effects of spray applications of Regalis at early shoot growth (1cm) and at 4 weekly intervals thereafter on apple shoot growth, fruit quality and pest and disease infestations were studied. Regalis treatments significantly reduced extension shoot growth, resulting in relatively open tree canopies and a decrease of immature leaf area potentially susceptible to pests and diseases. There was a clear enhancement of the coverage of surface blush and red colour intensity of fruit by Regalis treatments, suggesting better light penetration. There was no significant effect on fruit set, fruit size and export packout. Powdery mildew incidence was reduced but fireblight infection of floral clusters was not affected possibly because Regalis applications were too late in the season to have an effect. Black spot and apple leaf curling midge (ALCM) levels were too low in the orchard to determine the effectiveness of Regalis on control. | |
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