Direct and apparent residual effects of prohexadione - calcium applied to young cropping sweet cherry trees

Abstract

The same young cropping 'Regina' sweet cherry trees were foliar treated with prohexadione-calcium (Pro- Ca) in two consecutive years at a concentration of [ 125, 125 x 2, 250 ]-(A) and [ 250, 375, 500 ]-(B) mg ProCa l^-1, respectively. The following year some trees from A-treatments were left untreated to observe carry-over effects (C). None of A-treatments influenced tree trunk, shoot extension and internode growth, whereas B-treatments reduced shoot extension and internode length, simultaneously increasing flower bud density, particularly by 500 mg ProCa l^-1. There were no carry-over effects produced by C-trees, except some retardation in shoot extension. None of the treatments influenced the tree cropping level. Fruit diameter was reduced by A-treatments, but fruit shape (L/D ratio) and mass were reduced by treatments B, and such reduction was also exhibited by C-trees (residual effects)

Prohexadione-Ca and Ethephon Suppress Shoot Growth of Sweet Cherries (P. Avium)

“…This study indicates that under Southern Ontario climatic conditions, P-Ca can markedly decrease the vegetative shoot growth of sweet cherry trees on rootstocks that promote medium-high to high vigor. This is consistent with the results of past experiments conducted in Summerland, BC (Guak et al 2005), Poland (Jacyna and Lipa 2010;Jacyna et al 2012), Chile (Cares et al 2014), and the Pacific Northwest region of the USA (Elfving et al 2003(Elfving et al , 2004(Elfving et al , 2005.…”

“…Limiting vegetative growth of extension shoots using combination sprays of P-Ca and ETH or P-Ca alone, which resulted in a 20%-50% reduction in shoot length, is unlikely to interfere with the desired balance of vegetative and fruiting required during the transition years. Prohexidione-calcium reduces shoot internode length without affecting the number of leaves per shoot (Jacyna and Lipa 2010;Evans et al 1997), and therefore it is unlikely to negatively influence the leaf area to fruit ratio, which markedly influences fruit size (Proebsting 1990). In experiment 2 in which growth of the primary (central) leader was inhibited greater than the extension shoots (by as much as ∼80%), selective spraying of the extension shoots only while avoiding treatment of the primary leader would be preferable during the establishment phase until the tree has reached its desired height.…”

“…Prohexadione-calcium (P-Ca; trade name Apogee®, BASF Canada Inc., Mississauga, ON) is a GA synthesis inhibitor that has also been used to control excessive vegetative growth in fruit trees, notably apple (Byers et al 2004;Cline 2005;Duyvelshoff and Cline 2013), pear (Sugar et al 2004;Einhorn et al 2014), and sweet cherry (Guak et al 2005;Jacyna and Lipa 2010). Results from these studies indicate that the efficacy of P-Ca in reducing shoot elongation varies according to several factors, including climatic conditions, application timing, rate, and frequency, as well as crop and cultivar response.…”

Influence of Growth Retardants on Vegetative Growth of Apple (Malus × domestica Borkh.) Cultivars under High Density Planting System

“…Similar results have been confirmed by Basak [8] in Jonagold apple trees and Miller [9] in Red Chief Delicious apple trees. Jacyna and Lipa [10] also found that application of prohexadione-calcium resulted in reduction of internode length, total growth per branch unit and shoot extension growth in apple and sweet cherry trees. Our results confirmed that the effect of paclobutrazol was stronger than prohexadione calcium on apple cultivars Fuji Zehn Aztec and Red Braeburn under high density planting system.…”

Influence of prohexadione-calcium on temperate fruit crops – A Review

“…The higher fruit mean weight by 18-44 percent in apple cultivars Empire and Royal Court was noticed by prohexadione spray (Cline et al, 2007). In a study, Jacyna and Lipa (2011) reported that fruit diameter was reduced by 125 mg/l pro-ca (A-trees), but fruit shape (L/D ratio) and mass were reduced by 250 mg/l pro-ca (B-trees), and such reduction was also exhibited by C-trees treated with 250 mg/ l prohexadione-calcium. Prohexadione-calcium at 1.0 percent and 1.5 percent significantly increased mean fruit weight compared to untreated plants in Hass avocado plants (Mandemaker et al, 2005).…”