Prohexadione-Calcium Controls Vegetative Shoot Growth in Apple

Abstract

Prohexadione-calcium (Phd-Ca) (BAS 125W or 9054 W) applied at petal fall (PF) or within 10 days of PF to apple trees as a single spray or as multiple low-rate sprays reduced the current season's shoot growth. Sprays applied 2 to 3 weeks after PF were less effective. Timing of the initial spray was more important than rate in achieving early growth suppression, but rate was most important for maximum season-long growth control. Reduced shoot growth enhanced spray coverage and reduced dormant pruning time by as much as 23% over control trees. An effective cumulative dose (ECD) of 250 mg?L 21 (based on dilute or tree-row-volume equivalent) active ingredient Phd-Ca applied as a single spray or in several low-rate sprays generally produced season-long control of vigorous shoot growth. However, under some highvigor growing conditions a higher ECD (500 mg?L 21 or greater), applied in multiple low-rate sprays, was required to achieve an acceptable level of growth suppression. When shoots resumed growth in mid-season, a single spray (28 July) at 125 mg?L 21 provided additional suppression of shoot growth. During this 5-year study, there were no adverse effects on fruit quality and little or no effect on fruit size. There was no appreciable carryover effect on the next season's shoot growth or fruit size, and there was no additive effect from successive annual applications.

Redução da poda hibernal e aumento da produção de pereiras 'Hosui' pelo uso de prohexadiona cálcio

“…No entanto, a intensificação dos trabalhos de poda, para restringir o desenvolvimento vegetativo das plantas, pode aumentar os custos de produção no manejo da pereira. Por isso, o controle do desenvolvimento vegetativo por meios químicos pode ajudar a reduzir o crescimento excessivo, limitar o tamanho das plantas ou restringir o crescimento em determinado momento, o que permite melhor equilíbrio entre o desenvolvimento vegetativo e a frutificação (Miller, 2002).…”

Photosynthesis, Shoot Growth and Fruit Quality in ‘Fuji’/M.9 Mature Apple Trees in Response to Prohexadione-calcium Treatments

“…그러나 200mg･L -1 농도에서 신초생장이 과도하게 억제되고 과실비대 및 품질이 감소되 었다는 보고 (Basak and Rademacher, 2000)가 있는가 하면 250mg･L -1 농도로 살포해도 M.106 및 M.111 대목에 접목한 사과나무에서는 신초생장 억제효과가 없었다는 보고 (Miller, 2002)도 있는 등 연구자에 따라 결과의 차이가 크게 보고되 고 있다.…”

Impact of Repeated Yearly Applications of Prohexadione-Calcium On Vegetative and Reproductive Growth of ‘Golden Delicious’/M.9 Apple Trees

“…Treatment with Pro-Ca reduced shoot length by 21-71% in apples depending on the dose, timing of treatment and cultivar (Miller 2002). Similar effects were observed in 'Smoothee Golden Delicious' (Medjdoub et al 2004), 'Empire' (Cline et al 2008), and'Royal Gala' and'Fuji' (Mata et al 2006) apple trees.…”

“…While Medjdoub et al (2005) and Greene (2008) have reported that Pro-Ca increases fruit set, other researchers explained it as ineffective (Costa et al 2000;Miller 2002). In the present study, Pro-Ca has no significant influence on fruit set compared to control.…”

“…In fact, the second Pro-Ca application of this experiment was performed at 30-40 DAFB. It is evident that repeated sprays of Pro-Ca have been a limiting factor in the efficiency of treatments as well as the time of application (Miller 2002;Cline 2006). In this trial, the shoot growth of 'Golden Delicious' apple trees continued until 70 DAFB in control, but more than 80% of the total shoot growth was completed in 45 DAFB.…”