BUDBREAK INDUCTION IN APPLE TREES BY ERGER AND CALCIUM NITRATE APPLICATION

Abstract

In mild winter climates, the budbreak promoters application is one of main management strategies used to decrease problems of insufficient winter chilling on temperate fruit trees. Despite of the high efficiency of some chemicals on budbreak induction, the high toxicity showed by these compounds is one problem related to its use. Erger, an organic nitrogen compound, combined with calcium nitrate, has a similar effect to that of hydrogen cyanamid, with the advantage of being less dangerous to the environment. The objective of this study was to evaluate the effects of Erger and calcium nitrate combinations on budbreak induction of ‘Imperial Gala’ and ‘Suprema’s Fuji’ apples. The experiments were carried out in Cacador, Santa Catarina, Brazil (26°46’S, 51°W), at 960 m a.s.l., during two growing seasons (2006/2007 and 2007/2008). The treatments tested were control, standard (mineral oil 3% + Dormex® 0.7%), and Erger + calcium nitrate at concentrations of 3, 5, and 7%. Full bloom date, axillary and terminal budbreak, fruit set, and mean fruit weight were evaluated. All Erger + calcium nitrate concentrations anticipated the full bloom date in relation to control treatment, but were not observed differences with mineral oil 3% and Dormex® 0.7%. The budbreak promoters increased significantly axillary and terminal budbreak and increasing the uniformity of budbreak. Fruit set was not affected by Erger + calcium nitrate concentration in relation standard treatment. The combinations of Erger and calcium nitrate showed similar uniformity and performance to mineral oil and hydrogen cyanamide on budbreak, showing to be an efficient alternative to budbreak induction in ‘Imperial Gala’ and ‘Suprema’s Fuji’ apples.