SHOOT GROWTH, FRUIT PRODUCTION AND RETURN BLOOM IN ‘CONFERENCE’ AND ‘DOYENNÉ DU COMICE’ TREATED WITH REGALIS (PROHEXADIONE-CALCIUM)

Chemical growth reduction of ‘Conference’ and ‘Doyenné du Comice’ pears by Regalis (prohexadione-calcium) was studied and compared to the formerly used growth retardant chlormequat chloride (CCC). Like CCC, multiple applications of Regalis reduced cumulative shoot growth in both pear cultivars. Reduction in cumulative shoot length of the trees resulted from both a reduction in average shoot length as well as the number of shoots >10 cm length. Mostly, the reduction in average shoot length was somewhat stronger than that of the number of shoots >10 cm. Compared to CCC, return bloom of Regalis-treated trees was generally less. Regrowth of shoots and loss of terminal flower buds was noted to be one of the reasons for reduced return bloom. It is recommended not to use too high dosages of Regalis and to use additional alternative methods for growth reduction like root pruning or trunk incisions.