Orchard performance of new plum cultivars on two rootstocks in a trial at Holovousy in 1998-2003

Thirteen plum cultivars on two rootstocks (Myrobalan and Wangenheim Prune seedlings) were studied in a trial established in the spring of 1998 at spacings 5 × 1.5 m. Trees were trained as spindles. Čačanska najbolja was the most vigorous in this trial, followed by Čačanska rana, Herman and Domestic Prune. The weakest tree vigour was observed on Wegierka Dabrowicka, followed by Čačanska rodna and Empress. Čačanska najbolja, Wegierka Dabrowicka and Valor had the highest yield per tree, whereas Čačanska rana had the lowest yields. Bluefre was the most precocious cultivar. Wegierka Dabrowicka had the highest yield efficiency followed by Empress and Valor. On the contrary, Čačanska rana, Early Blue and Domestic Prune belonged to the least productive cultivars. Trees on Wangenheim Prune seedlings grew about one third weaker than those on Myrobalan seedlings but their yield efficiency was about 31% higher although their yields per tree were about 12% lower. The largest fruits were recorded with Bluefre. Čačanska rana, Empress, Valor and Oneida were also ranked among large fruit varieties with minimum differences between them. The mean harvest season of evaluated cultivars started by Herman on the 12th July and ended by Oneida on the 9th September. Valor and Empress had the best performance of tree growth, bearing habit and fruit size, which indicates their good suitability for the modern types of plum orchard. Bluefre may also be of some interest for growers because of the best precocity and large fruit size, and Oneida for prolonging the whole harvest season.