When primary floral buds of blackberry are injured by low temperatures, secondary buds often differentiate and produce a partial crop. The objective of this study is to determine how quickly secondary buds differentiate in their subsequent yield potential in response to primary bud injury at various time intervals during plant dormancy. Tree growth, yield and fruit chemistry data will be recorded for five years. Yield will be correlated with blackheart to determine if cold-induced xylem injury actually results in yield decline. The most commonly planted apple on a semi-dwarf rootstock requires five to seven years to come into production.
Pear trees require six to eight years to produce a commercial crop.
Recently, a propagation technique known as air root pruning has been devised for oak trees that greatly reduces the time required before the onset of fruit production. The objective of these studies is to determine if this type of production technology can be modified and transferred to induce precocity in apple and pear trees. Those rootstocks that impart cold tolerance to peach fruit buds are being identified. This project is being coordinated with project leaders in Kansas, Ohio and South Carolina. Twenty different dwarfing rootstocks were grafted onto Fuji apple trees and were planted and trained in a vertical axis system.