First step in grafting preparation is budwood collection. SCH collects budwood from growers in the Nelson region as it is known that there is lower risk of PSA in the South Island.
Budwood is collected in winter before winter pruning and after leaf fall. Natural leaf fall helps with budwood storage as we take away the risk of damage by removing the leaves manually. Our growers then follow high standard budwood collection protocols to ensure best possible budwood for grafting. Some of the QC criteria is straightness and maturity of budwood as well as thickness and internode distance. Strict sanitation protocols are followed to ensure long lasting storage in our cool stores. Budwood is then packed in bags which are all marked and colour coded with KPIN, variety and grower’s information. We usually collect two sizes, one suitable for grafting Bruno and the other for Bounty rootstock.
Rootstock preparation starts with planting seedlings and cuttings in early spring (August – September). We grow them in our greenhouses where we create best possible conditions. During that time, plants grow strong roots and thick stems. These plants are specifically grown for rootstock only and most commonly occur in two varieties – Bruno and Bounty. Each of them has its own characteristics.
At the start of summer, plants mature enough for grafting. Grafting is a process where fruiting varieties are joint with rootstock ensuring plants produce good fruit for harvest. In SCH nurseries we start grafting late November and continue until February.
Just before grafting we cut the rootstock to certain height (500mm) which is most suitable for growth in orchards. Pre-grafting cut is done up to a week before grafting which ensures the thickness and turgidity of the plant. After that we remove the top 2-3 leaves to make space for grafting scion onto rootstock.