Use interstems to improve apricot tree health (BIOFRUITNET Practice Abstract)

Summary in the original language of the document

Interstems improve economic return since the lifespan of trees, and thus fruit production can be prolonged.
Practical recommendations and information
• ADVANTAGE
o Interstems used as a tree trunk forming part have a high positive impact on tree health
o Delay flow of sap in the tree in the spring
o Regulation of growth vigour, smaller tree crown volume (use of Prunus persica as interstem)
o Delay tree flowering time, decreasing frost damage in case of late frost event during tree flowering
ob Modification of ripening time, early ripening according to used interstem
o Regular and high annual harvest
o Improved fruit quality, fruit size is bigger
• DISADVANTAGE
o The interstem technique is a very expensive process since it needs an extra year in the nursery
• RECOMMENDED VARIETY FOR INTERSTEMS
o Plum variety Stanley (Prunus domestica) has good compatibility with broad range of rootstocks and apricot varieties
o Greengage (Prunus domestica subsp. italica) is used as interstem at the Research Institute for Organic Agriculture FiBL in Switzerland. By this the stem of the variety starts at a higher position (“high grafting”) that can help to reduce infections with, e.g., Pseudomonas syringae. It also helps if the chosen rootstock and variety are incompatible.
o Peach variety Redhaven (Prunus persica) reduce growth vigor, tree crown volume is lower
o Different Prunus species and varieties can be used according to desired impact – tree vigour, tree flowering time, fruit ripening, etc.
• GRAFTING
o Chip budding of interstem on semi-dwarfing and dwarfing or vegetative propagated rootstocks
o English copulation as a method of grafting variety on interstem
o Good compatibility of the variety used as the interstem with rootstocks and grown varieties is
required
• Other reasons for interstem grafting are creating compatibility between incompatible tree varieties via inserting a section of stem compatible with both rootstock and variety
• Nowadays, the offer of apricot varieties is large, but reliable data concerning variety choice for use as interstem and their suitability to organic systems are still lacking, further testing is needed