DWARFING SWEET CHERRY BY ROOTSTOCK, COMPACT OR SPUR SCION AND GROWTH REGULATORS

Theoretically, there are many rootstocks which can serve this purpose; however, those with a true dwarfing effect (e.i. Pr. fruticosa "Oppenheim", Pr. dawyckensis GM61, and some hybrids between Prunus species) also display undesirable side-effects (grafting incompatibility, poor growth, loss in yield and fruit quality). At the present time, the use of semi-dwarfing rootstocks such as some Pr. cerasus clones (e.i. "Vladimir", "CAB 6P" and "11E" or Pr. avium x Pr. pseudocerasus ("Colt" type or Pr. avium x Pr. mahaleb selections seem to be more advisable.

From the collected data, it appears that the use of an interstock consisting of a weak clone of sour cherry (e.g. "North Star" is a feasible alternative for all 5 varieties assessed over 7 years; some of them reduced the tree canopy size by about 50%.

Very attractive possibilities also exist on the use of radiation-induced compact mutants (already available for some cv) or of selections obtained from these by subsequent crossing (e.g."Starkrimson"). The yield efficiency of these trees can be significantly higher than those of corresponding standard clones (as in cv "Lambert"); thus allowing considerable increased planting density and precocity of bearing from the first years. Some dangers exist in using this sort of material, such as possible regression to the standard type as noted already in cvs "Bing", "Van" & probably "Stella".

Finally, the possibility of using growth retardants (MB 25105, SADH+CEPA, Paclobutrazol, etc.) during the first years after planting, in combination with appropriate summer pruning operations, has been outlined.

Download Adobe Acrobat Reader (free software to read PDF files)