Krymsk® 6
(cv. LC 52) USPP#16,114
Krymsk® 6 is a promising sweet cherry rootstock having more precocity than Mazzard or Colt, yet not as precocious as the Gisela® series. Krymsk® 6 has more precocity and about 10% less vigor than Krymsk® 5. Krymsk® 6 has tolerance to stress conditions, such as high temperatures and low soil moisture. Krymsk® 6 is well suited to varieties needing improved precocity. Fruit maturity may be advanced by 1 to 3 days relative to Mazzard. Krymsk® 6 is sensitive to the pollen spread ILAR viruses and can produce many suckers in heavy soils.
PARENTAGE: P. cerasus x (P. cerasus x P. maackii)
ORIGIN: Krymsk Experimental Breeding Station, Krasnodar Region, Russia
OLDEST TEST SITES IN THE US: Sweet cherries--2000 in California, Oregon, Washington and New York.
COMPATIBILITY: Sweet cherries and many sour cherries (Montmorency not tested). Graft union similar to Gisela® 5.
VIGOR: 70% of Mazzard seedling.
GROWTH UNIFORMITY: Excellent.
ANCHORAGE: No problems reported.
PRECOCITY: More precocious than Krymsk® 5..
YIELD EFFICIENCY: Good with sweet cherry. Crop load management needed to keep fruit size up.
FRUIT MATURITY: Fruit may ripen 1-3 days ahead of Mazzard, similar to Mahaleb.
SUCKERING: Produces some trunk and root suckers. Can be excessive in heavy soils.
CHILLING REQUIREMENT: Appears to be higher than Mazzard seedling.
COLD HARDINESS: Excellent for all but the coldest growing sites in the US.
NEMATODE RESISTANCE: Unknown. No problems have been encountered.
EFFECT OF ROOTSTOCK ON BACTERIAL CANKER SUSCEPTIBILITY: Unknown.
OAK ROOT FUNGUS TOLERANCE: Untested.
PHYTOPHTHORA SENSITIVITY: No problems reported.
VERTICILLIUM RESISTANCE: Unknown.
DISEASE PROBLEMS--OTHER: Very sensitive to PNRS and PDV viruses.
ASPHYXIA TOLERANCE: More experience is needed.
DROUGHT TOLERANCE: More tolerant of low soil moisture and high temperature stress than Gisela® rootstocks.
CROWN GALL SUSCEPTIBILITY: Level of susceptibility is unknown, but not extreme.
HIGH PH TOLERANCE: Unknown.
CALCAREOUS SOIL TOLERANCE: Moderate.