Premium Lapins cherries can be grown on Krymsk 5 rootstock if proper management techniques are followed.
Choosing the right cherry rootstock is just as important as choosing the right variety. This article provides a synopsis of the all the commercially available cherry rootstocks sold in the Pacific Northwest and how they react to Northwest conditions.
Colt (P. avium x P. pseudocerasus)
Colt was released by the research station in East Malling, England, in the 1970s as a semidwarfing rootstock. However, in Northwest irrigated orchards, it produces a vigorous tree that is similar in size to Mazzard with similarly low precocity. Colt is sensitive to droughty soils and cold winter temperatures. It has been widely planted in California due to its resistance to cherry stem pitting. Colt has also shown resistance to Phytophthora root rot and gopher damage, but is susceptible to crown gall caused by Agrobacterium tumefaciens. In the Northwest, Colt performs well in replant situations where cherries follow cherries on nonfumigated sites.
Gisela 5 (P. cerasus x P. canescens)
Although the most popular rootstock in Germany, Gisela 5 has failed to gain widespread acceptance here. The medium low-vigor of this rootstock coupled with very high fruit production has caused fruit size and quality issues, a problem accentuated when Gisela 5 is combined with productive cultivars such as Lapins and Sweetheart. When properly pruned and grown on deep, fertile soils, it may be suitable for very high density plantings of 400 to 600 trees per acre. Gisela 5 tends to advance both flowering and fruit ripening by two to four days and produces a tree that is open and spreading with wide branch angles, though branching may be sparse. Anchorage is usually adequate, but some growers have taken the precaution to support the tree. Trees on Gisela 5 rootstock have shown good winter hardiness. Gisela 5 does not perform well in heavy soils and needs good drainage. Trees show sensitivity to replant stress so should only be planted on virgin sites or where the soil has been properly treated with fumigants prior to planting.
Gisela 6 (P. cerasus x P. canescens)
Gisela 6 is the most popular rootstock for new plantings in Oregon. Although it exhibits medium to high vigor, it is easy to manage. Recommended planting densities are 250 to 500 trees per acre. It is also very precocious, producing harvestable crops by the third leaf with full production possible by the fifth leaf. Due to these high production levels, trees on Gisela 6 need to be properly pruned from an early age in order to maintain fruit size and quality. Premium fruit quality is possible with cultivars of moderate to low productivity such as Bing, Skeena, and Regina, but more difficult with very productive cultivars. The production of new shoots is much easier to achieve with Gisela 6 compared to Gisela 5 and is one of the reasons for the popularity of this rootstock. Gisela 6 tends to advance flowering and fruit ripening only slightly compared to Mazzard. Trees are open and spreading with good branching. Anchorage can be a problem, especially on windy sites, although most growers in the Northwest do not provide support. It is well suited for a wide range of soil types from light to heavy; however, good drainage is essential.
Gisela 12 (P. cerasus x P. canescens)
Tree vigor and size on Gisela 12 is variable depending upon cultivar combination. Several years of testing in The Dalles, Oregon, and Prosser, Washington, indicated that when combined with Bing, Gisela 12 produced a tree intermediate in size to Gisela 5 and 6. However, grower experience with Regina indicates that Gisela 12 produces a tree approximately 10 percent larger than Gisela 6. Some growers prefer the Regina/Gisela 12 combination, as they find it easier to maintain shoot growth and, ultimately, fruit size. It is both precocious and productive, producing early heavy crops, with full production possible by the fifth leaf. Good fruit size and quality is possible with proper pruning. Gisela 12 is adapted to a wide range of soils, and tree structure is open and spreading and new branches form readily.
Krymsk 5 (P. fruticosa x P. lannesiana)
This precocious, semidwarfing rootstock originated in the Black Sea region of Russia. Grower experience in the Northwest suggests that Krymsk 5 is comparable in size to Gisela 6 with slightly less precocity and yield. Production of Lapins on Krymsk 5 through the eighth leaf in Oregon indicates that premium quality fruit can be produced consistently on this rootstock when properly managed. It is adapted to a wide range of soil types, with reports that it will grow well in heavier soils than Mazzard. Accounts out of Russia indicate that the rootstock is well adapted to cold climates. In addition, early indications suggest that trees on this rootstock might also perform well in hotter climates as leaves remain turgid in extreme heat and don’t show the characteristic cupping of Gisela trees in hot conditions. Low to moderate levels of root suckers can be found growing from the crown, but usually not in the tree row. The tree form is excellent, with wide branch angles. Since this rootstock is easy to propagate by softwood cuttings and layers, and due to its lower per-tree royalty, establishment costs for growers are considerably less with Krymsk 5 than the Gisela series. Krymsk 5 is susceptible to prune dwarf virus and Prunus necrotic ring spot virus.