Rootstocks plums

For general advice, see Apples (p.294). Most European plums will set some fruit without cross-pollination, but nearly all will yield better when cross-pollinated by another European cultivar. Japanese plums must be cross-pollinated by either a Japanese or American type. American plums also need cross-pollination for best yields. Rootstock choice can further influence your plum trees success. Ask a specialty fruit nursery for help in selecting a suitable combination of trees on appropriate rootstocks. 

Prune and plum have less crop tolerance to simazine at high rates than the other stone fruit (Chaney et al, 1966 Elmore et al, 1970 Almoida et al, 1987). In a field experiment in California where simazine was applied for 2 years on French prune, Marianna 2624 plum rootstock, or Imperial prune on Myrobalan 29C plum rootstock, there was some phytotoxicity observed, though weed control was excellent and trunk diameter increased in most instances over an untreated check (Elmore et al, 1970). Simazine has been used with good crop tolerance at low rates for winter weeds, particularly in some of California s heavier soils. In California approximately 800 pounds of simazine were applied to 900 A of plum in 2004. 

Since plums and sweet cherries generally flower earlier than apples, a frost-free location which is sheltered from the wind is preferable. Antifrost irrigation is not possible for stone fruit. The soil should be well-drained. Plums tolerate a somewhat heavier soil than cherries. The choice of rootstock can compensate for these disadvantages, however. 

Plums are deciduous trees that grow from 5 to 20 depending on soil, rootstock, and cultivar. Japanese plums Prunus salicina) bear fruit on spurs—short branches that elongate only a fraction of an inch per year— 1 year old or older. European (P domestica) and hybrid plums bear fruit on spurs 2 years old or older. Plums are hardy in Zones 4-10, depending on species and cultivar. 

Ornamental plum—These trees produce red foliage and red fruit which is suitable for jams and jellies. The scientific name for the ornamental plum is Prunus cerasifera which is also the myrobalan plum. The major value of the myrobalan plum is its use as a rootstock for other stone fruits. 

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