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Fruit Varieties Journal
(Fruit Var J)

American Pomological Society

Volume 37 Number 1 Article 3 Pages: 24-29
Year 1983 Month 1
Title: Pear Rootstocks: Present and Future
Authors: M.N. Westwood and P.B. Lombard
Early work on pear rootstocks in the west centered around the search for resistance to fire blight (Erwinia amylovora (Bur.) Winslow, et al). F. C. Reimer collected blight resistant stocks such as Old Home and Farmingdale of European origin as well as a number of primitive species from Asia (7, 8). With the appearance in the 1950's of the new disease "Pear Decline," research was renewed on pear rootstocks in the western states (2, 11, 16, 21). It was learned that Pear Decline is caused by a pathogen, probably a mycoplasma, injected into the trees by infected psylla insects feeding on the leaves. The pathogen moves through the living bark down ward to the root. If the rootstock is susceptible, phloem necrosis occurs below the graft union, causing the tree to die (1, 5, 6, 15, 19). Resistance to Decline was shown to be genetic ally controlled (12).

In 1960 we began a series of pear rootstock trials to study not only Pear Decline but a wide array of other environmental and biotic factors, in cluding growth control and cropping efficiency (3, 4, 9, 10, 14, 18, 20). We have learned that no single rootstock is suitable to every situation.

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