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.
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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