- The area devoted to pear production in the United States (U.S.) is declining due to lack of precocity and high
cost of production. The U.S. pear industry currently lacks "modern" orchard systems characterized by compact
trees that produce early, high yields of large, high quality fruit. Tall, shaded canopies are not economically sustainable
and are at a competitive disadvantage for attracting and sustaining a labor supply. There is broad and deep
consensus in the pear industry that developing size-controlling rootstocks is imperative to remain competitive nationally
and globally. Currently employed rootstocks in the U.S. are Pyrus communis seedlings and clones, none
of which achieve more than about a one-third size reduction, and P betulifolia seedlings. Quince (C. oblonga),
used with interstems in Europe and South America, is utilized commercially (without interstems) in the U.S. only
for 'Cornice' in southern Oregon and northern California. This is due primarily to a lack of cold hardiness needed
in more northern production areas, a lack of graft-compatibility with the other major scion cultivars, fire blight
and iron chlorosis susceptibility, and relative lack of productivity versus other rootstocks, especially in California.
Current evaluative trials rely on older U.S. and imported selections, and include the NC-140 Multistate
Rootstock Research Project and several individual programs in California, New York, Oregon and Washington.
A fundamental deficiency is the lack of a mature pear rootstock breeding program, despite access to the USDAARS
National Clonal Germplasm Repository (NCGR), which holds a major worldwide collection of Pyrus and
related genera. International breeding programs focus on increasing yield efficiency, but also graft compatibility,
fruit quality and size, high soil pH tolerance, winter hardiness, warm climate/low chilling adaptation, drought and
salt tolerance, and resistance to fire blight, pear decline, and pear scab. An intensive planning and implementation
effort is needed to develop the necessary contacts, collaborations, explorations, and importation logistics to
acquire the most promising clonal selections for propagation and testing. Basic research needs include effects of
dwarfing rootstock on tree architecture and fruiting, the underlying mechanisms of dwarfing functional in pear,
the inheritance of key traits, and selection criteria for breeding. Propagation and orchard systems have also been
identified as major research needs.
- Elkins, R., Bell, R., & Einhorn, T. (2012). Needs assessment for future US pear rootstock research directions based on the current state of pear production and rootstock research. Journal of the American Pomological Society, 66(3), 153-163.