LONG-TERM PERFORMANCE OF OWN-ROOTED ‘CHANDLER’ WALNUT COMPARED TO ‘CHANDLER’ WALNUT ON PARADOX ROOTSTOCK

A trial planted in 1991 compared micropropagated un-grafted ‘Chandler’ to those conventionally grafted onto seedling Paradox (J. hindsii x J. regia) rootstock.
From 1995 through 2002, own-rooted ‘Chandler’ had significantly greater trunk cross sectional area than did ‘Chandler’ on Paradox rootstock.
Yield was significantly greater on own-rooted ‘Chandler’ from 1995 through 2000, but not in 2001 and 2002. Low vigor and dieback were first observed in 1998 on some own-rooted trees. Pratylenchus vulnus was detected in soil and root samples taken from every tree in the trial on at least one of the sampling dates.
Overall, soil nematode populations on own-rooted trees were significantly higher than on Paradox.
Although seven trees on Paradox rootstock were found to have crown gall, no infections have been found on own-rooted trees.
Own-rooted English walnut trees may have potential in areas where commonly used rootstocks (J. hindsii and J. hindsii x J. regia) are undesirable because of hypersensitivity to cherry leaf roll virus.
Although the micropropagated ‘Chandler’ has been productive under the conditions in this trial, root-lesion nematode susceptibility may limit usefulness where soil populations exist.

XXVI International Horticultural Congress: Key Processes in the Growth and Cropping of Deciduous Fruit and Nut Trees

J.K. Hasey, B.B. Westerdahl, B. Lampinen

micropropagation, lesion nematode, Pratylenchus vulnus, crown gall, rootstock

https://doi.org/10.17660/ActaHortic.2004.636.9