Plum of a Rootstock May Boost a
April 1, 1997
Almond growers who today can't grow
Nonpareil--America's premium almond variety--might be able to do so in a few
years, thanks to a plum rootstock called Deep Purple.
Almonds and plums are both members of the Prunus plant family, along
with prune, apricot, plumcot, cherry and peach. U.S. almond growers typically
produce new almond-bearing trees by grafting an almond scion--the trees
upper, fruit-bearing part--onto a peach rootstock, the rooted portion.
Unfortunately, the premium Nonpareil variety scions can't be grafted
successfully onto certain choice plum rootstocks. So, some growers now have to
settle for less popular almond varieties that can be grafted to other
rootstocks. Nonpareil almonds might, however, graft well to Deep Purple
rootstock. Thats according to preliminary tests at
USDAs Agricultural Research Service.
Deep Purple, a hardy plum introduced by the University of Minnesota in 1965, hasn't been
tried for this job until now.
In the ARS experiments, 24 Deep
Purple grafts of scions of other Prunus relatives of almond--prune,
apricot and plumcot--were still strong after 4 years.
This spring, several dozen Nonpareil scions will be grafted onto Deep Purple
rootstock, then readied for ARS test-planting in commercial orchards next year.
Like most other plum rootstocks, and unlike peach, Deep Purple can thrive in
orchard sites where water tends to accumulate. It shows tolerance to bacterial
canker. It also resists two kinds of destructive, microscopic worms--called
nematodes--better than some other candidate rootstocks. Growers today rely on a
soon-to-be-banned soil fumigant, methyl bromide, to fend off these orchard
Scientific contact: Craig A. Ledbetter, USDA-ARS
Research Laboratory, Fresno, Calif., phone (209) 453-3064, firstname.lastname@example.org.