Almond-Marianna 2624 Performance
John Edstrom, UCCE Farm Advisor
Stan Cutter, Nickels Soils Lab
Prior research at Nickels Soil Lab suggested that many almond varieties can be
quite productive when planted on Marianna 2624 plum rootstock. But this rootstock has a
considerable dwarfing effect on most almond varieties and requires tighter tree spacing to
realize its maximum bearing potential. Mission, Ruby and Padre cultivars have shown
excellent compatibility with M2624. However, the Butte cultivar has shown inconsistent
performance on M2624.
This test planting was established in 1989 to evaluate 4 almond
varieties in a close planted hedgerow on M2624 rootstock. Commercially harvestable
replications were designed into the test for yield data collection. Butte, Mission, Ruby
and Padre almonds were planted as single rows at 10' x 20' spacings for 218 trees/acre.
Yields continued to climb in this 10th leaf test orchard (Table I.).
All varieties exceeded 2000 lbs./Ac., with Padre highest at 3226 lbs./Ac. Mission again
lagged behind with 2251 lbs./Ac. Kernel sizes were normal for the four varieties as
presented in Table II.
All four varieties have continued to perform satisfactorily on M2624
rootstock, with few tree losses occurring. Some canopy expansion is still required to
adequately fill allotted space and reach optimum bearing potential. The twenty feet
distance between rows for M2624 may prove to be too wide given the shallow soil at this
test site and dwarfing effect of plum rootstock. A more appropriate row width would be 18
feet. Suckering (typically troublesome with M2624) has been reduced by deeper tree
planting. Growers considering M2624 blocks may want to special order trees high budded to
allow deeper planting to help prevent root suckers.
For the second consecutive year, M2624 production levels exceeded those
of the same varieties on Lovell rootstock planted nearby at 15' x 20' on somewhat deeper
soil. Also, Padres on M2624 are not leaning over in these short statured trees like the
taller Padres on Lovell.
The leaf scorch symptoms reported previously for the Butte variety on
M2624 did not develop this season. Usually, beginning in June, marginal leaf necrosis
occurs on random limbs in scattered trees. Affected trees appear smaller in size while
individual limbs affected show reduced vigor and defoliate before harvest. No disease
organism, salt, fertilizer, chemical, or other cause has been found to explain this
symptom.
Table I.
