Two Step Makes Harvest Music. Alternating Varieties in the Same Row.
Growers who alternate almond varieties in the same row of closely-spaced plantings could sing a happier tune at harvest, says John Edstrom, Colusa, Sutter and Yuba County farm advisor.
His comments at the Nickels Field Day last May were based on field trials at the Nickels Estate in which four consecutive harvests showed a yield advantage to alternating Mission and Padre down the same row. The 1996 harvest produced an 8.5 percent increase in yield for this configuration versus solid rows of Mission and Padre. For all four years, the yield advantage in the mixed rows averaged 9 percent!
Even sweeter music to growers ears could be the indication that alternating varieties down the row appears to stabilize year-to-year yields.
"If this holds true, we can add production to the 'off' years when crop returns are likely to be higher per pound," Edstrom said.
The trend to hedge-row plantings in almonds led Edstrom and the Nickels Estate crew to compare results from traditional single-variety row plantings to the mixed-variety design.
"Today's almond orchards involve closer spacings to maximize early returns," he observed. "However, tighter spacings tend to exaggerate the development of a floral 'wall' during bloom. This can decrease cross-row bee activity and limit cross pollination."
It's not just that bee activity between varieties could be limited by a dense wall of blooms, Edstrom explained. "Expansion of statewide almond acreage is creating more demand for bees and supplies of strong hives are particularly stretched."
On top of that, there's the rapid increase in world supplies of almonds, which could lower prices and increase pressure on growers to maximize production efficiency, he said. "These converging trends make optimal pollination management and innovative orchard designs to increase yields even more important."
Thus the Nickels Estate's Multi-Variety Rows Field Trial which is evaluating solid rows of Padre and solid rows of Mission to rows in which Padre and Mission alternate. Rows of Butte border all experimental rows as an additional pollenizers. All trees are planted to Lovell peach rootstock on 15-foot by 20-foot spacings for 145 trees per acre on Class II soil.
Comparing 1996 yields by variety in the two different planting configurations found a 14 percent increase for Padre production when that variety was alternated in the row with Mission. Mission, however, showed no significant increase last year, although in previous years it also responded with increased yields.
Edstrom notes that, as the orchard matures, the Padre trees alternated with Mission begin to dominate and out-compete Mission for space. He thinks this could shift the ratio of production towards Padre.
The Butte Effect
Remember, the Nickels crew planted rows of Butte alongside each of the experimental rows. "The effect of the 50 percent Butte pollenizers may be important," Edstrom speculates. "The benefit of alternating two varieties down the same row could be even greater if only two varieties were planted in the block."
He thinks that the Butte pollen may be responsible for much of the Mission/Padre set, thus limiting the advantage of alternating. "Orchards with just two varieties could benefit more than this data shows," he notes.
Because Padres tend to stick tight when harvested late, the mixed-variety rows cannot be harvested in a once-over operation, Edstrom cautions. To obtain acceptable nut removal, Padres require earlier shaking than Missions, he explains.
"Two passes down the same row with a shaker is required on the rows where Mission and Padre are alternated," he says. "Sweeping and pickup operations are completed in a single pass that combines the two varieties."
If the yield potential of this two-step tune gets your foot tapping, check out the Nickels Estate planting near Arbuckle. You could find yourself waltzing all the way to the bank.