Sam Richardson’s Northern California pecan trees didn’t know how to react to a very wet spring and temperatures that made swings from 50 to 100 degrees — all before the July 4 weekend.
“The trees just don’t know what to do,” says Richardson, who manages 1,000 acres of tree nuts, as well as field and row crops, for Brouwer Ranch near Durham, Calif. The operation includes 170 acres of pecans.
Despite the wide swings in temperatures and precipitation, the trees entered July in great shape, he says.
“They came out of the harsh spring very healthy and with really good vigor. The nutlets were still small at the end of June. That may be a little behind normal development, but not much.”
The trees are on heavy, former rice ground, clay soils, which held much of the early rain allowing Richardson to delay his first irrigation until late June. Normally, he starts running the solid set sprinklers towards the end of April and has completed two or three irrigations by the first of July.
His pecan orchards include an 80-acre block of 22-year-old trees and another 90 acres of trees that are three years younger. They display opposite bearing patterns. This is an on-year for the 80-acre block, but an off-season for the 90-acre block.
Richardson expects 2011 production from trees in the latter block to be less than 2,000 pounds per acre. By contrast, last year, they yielded about 3,500 pounds per acre, which helped boost the ranch’s average pecan yield for 2010 to more than 3,000 pounds per acre, the highest ever.
Ironically, a year ago Richardson was debating the wisdom of even growing pecans. But, he wanted to wait to determine if an aggressive tree thinning and hedging program started in 2005 would pay off with higher yields. Yields rebounded better than expected and the quality was good, along with pecan prices.
If yields had not gone up, he was going to replace the trees with walnuts.
To open up the orchard, Richardson removed about half the original pecan trees in the two blocks. One block went all the way back to 1989.
“I’m still learning how to grow pecans,” says Richardson, who sought the help of pecan expert Bruce Wood, a USDA-ARS horticulturist at the Southeastern Fruit and Tree Nut Research Laboratory, Byron, Georgia.
“We tried different hedging programs before we figured out what works with our climate and soils. One of the biggest lessons I’ve learned is how much water and sunlight the trees needed. It took three years to regain much of the lower part of the canopy that had been shaded out. Then, we started seeing increased yields.”
Trees in the 80-acre block were planted originally on a square pattern of 28 feet between trees in adjacent rows and between trees within rows. Half the trees were Pawnee and half were Shoshone pollinators.
By the time he was done re-configuring that orchard, Richardson had removed three-fourths of the Shoshone and kept all of the Pawnee. The Shoshone had a very pronounced alternate bearing production pattern, he says. The increased production from the Pawnee with this new pattern more than offset the loss of Shoshone yields. “It’s worked out really well,” he says.
When planted in 1993, the trees in the 90-acre orchard were also placed on a 28-foot square pattern. The work rows were originally east and west, but he changed the irrigation system so the rows ran north and south to gain extra sunlight.
Ninety percent of the trees were Pawnee. The rest were Shoshone, Kanza, and Navajo for pollinators. Richardson changed that arrangement, keeping all of the original pollinators and removing every other Pawnee. That resulted in a diamond-shaped tree spacing, measuring 56 feet between and down the rows, and leaving 40 feet between trees at a 45 degree angle.
His rigorous hedging program includes topping every row of trees annually to a height of about 38 feet. This makes it easier to get good spray coverage of the tops and to achieve more effective shaking when harvesting pecans, along with the added sunlight. In the 80-acre block, Richardson hedges every fourth center on a four-year cycle, going down every fourth row and hedging both sides, moving over a row the following year. Because of the spacing pattern on the 90-acre block, he hedges one side of the trees each year on a four-year cycle. He goes through the orchard at a 45-degree angle to the work rows, hedging every other center, then down the work rows every other center.