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Walnut grower benefits from closer tree spacingWalnut grower benefits from closer tree spacing

April 27, 2009

3 Min Read

Although it’s too early to tell much about the nut set, walnut grower Gary Anderson, Willows, Calif., is encouraged by what he saw in his Hartleys at the start of the third week of April. “Right now it looks like if they all set, it might be a big crop,” he says. “There are a lot of doubles and triples. Usually that indicates the possibility of a yield of 2 tons or maybe a little more per acre.”

Anderson is a partner in Ratliff and Demmer Farms. The Glenn County operation includes 500 acres of producing walnuts along with about 100 acres of young trees a year or two away from production. In addition to Hartley, he has Chandler and Howard varieties.

The trees are planted with closer spacing than most growers use. The practice is designed to start production earlier in the life of the trees while concentrating production of nuts in the tree canopy. In this case, the closer spacing was also adopted to make the most of the orchards’ lower quality (Class II and Class III) soils. The goal was to encourage earlier, more consistent yields, Anderson reports.

One of his Chandler orchards, now starting its 17th year, is planted in 24 x 24-square foot spacing. That compares to the typical 30 x 30-foot spacing for Chandlers grown on better ground along the Sacramento River. The first year of production of the sprinkler-irrigated trees was in 1997, when they were six years old. Production continued to climb, reaching 6,000 pounds of walnuts per acre in 2001. Yields remained the same the next year before rising to 6,500 pounds per acre in 2003 and 6,800 pounds per acre in 2004. The year after that, Anderson harvested a 6,700-pound crop, followed by a 6,500-pound crop in 2006. Like other California walnuts orchards, Anderson saw his production drop in 2007 when his walnuts yielded 5,700 pound per acre. Last year, his trees rebounded, producing a 7,400-pound crop.

A second walnut orchard, three years younger than this one and flood irrigated, is also on the same spacing. In its ninth year, the orchard began producing, posting a yield of 5,000 pounds per acre. Since then, the highest yield for his orchard has been 6,300 pounds per acre.

Each year, Anderson hedges every third row of the Chandlers to provide good sunlight for the trees. Also, he brings in a pruning tower annually to clean up broken branches and low limbs that interfere with equipment. The pruning tower is also used to thin out the center of the canopy every third or fourth year.

Anderson’s third oldest orchard features Hartleys planted in a 30 x 30-foot diamond spacing. Last year, the 11-year old trees produced 4,100 pounds per acre. Anderson is waiting to see how fast this variety closes in before doing any hedging.

“Once the middle of the tree becomes too crowded, I may go in and use the pruning tower to open the center a little to let the sunlight in,” Anderson says.

A 58-acre orchard of sprinkler-irrigated five-year old Howards on a 24 x 18-foot spacing produced its first crop last year, yielding a total of about 20,000 pounds. To help prevent broken branches, the Howards are pruned heavily every year. Anderson plans to start hedging these trees when they are nine or 10 years old. He expects production to double and, possibly, triple this year.

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