California is the national leader in tree nut production. Almond, walnut, pistachio and even pecans are thriving with increased acreage and consumer demand. So what’s with the macadamia nut?

There are reasons why this round, tasty nut isn’t grown extensively in California and reasons why some growers are committed to macadamia production.

Macadamia nut trees are subtropical plants, but varieties have been developed to withstand light frosts. Macadamia trees grow best when temperatures are between 50 F and 80 F. When mature they can take more temperature extremes but not hard frosts or 100-degree-plus temperatures. This limits their growing regions in California to southern, coastal areas where they have to compete for water and land with urban interests.

San Diego County macadamia nut grower Jim Russell has the climate and the six acres for 200 trees, but costs for the three-and-a-half to four-acre feet of water per year the trees need make it difficult for him to find a reason to expand production.

“There is a market here for macadamias,” says Gary Bender. Dr. Bender is a UCCE farm advisor emeritus in San Diego County and one of the few people with extensive knowledge about macadamia production in California.

“I’ve been a speaker at most of the annual macadamia nut association meetings and have been attending them since 1975,” Bender said. He estimated there are 40 to 60 acres of macadamia nut trees in San Diego County and additional acres in Ventura and Santa Barbara counties.

Macadamia nut trees are evergreen like citrus and long lived. Russell said his trees are about 32 years old and in the prime of their production years. It is not unusual to see 100-year old trees. The trees are propagated by grafting a variety on a rootstock. The trees begin to produce commercial crops by their seventh to 10th year depending on climate and nutrition. Russell, who farms in the Fallbrook area, said there are no serious pests to deal with in macadamia production. Navel orange worm, carob moth and southern green stinkbug are occasional pests.

In addition to the competition for land and water, the third strike for macadamia production is labor. Macadamias are unique among tree nuts in that their nut crops do not mature at one time. Harvest takes place over several months in the late summer and fall. Nuts drop from the tree when mature. They can be shaken off, Russell said, but if they are still green, they will be rejected.

Harvest machinery used in almond or pistachio could be used for macadamia harvests, but Bender said the small number of production acres make that uneconomical. Russell said he harvests by hand once or twice a week through the harvest season, raking the dropped nuts and picking them up by hand.

Two species of Macadamia produce the edible seeds or nuts: Macadamia integrifolia and Macadamia tetrapyhlla. Both are native to Australia. Hawaiian growers rely on the integrifolia, which produces a uniformly round and smaller nut. Tetraphylla is less tolerant of temperature extremes, but its advantages include a sweeter tasting nut with a higher carbohydrate content and lower oil content. Integrifolia’s higher oil content makes it a better candidate for roasting and salting.

A macadamia tree in full production should yield about 50 pounds – nut and shell – annually, Russell said. He markets his crop at farmers markets or by mail order. There is a grower’s cooperative, Gold Crown Macadamia Association that can handle drying, processing and shipping for its members.

Hawaii remains the largest producer of macadamia nuts in the United States. Last year growers there saw record production and prices. Total crop was 47 million pounds on a wet, in-shell basis from 16,000 acres. The average farm price increased 10 cents from last season to 97 cents per pound, beating the previous high set in 1988-1989 at 90 cents per pound.

Macadamia could be a good fit for Florida growers who are losing their citrus to Huanglongbing, Bender said.

UCCE San Diego, California Macadamia Society and Gold Crown Macadamia Association are hosting an information meeting for growers on Sept 30 in Escondido.

For more information on the meeting, contact California Macadamia Society, (760) 728-8081 or 760-580-5516 or by email at [email protected].

For more information, visit http://www.macnuts.org/fieldday.htm.