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MACADAMIA SPP. - Macadamia |
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CULTURE |
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Location: Macadamias do best in full
sun, although in hot climates partial shade can be beneficial.
Windy locations should also be avoided. The brittle branches can
be damaged by wind, especially when laden with a heavy crop of
nuts.
Soil: Macadamias will perform on a wide range of soil types from
open sands and lava rock soils to heavy clay soils, as long as
the soil is well drained. They do best, however, in deep, rich
soils with a pH of 5.5 to 6.5. Macadamias will not tolerate soil
or water with high salt concentrations. In areas with low annual
rainfall, leach the soil regularly.
Irrigation: Macadamias can withstand
periods of drought, but the harvests will be small and of low
quality. Irrigation seems to be more important during certain
critical periods in the crop cycle, particularly from the time
of nut set, through nut filling and through the vegetative growth
period in midsummer. The trees should receive at least as much
water as is normally provided an avocado tree. The actual amount
depends on the soil. Young trees also have higher water requirements
than mature trees. In general it is important to water macadamias
regularly and deeply during dry periods.
Fertilization: Since macadamias grow
slowly, they do not require large quantities of nitrogen fertilizer.
Six months after planting out the trees should receive light applications
of a balanced fertilizer such as a citrus mix or fish emulsion
which contains no more than 1% nitrogen. Applications should be
made at least twice a year. A mature tree should receive approximately
5 pounds of citrus mix per application and young trees proportionally
less. Too much nitrogen may result in chlorosis. Micronutrient
deficiencies are common in some areas, but these can be corrected
with chelated sprays.
Pruning: The object of pruning a
macadamia is to form a tree with a single main stem and a framework
of horizontal branches, starting at 3 ft. above the ground and
from there at intervals of about 1-1/2 ft. In M. integrifolia
there are 3 buds in a vertical row in each of the three leaf axils
of a node. When the stem is is topped, all three upper buds will
grow straight up. Only one of them must be allowed to remain and
to continue the main stem, the other two being clipped off to
a stub of about 3/8 inch. Now the buds below those two stubs will
grow out in a more or less horizontal direction. Only these branches
will flower and fruit. This process is repeated until a good framework
has been established. Macadamias will take heavy pruning but this
may drastically reduces yields.
Frost Protection: Frost protection
is more critical for young trees than more mature ones. While
they are still on the small side, the plants can be given the
standard methods of protection, such as plastic sheeting and such
draped over a frame around the tree. As the trees get larger,
they are more difficult to cover, but they also become more tolerant
of mild frosts
Propagation: Macadamias are easily
grown from seed, but the seedlings may take 8 to 12 years to bear
a crop and the quality of the nuts is unpredictable. Grafting
is the most common method of producing nursery trees and is best
done in spring or autumn. The wood of macadamia is hard, however,
requiring the propagator to have experience to be successful.
The scionwood is girdled some 6 to 8 weeks beforehand, the preferred
wood being healthy mature material of the previous flush. The
recommended graft is the simple whip, using material 3/8 to 5/8
inch thick. The side graft is also successful, and tip, wedge
or cleft grafting is used under greenhouse conditions for working
small seedlings up to 1 ft. high. Budding is also possible as
well as propagation from softwood cutting and air-layering. Cutting-grown
trees take some time to develop an adequate root system and will
need staking when young. Some grafted varieties of macadamias
begin bearing within 2 years, while others not for 7 to 8 years.
Pests and diseases: In Australia
there are a host of pests and diseases that afflict macadamias,
but in the U.S. there are few problems in home gardens. Occasionally,
thrips, mites and scale may be troublesome, and anthracnose can
infect leaves and nuts in humid climates. Canker can also result
from wounds to the tree. Macadamias are fairly resistant to Phytophthora
cinnamoni, and are sometimes used to replant avocado orchards
infected with the fungus. The roots of the macadamia do not appear
to be very attractive to gophers, but deer will browse on the
new foliage.
Harvest: Mature macadamia nuts will
fall to the ground from late fall to spring. It is best to harvest
fallen nuts, since shaking the trees to dislodge the nuts may
also bring down immature nuts. A long pole can be used to carefully
knock down mature nuts that are out of reach. A reasonably good
tree will produce 30-50 pounds of nuts at 10 years age and gradually
increase for many years.
Harvested nuts should be dehusked and spread in a dry place protected
from the sun and allowed to dry for 2 or 3 weeks. To finish drying
put the nuts in a shallow pan and place in the oven at the lowest
temperature setting (100 degrees to 115 degrees F) for
about 12 hours. Stir occasionally and watch that the nuts do not
cook. Excessive heating will damage nut quality. Store the nuts
in a cool, dry area. A heavy plastic bag will prevent nuts from
reabsorbing moisture. When the nuts are dry, the shells can be
removed with a nutcracker. A cottage industry of sorts has developed
around designing nutcrackers that can best cope with the hard
shells.
To home-roast macadamia nuts, place shelled nuts (whole kernels
or halves only) in a shallow pan no more than two deep. Roast
40 to 50 minutes, stirring occasionally. Watch carefully and remove
from the oven as soon as they start to turn tan. After roasting,
the nuts store nicely, salted or unsalted, in airtight jars at
40 degrees to 65 degrees F. They can also be frozen.
Macadamia nuts are excellent raw or roasted. In addition to being
a quality snack, they can be used in almost any recipe that calls
for nuts, including stuffings, fruit salads, cakes, etc.
Commercial Potential: Macadamia
nuts are considered by many to be the prime edible nut. Even at
the high prices demanded, twice that of cashews, the market remains
unfilled. This demand for macadamia nuts has spurred a flurry
of plantings in areas all over the world where macadamias will
thrive. There is a limited but significant commercial production
of the nuts in Southern California.
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CULTIVARS |
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Beaumont (Dr. Beaumont)
Hybrid. Originated in Australia. Discovered by Dr. J. H. Beaumont.
Introduced in 1965 by the California Macadamia Society. Round,
medium to large nut, 65 to 80 per pound. Shell medium-thick, kernel
40% of nut, with a high percentage of grade A kernels. Some nuts
may split on the tree and be ruined. Texture and flavor very good.
Tree upright, ornamental. New leaves reddish, flowers bright pink,
borne on long racemes. Nuts drop over a long period. Recommended
for home gardens.
Burdick
M. tetraphylla. Originated in Encinitas, Calif. Large nut, averaging
40 per pound. Shell thin, about 1/16 inch thick, well-filled.
Kernel averages about 34% of total nut weight, quality good. Matures
in October. Tree bears annually. Not widely planted these days.
Has been superseded by better cultivars. Also used as a rootstock.
Cate
M. tetraphylla. Originated on the property of William R. Cate,
Malibu, Calif. Nuts medium to large. Shell average thickness.
Kernels 40% of nut, cream colored, crisp in texture, flavor good
to very good. Ripens in late October and November continuing over
a period of 6 to 8 weeks. Tree precocious, moderately hardy, shows
no alternate bearing tendencies. The most widely adapted cultivar
for commercial use in California.
Dorado
M. integrifolia. Originated in Hawaii. Introduced by Rancho Nuez
Nursery. Medium-sized, uniform nuts, 7/8 to 1 inch in diameter.
Kernel averages 35% of nut, oil content 75%. Tree medium-tall,
upright, attractive. Begins to bear after 5 years, self-harvesting,
cold resistant. Very productive, often yielding 65 or more pounds
of nuts per year.
Elimbah
Originated in Australia. Imported into California by E. Westree.
Thin shells. Kernel averages 45-50% of nut. Nuts tend to drop
year-round.
James
M. integrifolia. Originated in La Habra Heights, Calif. Medium-sized,
uniform nuts, about 1 inch in diameter. Kernel averages 40 to
42% of nut, quality high, flavor very good, oil content 75%. Tree
very tall, columnar, precocious, often producing after 2 or 3
years. Self-harvesting. Yields more per acre than any other California
cultivar, 60 or more pounds per tree when mature.
Keaau
M. integrifolia. Originated in Lawai Valley, Kalaheo, Kauai, Hawaii.
Medium-sized nut, averaging about 80 nuts per pound; Shell smooth,
medium brown, thin. Kernel 42-46% of nut, color light cream, quality
good. Season August to November. Tree moderately vigorous, upright,
very productive.
Keauhou
M. integrifolia. Originated in Kona, Hawaii by W.B. Storey. Medium
to large nut, averaging about 54 nuts per pound. Shell very slightly
pebbled, medium-thick. Kernel 37 to 40% of nut, quality tends
to vary in different locations. Harvest season relatively short,
with most of the crop maturing within about 3 months. Tree vigorous,
yields well, extremely resistant to anthracnose.
Vista
Hybrid. Originated in Rancho Santa Fe, Calif. by Cliff Tanner.
Small to medium-sized nut, 3/4 to 7/8 inch in diameter. Kernel
averages 46% of weight of nut, flavor excellent, oil content 75%.
Shell very thin, can be cracked in an ordinary hand cracker. Tree
medium-sized, pyramidal, begins to bear after 3 years. Self-harvesting.
Flowers pink. Recommended for both home garden and commercial
plantings.
Waimanalo
M. integrifolia. Originated at the Hawaii Agricultural Experiment
Station, Waimanalo, Hawaii. Large nuts, occasionally with twin
halves. Shell relatively thick. Kernel 38-1/2% of nut, flavor
good, oil content 75%. Tree medium-sized, pyramidal, productive,
begins to bear after 5 years. Produces nuts in large clusters.
Resistant to frost and disease. Grows well in cooler climates,
particularly near the ocean. Also yields good crops inland.
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