Macadamia Nuts in Hawaii: History and Production - ctahr ...

Before using any herbicide, read the entire label
carefully and follow the directions exactly.
Animal grazing is not recommended because of
nut contamination by animal refuse.
Pest Control
Insects. Although in its indigenous area of
Australia the macadamia does have many economically
serious insect pests (44), Hawaii has
only a few that need to be attended to.
The larvae of the koa seed worm, Cryptophlebia
illepida (Butler), and those of the litchi fruit moth,
C. ombrodelta (Lower), feed upon the nut husks,
and, if the shells are soft, will bore through and
damage the kernel (52,53). C. illepida, an insect
native to Hawaii, is parasitized by several natural
enemies, whereas C. ombrodelta, being an immigrant
species, has only a few enemies. Since chemical
control of these insects is difficult and not
economically feasible, field sanitation and the
elimination of alternate hosts, such as acacia, are
recommended.
The southern green stink bug, Nezara viridula
(Linnaeus) (43), was a major pest in the 1960s,
but, with the introduction of several predators and
parasites, it has been brought under reasonable
control, and chemical control of this insect is not
recommended.
The red-banded thrips, Selenothrips rubrocinctus
(Giard), and the Hawaiian thrips, Taeniothrips
hawaiiensis (Morgan), periodically develop
into epidemic proportions. Damage to flowers
reduces yield substantially. Leaves may also be
damaged, causing yellowing. The insects do not
normally attack young nuts, but older nuts may be
spotted with the silvery dried excrement of thrips.
This damage is of no significance. Wettable malathion
can be applied at 2 to 4 pounds peracre orto
a drip-wet state in which spray quantity is difficult
to judge. With the emulsifiable concentrate, 1 to 2
pints per acre is allowed with no time limitation
on its use. However, since malathion is toxic to
honeybees, application should be made early in
the morning when bee activity is low. Phosalone
(Zolane), an organic phosphate insecticideacaricide,
has been registered in Hawaii for use in
mite and aphid control, and is applied at 4 to 8
pints per acre per year.
Other insects such as ants, beetles, mealybugs,
and scales are of minor economic importance.
Stored macadamia nuts, sometimes infested by
beetles, can be treated with methyl bromide when
necessary.
Mites. Two species of mites, the broad mite,
Polyphagotarsonemus latus (Banks), and the red
and black flat mite, Brevipalpus phoencis
(Geijskes), cause damage to flowers with some
symptomatic tanning of husks and leaves (21).
Wettable sulfur has been found to effectively control
the mites. One large grower has been applying
wettable sulfur at 10 pounds per acre by air and
ground once or twice a year during the flowering
season to reduce the buildup of the mite population.
Morestan miticide has been cleared for use in
macadamia a t the ra te of 1 to 8 pounds per acre.
Three applications per season may be made, up to
the day of harvest. Plictran 50W miticide was given
a supplemental label to meet a special need in
Hawaii to control broad mites affecting macadamia
nuts. Four to 6 ounces of Plictran 50W per
100 gallons of wa ter are used. It is applied as 200 to
400 gallons of spray mixture using conventional
spray equipment. The miticide should be applied
when the broad mites appear and repea ted as necessary.
The use restrictions on the label specifically
say not to apply more than 6 pounds of Plictran
50W per acre per season, or more than four applications
per season, and not to apply it within 14
days before harvest.
The mite predators Metaseiulus occidentalis
(Nesbitt) and Amblyseius cali/omicus (McGregor)
were released in two large orchards in 1978. As of
1982, these predators have not been recovered.
Diseases. Currently, only three economically
important diseases affect macadamia. These are
the two flower blights, caused by Botrytis cinerea
(25,26,38,39,84) and Phytophthora capsici (40),
and a root rot organism, Kretzschmaria clavus (34,
35,37), especially prevalent in and associated with
the wet areas of Hilo and Pahoa.
1. Botrytis cinerea is a blossom blight that establishes
itself only on senescent floral tissues
of macadamia; affected flowers do not develop
into mature fruits (Fig. 72). This disease
is especially prevalent in Hawaii during
the winter months, when the humidity
approaches 95 percent and the temperature
is between 61 ° and 72°F in the flowering
season.
2. Phytophthora capsici is especially prevalent
during a prolonged wet period. It is a water
mold fungus that infests the immature raceme
even before the floral structures are
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