Fw: [AG] Dates

[Olin Miller]

----- Original Message ----- From: <archsoul@home.com>
> > Are all dates from Palms edible? <snip>

Following is the text portion of Cooperative Extension Pub. 8330, "Growing
and Processing Dates". Should answer all of your questions.   -Olin

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The University of Arizona. College of Agriculture. Tucson, Arizona 85721

Lowell F. True and Allan D. Boettcher,
Agricultural Extension Agents, Maricopa County

Dates have been grown since ancient times and are an important food source
in desert regions of North Africa and Southwest Asia. Dates were first
grown in America from seed imported by Jesuit missionaries. The first
commercial date garden was planted in 1912 and between 1920 and 1945, about
500 acres of commercial date palms were grown in Arizona. Summer rainfall
proved a serious hazard to commercial production in the Salt River Valley
and most of the palms have been destroyed or the acreage has been
subdivided for housing because of unprofitable operation. Many of the palms
remaining at homesites are productive and property owners can harvest the
fruit. Because the date palm grows only in the desert, it commands a great
deal of local public interest.

Varieties

Dates may be classed as soft, semi-dry or dry {bread) dates. Soft dates
have soft flesh, high moisture content, low sugar content and are highly
perishable. Conversely, semi-dry varieties have firm flesh, low moisture
content, high sugar content and may be kept for weeks or months at room
temperature with little deterioration. Dry dates have a high sugar content
but are undesirable for fresh consumption because of their hard, dry flesh.
The following soft and semi-dry varieties commonly are found growing around
Arizona homes:

Halawy -Soft, medium size; yellow, ripening mid-season to amber; rain
tolerant, but tends to shrivel.
Hayany -Soft, large size; dark red, ripening early to deep purple; highly
susceptible to rain damage, ferments easily.
Khadrawy -Soft, medium size; yellow, ripening early to amber; rain
tolerant, but tends to shrivel.
Khustawy -Soft, small size; yellow, ripening mid-season to light brown,
rain tolerant.
Maktoom -Soft, large size; yellow, ripening late to amber; somewhat rain
tolerant, but tends to shrivel.
Medjool -Semi-dry, large size; orange-yellow, ripening mid-season to
reddish-brown; rain tolerant. This variety currently is being planted most
widely in Arizona, thus offshoots are difficult to obtain.
Zahidi -Semi-dry, small size; bright yellow, ripening late to light brown;
rain tolerant.

Removing and Planting Offshoots

Date palms are dioecious, each tree being specifically male or female. When
date palms are propagated from seeds, about one-half will be males and the
females rarely resemble the parent. Propagation from an offshoot is the
best way to start a young palm capable of producing high quality fruit.
Since offshoots are not commonly available from retail nurseries, the best
source is from established trees in neighborhood yards.

Select for transplanting offshoots 10 to 12 inches in diameter and weighing
35 to 70 pounds. Since growth is poor in winter months, plant offshoots in
April or May to take advantage of the warm summer growth period. Remove the
lower leaves and tie the remaining 10 or 12 younger leaves together with
twine {not wire) to make offshoot removal easier. Remove the soil at the
base of the offshoot to expose the roots and locate the tough stalk-like
connection to the parent palm. If it is not connected to the parent plant
the "offshoot" is a seedling and not desirable as a transplant. A special
date palm chisel is required to sever the connection and to cut the roots
at the offshoot base. The chisel blade is a hardened steel plate 9 x 4 x 1
inches in size, ground sharp and welded to the end of a 48-inch steel rod
11/4 inches in diameter . Successful offshoot removal requires two persons,
one to hold the chisel, the other to drive it with a 16-pound hammer. After
separating offshoot from parent, prune the tied leaves about 36 inches
above the offshoot trunk. Wrap with wet burlap until ready to plant. The
offshoots that develop above the soil line will not have any roots and will
be more difficult to transplant satisfactorily.

Plant the offshoot in a prepared hole in the center of a basin five feet in
diameter and 10 inches
deep. Work the soil carefully around the base and roots while water is
running into the hole. Air pockets in the. soil beneath the offshoot can be
fatal. If more than one palm is to be planted, space them at least 30 feet
apart. Keep the soil moist around the offshoot for at least six weeks after
planting by running three inches of water into the basin every three to
eight days, depending on soil type and weather conditions. During the
remainder of the summer months, fill the basin slowly every two weeks.

Irrigation
Established date palms are capable of surviving long periods without
irrigation but respond to regular deep watering. To maintain maximum
growth, the soil should be thoroughly wetted to a depth of six to eight
feet once during the winter and spring followed by summer irrigations at
intervals of 20 to 25 days. It will take approximately 8 inches of water to
moisten the top 6 to 8 feet or 4 to 5 inches of water to wet the top 3 or 4
feet. Damage to ripening fruit by late summer rains and accompanying high
humidity is more severe if the palms have been recently irrigated. Best
fruit quality is obtained when the trees are under moderate moisture stress
during ripening. Desirable soil moisture conditions may be difficult to
maintain in the home yard where there are lawns and other plants requiring
scheduled irrigations.

Fertilization
Date palms have deep spreading root systems capable of foraging widely for
nutrients. Maximum growth and fruiting will continue for many years in a
moderately fertile soil without additional fertilization. Annual
application of barnyard manure is an excellent way to maintain the soil
fertility. Application of moderate amounts of commercial fertilizer is
advisable for soils known to be low in fertility.

Leaf Removal
About 100 leaves are required to support a normal date crop. Since about 20
new leaves are produced each year, no more than 20 should be removed at
anyone time. If there are fewer than 100 leaves on the palm, remove only
the dead leaves. The number of leaves can be estimated by counting the
number of tiers of leaves, moving in a slightly spiral direction from the
lowest to the highest, and multiplying by 13. It is advisable to cut spines
from the leaf midribs to prevent personal injury during pollinating and
harvesting operations.

Pollination
Since male flowers are borne on separate trees, hand pollination is
necessary to insure a good fruit set. Some male trees bloom as late as
January; some female trees as early as mid-February. Most male and female
trees normally will flower during March and April. Collect male flowers
within a few hours after the sheath (Figure 3) splits open, to prevent
pollen loss. Store in a cool place. For the first few weeks a newly opened
male flower can be hung upside down in a cool, airy area until needed. One
must prevent mold from attacking the moisture laden pollen. Before
pollinating, remove about 1/3 to 1/2 of the female flower strands from the
center of each flower cluster. Cut three or four strands of florets from
the male flower and place among the female flower strands within one to
three days after its sheath splits open. The pollen-bearing male florets
may be held in place by tying the female flower with twine (Figure 4),
using a slip knot which gradually will loosen as the fruit development
proceeds.

Fruit Thinning
If fruit is not thinned, palms tend to over-produce, causing fewer flowers
to develop the following year. An average palm tree with 100 leaves can
easily support seven to eight of the approximately 18 flower clusters that
may develop during its flowering period. When developing berries reach 1/4
to 1/2 inch diameter, adjust the fruit load accordingly, removing the
smallest clusters first.

Fruit size can be increased by removing at the same time fruit strands from
the center of the re-
maining clusters, individual berries from the strands or both. In general,
removal of 40% to 60% of the berries from the cluster will nearly double
the weight of the remaining fruit at harvest. Physiological damage to fruit
of some varieties may result from over-thinning. To prevent wind damage to
the fruit and breaking of long fruit arms, support the weight of heavy
clusters by tying each one to an adjacent leaf midrib.
Reducing Rain and Insect Injury
Rain and high humidity may cause physical damage to the fruit in the period
preceding ripening. When this happens, cracks appear in the fruit surface
through which fungi and bacteria may enter. Fermentation or souring of the
fruit rapidly follows. Fruit clusters can be protected with commercially
available date covers. These heavy waxed ripple kraft bags are placed
around clusters and tied tightly to the fruiting arms just before the fruit
begins to ripen. Cut off the excess length so that no more than three to
four inches of the bottom of the cluster is exposed. It is advisable to
raise the covers temporarily soon after a rain to allow free air
circulation. Butcher paper is a satisfactory substitute for commercial date
covers. People also have had success using bags made from porous cloth
material which permits good air circulation within the bag. For example,
sheer curtain material will work for date bags. The bottom may be enclosed
to prevent bird entry . Bugs nor-
mally enter the date through the stem end. Fruit clusters that are properly
thinned will normally not develop a bug problem.

Dried-fruit beetles,. bees, wasps and birds also can cause extensive injury
to ripening fruit. At present no EP A.registered pesticides are available
for the protection of dates against such hazards. Properly installed paper
date covers tend to reduce these kinds of losses, however .

Harvesting the Fruit
It is necessary to make several pickings during the ripening season, as all
the fruit on a cluster does not ripen uniformly. To avoid losses from
insects and micro-organisms, dates should be picked when they are only
partially ripened. The beginning of ripening is marked by the appearance of
translucent spots on the skin at or near the fruit tips, gradually
spreading over the entire fruit surface. At this stage the flesh is still
firm, but as ripening proceeds, it becomes soft and mushy (tree ripe). For
home processing, it is best to wait until the fruit is fully translucent to
tree-ripe before picking. Damaged, sour and fermented fruit at. tracts
insects and should be selectively removed from the clusters at each
picking.

Sorting and Cleaning
Sort the fruit carefully and discard all sour and fermented dates. Soft
dates should never be washed directly in water. A convenient method to
clean small lots is to spread the fruit on the surface of a moist turkish
towel held on a tray. Gently shake, roll and tumble the fruit to remove
adhering soil and debris. Rinse the towel frequently in clean water .

Ripening and Curing
Dates picked before they are fully ripe can be completely ripened by
heating at a temperature between 95° and 120° F. Heating is continued until
the fruit is cured (dehydrated) to the point where spoilage will not occur.
Tree-ripened fruit need only be cured.
Fresh tree-ripe, uncured dates contain 35% to 40% moisture; the flesh is
soft and mushy and the skin is mostly unwrinkled. They must be refrigerated
to prevent spoilage. Fully cured dates contain 25% to 28% moisture; the
flesh is rather firm and pliable and the skin is wrinkled like that of a
prune. The fruit keeps well at room temperature. Almost any method may be
used to heat the dates, but the most common are the kitchen oven method and
the solar heater method.
Kitchen oven method: Spread dates one layer deep on trays and place on oven
shelves. Ideally, tray bottoms should be perforated to allow air
circulation but cookie sheets may be used. If possible, insert a thin glass
or metal thermometer into one of the dates. Heat oven until the fruit
temperature reaches 120°F and then turn off the oven. When dates have
cooled to 100°F, turn on the oven
again. Inspect the fruit frequently and remove individuals that have
ripened and cured to the desired point. Repeat procedure as necessary.
If a thermometer is not available, modify the procedure as follows: Preheat
the oven to 200°F using the oven temperature dial, then turn it off. Place
the dates in the oven and leave them until it has cooled. If necessary,
repeat the process until fruit is cured to the desired point. It is
essential that the dates not be over-heated. Fruit temperatures above 155°F
will caramelize the sugar and produce sticky, syrupy dates with a scorched
flavor.
Solar heater method: The solar heater is a shallow rectangular wooden box
with a sloping glass or plastic cover that admits and traps the sun's heat.
The sides should be tight, with screened openings at each end for
ventilation. Soft dates should be placed one layer deep on trays and
stacked in the heater. Semi-dry dates may be placed two to three layers
deep on the trays. The stack of trays in the heater should be rotated
occasionally so that all fruit receives the same exposure. On extremely hot
days, some partial shade may be required to reduce the temperature in the
box. Because the temperature drops at night, ripening and curing may
require two to eight days, depending on the fruit and the temperature
conditions. Inspect and remove ripened and cured fruit daily.

High Heat Treatment
High heat treatment (sometimes called "pasteurization") kills insect eggs
and adults and some yeasts and bacteria. Many resistant micro-organisms
survive the heat, but further dehydration also results, so treated dates
usually keep well. Place the previously ripened and cured dates in a
pre-heated oven and raise the fruit temperature to 150°F. Maintain the heat
for 30 minutes, using a good thermometer if possible. Do not overheat.
Remove fruit from the oven and allow to cool.

Storage of Dates
If the fruit is dehydrated to 20% to 25% moisture, no further treatment is
necessary and it may be stored at room temperature in almost any kind of
container. Dates containing more than 32% moisture should be refrigerated.
Regardless of moisture content, dates may be stored indefinitely in a
freezer at 0°F. The appearance of small white sugar crystals under the skin
of fruit stored for long periods in a refrigerator is unappealing to the
eye but does not harm the fruit for eating purposes. Most sugar spotting
occurs in fruit with 24% to 33% moisture and can be minimized by storage at
a°F or lower.