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Re: germinating papaya (long)

I found this info at the Cal. Rare Fruit Growers site:

PAPAYA

Carica papaya L.

Caricaceae

Common Names: Papaya, Papaw or Paw Paw
(Australia), Mamao (Brazil), Tree Melon. 

Related Species: Babaco (Carica pentagona),
Mountain Papaya (C. pubescens), Chamburo (C.
stipulata). 

Origin: The papaya is believed to be native to southern
Mexico and neighboring Central America. It is now present in every tropical
and subtropical
country. 

Adaptation: Papayas have exacting climate requirements for vigorous growth
and fruit
production. They must have warmth throughout the year and will be damaged by
light frosts.
Brief exposure to 32° F is damaging and prolonged cold without overhead
sprinkling will kill the
plants. Cold, wet soil is almost always lethal. Cool temperatures will also
alter fruit flavor.
Papayas make excellent container and greenhouse specimens where soil
moisture and
temperature can be moderated. 

DESCRIPTION

Growth Habit: The papaya is a short-lived, fast-growing, woody, large herb
to 10 or 12 feet in
height. It generally branches only when injured. All parts contain latex.
The hollow green or deep
purple trunk is straight and cylindrical with prominent leaf scars. Its
diameter may be from 2 or
3 inches to over a foot at the base. 

Foliage: The leaves emerge directly from the upper part of the stem in a
spiral on nearly
horizontal petioles 1 to 3-1/2 feet long. The blade, deeply divided into 5
to 9 main segments,
varies from 1 to 2 feet in width, and has prominent yellowish ribs and
veins. The life of a leaf is 4
to 6 months. 

Flowers: The five-petalled flowers are fleshy, waxy and slightly fragrant.
Some plants bear only
short-stalked female flowers, or bisexual (perfect) flowers also on short
stalks, while others may
bear only male flowers, clustered on panicles 5 or 6 feet long. Some plants
may have both male
and female flowers. Others at certain seasons produce short-stalked male
flowers, at other times
perfect flowers. This change of sex may occur temporarily during high
temperatures in
midsummer. Male or bisexual plants may change completely to female plants
after being
beheaded. Certain varieties have a propensity for producing certain types of
flowers. For
example, the Solo variety has flowers of both sexes 66% of the time, so two
out of three plants
will produce fruit, even if planted singly. How pollination takes place in
papayas is not known
with certainty. Wind is probably the main agent, as the pollen is light and
abundant, but thrips and
moths may assist. Hand pollination is sometimes necessary to get a proper
fruit set. 

Fruit: There are two types of papayas, Hawaiian and Mexican. The Hawaiian
varieties are the
papayas commonly found in supermarkets. These pear-shaped fruit generally
weigh about
1 pound and have yellow skin when ripe. The flesh is bright orange or
pinkish, depending on
variety, with small black seeds clustered in the center. Hawaiian papayas
are easier to harvest
because the plants seldom grow taller than 8 feet. Mexican papayas are much
larger the the
Hawaiian types and may weigh up to 10 pounds and be more than 15 inches
long. The flesh may
be yellow, orange or pink. The flavor is less intense than that the Hawaiian
papaya but still is
delicious and extremely enjoyable. They are slightly easier to grow than
Hawaiian papayas. A
properly ripened papaya is juicy, sweetish and somewhat like a cantaloupe in
flavor, although
musky in some types. The fruit (and leaves) contain papain which helps
digestion and is used to
tenderize meat. The edible seeds have a spicy flavor somewhat reminiscent of
black pepper. 

CULTURE

Location: Papayas like to be warm with both sunshine and reflected heat, so
the hottest place
against the house where nothing else seems happy is an ideal location. They
also like to be as free
from wind as possible, although this is not as critical as their need for
sun. Papayas can be grown
successfully in shade, but the fruit is rarely sweet. They are best planted
in mounds or against the
foundation of a building where water can be controlled. 

Soils: Papayas need a light, well-drained soil. They are easily killed by
excess moisture. The soil
needs to be moist in hot weather and dry in cold weather. Since this is the
opposite of California's
rain pattern, in addition to good drainage, plastic coverings to prevent
over-wetting in winter may
also be worthwhile. Papayas do not tolerate salty water or soil. 

Irrigation: Watering is the most critical aspect in raising papayas. The
plants should be kept on
to the dry side to avoid root rot, but also need enough water to support
their large leaves. In
winter the plant prefers to remain as dry as possible. A plant that has been
injured by frost is
particularly susceptible to root rot. 

Fertilization: The fast-growing papaya requires regular applications of
nitrogen fertilizers but the
exact rates have not been established. Feed monthly and adjust according to
the plant's response.
They can take fairly hot organic fertilizing such as chicken manure if used
with deep irrigation after
warm weather has started. Phosphorus deficiency casuses dark green foliage
with a
reddish-purple discoloration of leaf veins and stalks. 

Pruning: Papayas do not need to be pruned, but some growers pinch the
seedlings or cut back
established plants to encourage multiple trunks. 

Frost Protection: Papayas need warmth and a frost-free environment, but can
often withstand
light freezes with some kind of overhead protection. This can be provided by
building a frame
around the plants and covering it with bedding, plastic sheeting, etc. when
frost threatens. Electric
light bulbs can also be used for added warmth. Potted specimens can be moved
to a frost-secure
area. Prolonged cold, even if it does not freeze, may adversely affect the
plants and the fruit.
Mexican papayas are more hardy than Hawaiian varieties. 

Propagation: Papayas are normally propagated by seed. To start a plant,
extract the seeds from
ripe papayas and wash them to remove the gelatinous covering. They are then
dried, dusted with
a fungicide and planted as soon as possible (the seeds loose their viability
rapidly in storage).
Plant the seeds in warm (80° F), sterile potting mix. Seeds should be
planted in sterile soil as
young papaya seedlings have a high mortality rate from damping off. Potting
soil can be sterilized
by mixing 50-50 with vermiculite and placing in an oven at 200° F for one
hour. Under ideal
conditions the seeds may germinate in about two weeks, but may take three to
five weeks.
Gibberellic acid can be used to speed up germination in some seasons.
Seedlings usually begin
flowering 9 - 12 months after they germinate. 

Seedling papayas do not transplant well. Plant them in large containers so
the seedlings will have
to be transplanted only once, when they go into the ground. Transplant
carefully, making sure not
to damage the root ball. To prevent damping off, drench the potting mix with
a fungicide
containing benomyl or captan. Set the plants a little high to allow for
settling. A plastic mulch will
help keep the soil warm and dry in wet winter areas, but remove it as soon
as the weather
becomes warm. Plant at least three or four plants to insure yourself of
having females or plant
hermaphroditic plants. 

Papaya plants can also be grown from cuttings, which should be hardened off
for a few days and
then propped up with the tip touching moist, fertile soil until roots form.
Semihardwood cuttings
planted during the summer root rapidly and should fruit the following year. 

Pests and diseases: Thrips, mites and white flies as well as In red spider
and fruit spotting bugs
are potential problems in some areas. The plants may also be attacked by
mildew, anthracnose,
root rot and various virus diseases Fruit flies often ruin the fruit in
Florida and Hawaii. Nematodes
can attack the roots and are often a factor in the decline of individual
plant. Gopher damage can
be avoided by planting in wire baskets. Papaya plants should probably be
replaced every 4 years
or so. 

Harvest: Papayas are ready to harvest when most of the skin is yellow-green.
After several
days of ripening at room temperature, they will be almost fully yellow and
slightly soft to the
touch. Dark green fruit will not ripen properly off the tree, even though it
may turn yellow on the
outside. Mature fruit can be stored at 45° F for about 3 weeks. Papayas are
often sliced and
eaten by themselves or served with a myriad of other foods. They can also be
cooked to make
chutney or various desserts. Green papayas should not be eaten raw because
of the latex they
contain, although they are frequently boiled and eaten as a vegetable. In
the West Indies, young
leaves are cooked and eaten like spinach. In India, seeds are sometimes used
as an adulterant in
whole black pepper. 

CULTIVARS

Kamiya
     A selection from Waimanalo. Solo type. Small to medium-sized fruit.
Distinct, blocky
     shape, very short neck. Deep yellow-orange skin and flesh, firm, juicy,
very sweet. Dwarf,
     high-yielding plant. Fairly recent release from the University of Hawaii. 
Mexican Red
     A rose-fleshed papaya that is lighter in flavor than Mexican Yellow.
Medium to very large
     fruit. Generally not as sweet as Hawaiian types 
Mexican Yellow
     A very sweet and flavorful, yellow-fleshed papaya. Medium to large
fruit, can grow up to
     10 pounds. Generally not as sweet as Hawaiian types. 
Solo
     Fruit round and shallowly furrowed in female plants, pear-shaped in
bisexual plants.
     Weight 1.1 to 2.2 pounds. Skin smooth, flesh firm, reddish-orange, very
sweet, of
     excellent quality. Produces no male plants, only bisexual and female in
a 2 to 1 ratio.
     Introduced into Hawaii from Barbados in 1911. Named Solo in 1919. 
Sunrise (Sunrise Solo)
     Pear-shaped fruit with a slight neck. Averages 22 to 26 ounces
depending on location.
     Skin smooth, flesh firm, reddish-orange, sweet, sugar content high.
Quality similar to Solo.
     Seed cavity not as deeply indented as other Solo strains, making seed
removal easier.
     Plant precocious, maturing fruit about 9 months after transplanting, at
a height of about
     3 feet. 
Sunset (Sunset Solo)
     Solo type. Small to medium-sized, pear-shaped fruit. Orange-red skin
and flesh. Very
     sweet. Dwarf, high yielding plant. Originated at the University of Hawaii. 
Vista Solo
     Medium to large fruit depending on climate, 5 inches wide, up to 18
inches long. Skin
     yellow, flesh orange to yellow-orange. Hardy, compact Solo type
producing high quality
     fruit. Needs fairly hot weather to develop sweetness. Self-fertile.
Originated in Vista, Calif.
     by Ralph Corwin. 
Waimanalo (Waimanalo Solo, X-77)
     Fruit round with a short neck, average weight 16 to 39 ounces. Skin
smooth, and glossy,
     cavity star-shaped. Flesh thick, firm, orange-yellow in color, flavor
and quality high, keeps
     well. Recommended for fresh market and processing. Fruits of female
plants rough in
     appearance. Average height to the first flower is 32 inches. 

FURTHER READING

     Maxwell, Lewis S. and Betty M. Maxwell. Florida Fruit. Lewis S.
Maxwell, Publisher.
     1984. pp. 21.. 
     Morton, Julia F. Fruits of Warm Climates. Creative Resources Systems,
Inc. 1987. pp.
     336-346. 
     Ortho Books. All About Citrus and Subtropical Fruits. Chevron Chemical
Co. 1985.
     pp. 64-66. 
     Popenoe, Wilson. Manual of Tropical and Subtropical Fruits. Hafner
Press. 1974.
     Facsimile of the 1920 edition. pp. 225-240. 
     Samson, J. A. Tropical Fruits. 2nd ed. Longman Scientific and
Technical. 1986. pp.
     256-269. 

See Index of CRFG Publications, 1969 - 1989 and annual indexes of Fruit
Gardener for
additional articles on the papaya. 

Here is the list of additional CRFG Fruit Facts. 

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