Page 13 - Vol.37-No.8

CROP PROTECTION

day intervals using a recommended additionally made into jams, juices and
and approved fungicide. Insect pest pickles (base for pepper sauce) in local
problems include aphids, mites and cottage industries. Large numbers are
fruit flies. sent for commercial processing includ-
Plants start to flower 6 months after ing canning, juicing and jam making.
planting with first fruit maturing some The often neutral and bland taste of
4 months later. During the next 18 to papaya is improved during processing
24 months, growers can expect at least by addition of passion fruit juice. The
100 fruits. After two-years of fruit pro- fruit is considered to be a mild laxative
duction papaya plants may be cut down and the seeds are used medicinally
to re-sprout, although this practice is against worms (helminths).
not generally used by commercial
holdings which prefer to replant with
Ripe fruit will frequently show the new stock.
characteristic dark sunken lesions of
anthracnose disease especially if they For local consumption fruits are
were not protected by regular sprays picked when the skin is yellow half
of fungicide in the field way up the fruit, but earlier for export
(Picture Dr Terry Mabbett) and when the blossom-end of the fruit
just begins to turn colour. Either way,
the filling soil is mixed with organic pickers must wear gloves and take care
manure, phosphate fertiliser and lime- because the acrid latex which flows
stone before filling in around the roots. from the cut will irritate and damage Flesh of ripe papaya fruit is orange/
human skin as well as staining and
A balanced NPK compound fertiliser spoiling the fruit. Fruit are picked by red or yellow depending on the variety
(15:15:15) is applied three times during cutting the stalk with a thin-bladed (Picture Dr Terry Mabbett)
the first year after which fertilizer appli- knife and laid gently in single layers
cation is switched to a mixture higher on corrugated cardboard and covered Papain is widely used in the brewing
in potassium with some magnesium/ with low density polythene film. industry to produce chill-proof beer.
calcium and trace elements. Papaya The papain prevents coagulation and
with its fast growth rate requires al- Papaya fruit ripen in just two to three precipitation of proteins, and therefore
most constant fertilisation, but nitrogen days when held at temperatures be- cloudiness in beer, at low temperature.
fertilisers should be applied with care tween +12.8 to +18.5°C. Papaya which It is also used in the food industry as a
as processors will reject fruit with high is less than half ripe must not be stored meat tenderiser. Some tropical com-
nitrate content. at temperatures below +7 °C because munities use bruised papaya leaves to
such temperatures will curtail the rip-
Plants should be kept free of weeds ening process. As such the optimal stor- wrap up ‘tough’ meat from backyard
ideally by mulching with dead plant age temperature is generally given as or common fowl the day before it is
material or black polythene. Or by sow- +7°C for fruit which are already ripe cooked.
ing living cover crops like Centrosema or ‘turning, and +10°C for green fruits, Papain is used in the manufacture of
and Pueraria in the wet tropics. All these if chilling is to be avoided. At these chewing gum, in the leather industry
options are preferable to mechanical temperatures, green papayas have to treat hides and in the textile indus-
weeding which can damage the papaya a PSL (Potential Storage Life) of 3-4 try to prevent the shrinkage of silk. In
stems and feeder roots. weeks, and ‘turning’ papayas a PSL toothpaste to prevent pyorrhoea, which
Seedling rot caused by the fun- of 2-3 weeks. Once the fruit is ripe is the shrinkage of gums caused by
gus-like Phytopthora pathogen is man- it can be refrigerated. Refrigeration the build-up of bacterial plaque on
aged through good drainage and san- slows down the ripening process and the teeth, and in medicines as a mild
itation, including removal of debris prevents the fruit from becoming over- laxative.
and infected seedlings. Anthracnose ripe prematurely. Ripe papaya should
disease caused by Colletotrichum gloe- keep its quality for about 5 to 7 days
osporioides, and responsible for dark, when under refrigeration.
depressed and unsightly lesions on the The latex is unpleasant, but the chem-
mature and ripening fruit, is controlled ical constituent called papain has uses
by spraying the fruit and foliage at ten- of its own. Papain is widely used in
industry and is harvested as a com-
mercial crop by tapping the green fruits
for their latex. Tapping starts when im-
mature fruits are 10 cm wide and by
making 3-4 vertical cuts, 3 mm deep Central cavity of the papaya fruit
using a razor blade secured to a stick. contains an abundance of round,
Latex is caught and gathered in trays dark-coloured seed
fixed to the stem and is subsequently (Picture Dr Terry Mabbett)
coagulated in the sun or in an oven at
+55°C. Tapping continues weekly by India tops the world table for the pro-
A large papaya fruit purchased at a making new cuts between the old ones. duction of papaya fruit with 6 million
retail outlet in the United Kingdom and Latex yields are approximately100 kg/ tons. Brazil and Mexico are in second
weighing in at 1.2 kg. However, smaller ha/year. Tapped fruits are clearly not and third positions with around 1.0 mil-
and more compact varieties of fruit suitable for export, but can be eaten lion tonnes each. Brazil and Mexico are
have become an increasing feature of locally or sent for processing. the top exporters of papaya fruit, with
today’s global export trade in papaya Fresh papaya is popular as a break- United States, Germany and Canada as
(Picture Dr Terry Mabbett) top importing countries in that order.
fast fruit throughout the tropics and is
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