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Introduction
African nightshades, also called mnavu, can be found throughout
East Africa. There are several species with black berries, but
the most popular are those with orange berries belonging to Solanum
villosum. This group of species is often erroneously referred
to as Solanum nigrum, a poisonous plant from Europe that
is not usually grown in Africa. African nightshades can grow
on a wide range of soil types but require regular rains or frequent
irrigation. It does not tolerate drought.
Seeds and Sowing
The soil in the nursery should be loosened and enriched with
decomposed manure. Seeds should be mixed with sand and/or ash
for uniform sowing. Sow the mixture thinly, either by broadcasting
or in rows, 15-20 cm apart and cover with a fine layer of soil.
After sowing, the bed should be mulched with tall grass or a
similar material to retain moisture. This mulch can be removed
once the plants are 3 cm. Transplant when seedlings have 6 true
leaves and are 10-15 cm tall. The spacing should be 20 cm in
the row by 40 cm between the rows.
Crop Management
Nightshades require large amounts of nutrients, and therefore
do well in soils that are rich in organic matter. They also grow
well on land covered with ash from recently burned vegetation.
Farmers generally use 20-10-10 NPK, urea, or sulphate of ammonia
when there is no manure available. Sidedressing is practiced
after every second harvest. However, excessive applications of
nitrogen can lead to foliar diseases as well as a build-up of
nitrites, which could become a human health risk.
Frequent irrigation is needed
for good yields. Aphids are a major pest, causing leaves to curl
and become unattractive to customers. Diseases are similar to
those of potatoes and tomatoes, thus rotating with other crops
like amaranth is essential. In areas with a high humidity, wider
plant spacing should be used.
Harvesting
and Postharvest
The first harvest will be 5 weeks after transplanting. The stems
can be cut about 10 cm from the ground, so that new side shoots
develop. Pickings at roughly 7-14 day intervals will allow 3-4
harvests per plant (more if plants are sidedressed). If complete
harvesting is practiced, spacing can be as close as 10x10 cm
and plants are uprooted. This method is mainly used when there
is less than 2 months before the main staple-food crop will be
planted. Roots of these crops can be kept in water to keep the
plants fresh.
Picking should be done very early
in the morning and the produce sold the same day. Alternatively,
the crop can be harvested late in the afternoon and placed on
plastic sheets or banana leaves. These should be tied in small
bundles. The flowers should be removed before the crop is taken
to market. Water these bundles sparingly to retain freshness. |
