Newsletter issue 33 - Nogamu

Organic Tomato
by: Dr Charles Ssekyewa
Tomato is one of the crops where pesticides
are frequently applied. The reasons for
spraying tomatoes with synthetic chemicals
are mainly are disease infections and insect
pest damage.
Diseases that attack tomato include
late blight which comes early during
vegetative stages of the tomato, and
early blight which comes at the stage
when tomatoes are aging.
Late blight is more destructive and is
favoured by misty dull weather with
high humidity.
The causal fungus can be transmitted
by wind as spores, and also in water as
zoospores (look like tadpoles) which
can swim. To manage these diseases,
fungicides are sprayed. The most
common fungicide used in Uganda is
Mancozeb (Dithane M45). However,
copper fungicides are also used.
Fungicides are not very toxic and their
minimum allowed dosage/concentration
(Minimum Residual Limit) is usually higher
than that for insecticides.
Tomato has very many insect pests that cause
damage to it. The most notorious insects are
aphids, whiteflies, thrips, African bollworm,
and in highlands green mites. The first three
transmit viruses in tomato, while the last two
simply cause economic damage to leaves and
fruits.Aphids and whiteflies are most prevalent
during the early vegetative growth stages of
the tomato.Thrips, African bollworm and mites
have high population during the dry season and at
mature/fruiting stage of the tomato.
Organic agriculture has more than non use of
synthetic chemicals, that aspect is the core and
major component of the organic concept. Other
aspects dealt with are best environment conservation
practices and respect of nature.This being the
understanding of organic agriculture, tomatoes can
be grown without use of synthetic chemicals and with
best conservation practices. The best time to grow
tomato organically is the wet season. During that time,
late blight is the major constraint. There are organic
fungal control measures can be applied t. some of
these are :
1- Apply yeast mixed
in lukewarm water.
Spray the solution
on leaves of your
tomatoes once
every two weeks.
2- Make ash of dry
pawpaw leaves,
mix with water
(1kg per 20ls of
water) and spray
the suspension
onto your tomato
crop.
3- Prune off diseased
leaves and stems
as soon as they are
seen
Note that such
tomatoes will have a
thin skin. To avoid this
problem which is true
for variety Heinz, grow
hard skin varieties such
as Money maker.
The writer is an has
in PhD in Biological
Sciences, from Ghent
University and
Associate Professor of
Agriculture. He is
Chairman UgoCert
Board,
Director of Research
at Uganda Martyrs
University,
Chairman Caritas
Kampala,
Member of Board, the
International Society
for Organic Research
(ISOFAR),
Member NOGAMU
Programs Committee.
Nogamu at Ten Years
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