In Summary
  • One can apply yeast mixed in lukewarm water and spray the solution on tomato leaves once every two weeks.

Tomato farmers in east Africa can control pests such as aphids, whiteflies, thrips, and diseases such as blight without use of pesticides by using a number of organic control measures that are harmless to the environment and humans. The World Health Organisation (WHO) and the United Nations Environment Programme (UNEP) estimate pesticide poisoning rates in the farm at two to three people per minute.

How to mix
In this, one can apply yeast mixed in lukewarm water and spray the solution on tomato leaves once every two weeks.
Alternatively, make ash from dry pawpaw leaves then mix with water (one kilogramme per 20 litres of water) and spray the suspension onto your tomato crop.

According to a 2015 research by Moses Njeru of Chuka University published in the International Journal of Humanities and Social Sciences on challenges and benefits of organic farming among farmers in Nembure division, Embu County, more than 83 per cent of farmers recorded increased farm production since adopting organic farming. Out of these 76 per cent attributed the increase in farm input to adoption of organic farming techniques such as use of compost manure, use of plant teas for top dressing and intensification of tillage practices (double dug beds and sausage gardens).
Twenty four per cent of those who had an increase in farm input attributed it to their use of organic fertilisation techniques.

The diseases
Diseases that attack tomatoes 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.

In order to manage these diseases, fungicides are sprayed. The most common fungicide used in East Africa is Mancozeb (Dithane M45).However, copper fungicides are also used. Fungicides are not very toxic.
Tomato has very many insect pests that cause damage, including 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.