With increasing demand for tomatoes, on the local and export markets, there is a growth of commercial tomato growing. Because of this, the vegetable has become a cash crop for many farmers in Uganda.
But several of them are experiencing losses because they lack the knowledge on the best practices for growing the crop.
For high and best quality tomato yields, agricultural experts and prominent farmers advise farmers to do the following.
Nassib Mugwanya, a graduate Research Assistant at School of Agricultural Sciences, Makerere University, says tomatoes grow best in soil that is just slightly acidic with a pH level of 6.0 to 7.0; but soil pH can be adjusted if needed. If it is too high, mix some sulfur into the soil. If the pH is too low, add lime.
Soil pH is a measure of soil acidity or alkalinity. On the pH scale, 7.0 is neutral, so the range, which tomatoes prefer is slightly on the acid side.
For commercial tomato farmers, they can contact extension workers to measure the soil pH and provide appropriate advice.
Patrick Mukalazi, a commercial tomato grower in Bwetyaba village, Kayunga District, with a 10-year experience in growing the vegetable, points out that that apart from the soil pH, tomatoes can do well in a wide range of soils, as long as they are fertile and well-drained.
In case the soil is not fertile, compost manure, cow dung and chicken droppings can be added to raise its fertility.
The cow dung should be dried while compost manure should be fully decomposed before being mixed with the soil, where tomatoes are to be planted.
Since tomatoes have small roots, a farmer should work the soil until it is loose to a depth of six to eight inches. This will allow the roots to grow quickly. Loosening the soil can be done with a hoe, tiller or tractor.
After the soil has been well tilled and is loose, a farmer can dig holes where he/she will plant the tomatoes. The holes should be dug one and half feet from each other.
In the holes, a farmer can put organic or compost manure or chicken droppings so that when the seedlings are transplanted from the nursery bed to the main garden, the manure is ready.
Likewise, Mukalazi says a farmer can apply the fertiliser (chemical) on the plants a week after transplanting them.
He, however, advises that if a farmer uses the former method, the seedling should be planted some inches away from the manure. Planting directly into where the manure is placed affects the seedling by making it wither.
Types of fertilisers to be applied on tomatoes
DAP fertiliser or Boost should be sprayed on seedlings soon after, to make them strong and healthy.
DI grow (green) should also applied on the tomatoes to boost growth of the plant. Mukalazi explains that the dosage to be applied depends on the health of crops.
He stresses that insecticide and fertilisers should not be applied at the same time as insecticides weaken the strength of fertiliser.
DI grow (red) fertiliser should be applied when the fruits are mature to prevent the fruits from perishing fast.
Pests and diseases
Leaf spot is one of the common tomato plant leaf diseases. Small black spots may show up in the centre of the leaf and affected plant leaves turn yellow, wither and then fall off.
This disease is caused by long periods of warm and wet weather. To control the disease, spray the tomato plants with Dythene as this will make the leaves healthy.
Another is the tomato blight disease caused by a fungus. Its symptoms include dark brown/blackish round patches on leaves and stems. The disease can also affect the fruit, which may develop dark markings.
Affected plants should be sprayed with fungicides. A farmer should avoid spraying his/her tomatoes during flowering stage with concentrated insecticides as this will either kill or scare away the bees and other insects crucial in pollination processes.
If pollination does not take place, the fruiting may not happen. Even then the unconcentrated insecticides should be applied only twice a month to give time for insects to carry out pollination.
A farmer is advised to have large containers or tarpaulin where he or she will place the fruits. If tomatoes are put in small containers after being harvested, they may be affected by the heat between them when they are placed close together. They should be kept under shade where rain or sunshine will not affect them.
Additionally, a farmer is advised to cut his or her nails while harvesting as the long nails can damage the tomatoes, which lowers their shelf life.
Tomatoes should be harvested when the dew on them has dried otherwise those harvested with dew perish fast when stored. The harvest should be done three days after spraying them with Dythene insecticide as this helps to increase their shelf life.
Mr Mukalazi says the lucrative market is usually in March since there is usually a long drought in December, which affects or hinders planting of tomatoes. Because of the long drought, those who can irrigate their crop earn a lot of profits due to a limited supply on the market.
There is a big local market and also in export to outside markets in Kenya, Sout Sudan and Europe, where they fetch a lot of money.