Pots and troughs show the way in the fight against bacterial wilt


Inside the 8 by 15m greenhouse in Kijauri, Kisii County, are tens of tomato plants growing in plastic bags.

A look at the crops gives one an impression that the owner, Abraham Makori, has planted them in the bags and he would then transplant them to the field later.

But that is not the case. Makori grows his tomato plants in the plastic bags to beat bacterial wilt, a deadly disease that widely affects the crop in many parts of the country.

Bacterial wilt attacks tomato plants causing them to start drying in less than five days. Once a section of the land is affected, the soil-borne disease will keep on attacking crops of the solanaceae family like potatoes, capsicum and eggplant planted on the portion.

Makori started his tomato venture in 2013 by planting the crop in a greenhouse.

“My tomatoes did well in the first season though there were a few cases of wilting and dying. I earned over Sh80,000 but when I planted the second time, I got less than half the harvest because the tomatoes were affected by bacterial wilt.”

Devastated, the farmer sought help from a colleague, who introduced him to a horticultural firm named Hortipro Ltd.

“The firm’s agronomists informed me that what I needed were the plastic bags, also called pots. I bought 700 pots at a cost of Sh17 each and planted 650 tomatoes in the greenhouse,” Makori, who embraced the method in August, says.

The method of farming involves the use of polythene pots measuring about 12 inches in diameter and 16 inches in height to grow the tomatoes.

Water that has boiled to 1000C is then poured evenly into the soil placed in the pots and allowed to seep through. This kills the bacteria, thus, greatly reducing chances of bacterial wilt attacking the crop.


Alternatively, one can burn the soil to kill the pathogens.

“The soil used in the pots should be collected from any part of the farm but preferably where it has been fallow for some period. The portion should not have had solanaceae crops grown on it,” explains Makori.

One adds approximately 500g of well-dried manure and mixes well with the soil before sterilising. “Chicken manure is preferred but it should be completely dry to reduce chances of harbouring any harmful bacteria,” says Makori, noting that tomato seeds are first planted in a nursery before being transferred to the polythene pots in the greenhouse.

The farmer is expecting a bumper harvest this season as he has lost few seedlings.

Wilfred Mokua, a greenhouse consultant with Hortipro Ltd, says the soil should be sterilised in the pots before planting tomatoes to control the bacterial wilt.

“The cheapest method of sterilisation is through the use of hot water, which is equivalent to moist-steaming.”

Makoris tomatoes are about three-and-a-half months now and they have started producing fruits. The technique has also allowed him to grow 150 more tomatoes than when he planted them on the ground in the same greenhouse.

He says that potting reduces competition for nutrients because each pot caters for a single seedling.

In Nyakoe, a few kilometres from Kisii town, Daniel Omwansa and his wife, Dorcas, are working alongside a few contracted workers in their newly constructed greenhouse measuring 16 by 30m.

“Our greenhouse will accommodate over 2,000 tomatoes but we have already planted only 1,000 seedlings in the pots,” says Omwansa, who has embraced the method after tomato crops he had grown with members of his church were destroyed by the bacterial wilt.

Although the method of farming is costly as one has to buy the bags, he switched to the technique mainly to fight bacterial wilt and other soil borne diseases common in the region.

Dr Bernard Towett of Egerton University’s Department of Crops, Horticulture and Soils Department, notes that besides controlling spread of diseases in the greenhouse, potting helps reduce the amount of water used in raising the crops.

However, he cautions farmers against reusing the same soil in subsequent seasons.

“Always refill the pots with fresh soil at the beginning of each season for better results.” Other diseases that are likely to be controlled by potting are fusarium wilt and root-knot nematodes.


According to Kenya Plant Health Inspectorate Service (Kephis), bacterial wilt disease is endemic.

The source of the soil-borne disease include uncertified seeds, which make it spread faster.

The disease can stay in the soil for ages, making it difficult for farmers to grow any crops.

Another source of the disease is decomposed farm yard manure.

Infected plants should be uprooted along with tubers in the case of tomatoes and disposed in a more than two feet deep pit.

Studies have recommended the use of virgin soil to grow crops as best options in curbing the spread of the disease.