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Mubuku scheme farmers decry pesticide-resistant armyworm

Farmers in Mubuku irrigation and settlement scheme are battling the fall armyworms ravaging vast gardens of maize. This, coupled with poor management of water for irrigation, has triggered a water crisis, writes ARTHUR MATSIKO.

Jonathan Byaruhanga has been smiling as he walks me through his mixed farm of onions, beans, maize, rice and oranges.

We are being followed by a group of farmers and officials from government and Food and Agriculture Organisation (FAO). Stepping into his four-acre garden of maize, the 70-year-old’s face scowls at how crop-eating caterpillars known as fall armyworms are ruining his two-month-old maize.

Thomas Bahwere holds an armyworn that destroys his maize

After picking a live maggot-like insect from the top of a maize plant, he wobbles his grey-haired head, deliberating what to do next. Since 1970, Byaruhanga has been growing various crops here.

Amidst other challenges such as price fluctuations of farm produce, Byaruhanga’s prime crisis is the pesticide-resistant armyworms.

“Pests have continuously infested my maize gardens,” says Byaruhanga. “We have sprayed with various types of pesticides, but these insects are not dying.”

Among other affected farmers is Thomas Bahwere. Like Byarugaba, 65-year-old Bahwere is distressed by the destructive pest.

“I think responsible authorities should do something to help us deal with this armyworm; otherwise, we shall continue making losses,” Bahwere says.

Recently, the US Agency for International Development (USAID) offered a prize of Shs $150,000 (about Shs 556m) for the most viable solution to fall armyworms, two awards of $75,000 (about Shs 276 million) to the “most promising” solutions, and two awards of $50,000 (about Shs 185 million) to an “early stage” solution that shows the most potential.

The moths mainly attack maize, the staple food in about 300 million homes in Africa and, according to USAID, they attack 80 other types of crops including sorghum, cotton, rice and sugarcane.


Besides pests, most farmers on the 512 hectares have little knowledge about the value of each unit of water used in production on irrigated farms. Mubuku uses the furrow method of irrigation.

The design of Mubuku field ditches was supposed to use a maximum discharge of 30l/s (litres per second) of water per irrigation time. Following the destruction of the hydraulic properties of the field ditches, however, this discharge is no longer enough to raise the water level to irrigate the farmland.

According to the irrigation schedule, two farmers on adjacent holding are supposed to share water at the same irrigation time, splitting the discharge into two.

Because water is no longer enough to fill their field ditches, one farmer foregoes to irrigate and gives all the water to the neighbour who utilizes the whole discharge of at least 60l/s. Due to its high velocity on the furrows, 70 per cent of the water usually ends up in the drainage.

As a result of poor on-farm irrigation water management skills, farmers are using excess water per irrigation. But due to high velocity of water flow in the furrows, less water infiltrates the soil and is stored in the crop rooting zone.


Despite farmers using a lot of unnecessary water during irrigation, however, they still under irrigate. This challenge urged FAO to undertake activities with a few host farms to demonstrate how to improve crop water productivity and water use efficiency.  Thus, the project commenced in March 2016 with calibration of AquaCrop software for maize, rice and onions. 

Dennis Besigye, the project coordinator, told The Observer that through an agreement with the National Agricultural Research Organisation (NARO) and University of Cordoba, Spain, the project did a survey of the water conveyance system and the on-farm hydraulic structures from the tertiary canals, field ditches and furrows.

Various observations were made by the team from which recommendations to improve crop water productivity and increase water use efficiency were made.

“To address the issue of water levels on the farm, consultants recommended modification of the hydraulic properties of field ditches by reducing their depth and width to sizes of double ploughing to improve the water infiltration capacity of the soil of the demo farms,” Besigye adds.

Jonathan Byaruhanga demonstrates how furrow irrigation is done

FAO interventions have reduced water used on demo farms up to 70 per cent (from 60 l/s to about 15-20 l/s). To avoid water spilling over to the drainage, the irrigation period was determined using the “quarter time rule” – about 30 minutes of flow.

“Therefore, once water would be opened to flow in selected furrows, it would have covered about 90 per cent of the furrow in 30 minutes,” he says. “After this period, the water flow is cut to allow the recession phase to cover the remaining 10 per cent of the furrow.”

On his three-acre farm of onions, Byaruhanga is one of the many farmers who have adopted and implemented water use efficiency techniques. When we visited him, Byaruhanga was demonstrating to fellow farmers on how to efficiently use water for irrigation.

Mubuku farmers’ chairman, Michael Bagonza, urged them to transfer what had been demonstrated on host farms to individual farm holdings.

“We have water in River Sebwe, but complain it is not enough yet if used efficiently, it is more than what we need,” Byaruhanga says.

With water issues under control, fall armyworm remains a threat as farmers such as Byaruhanga and Bahwere continue counting losses.


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