Farmers in Nyamagabe District have decried the rate at which pests are destroying their crops.

The infestation that has pests eating away the roots of their crops or eroding their tubers is that of white grubs (locally known as ‘Ibishorobwa’).

Farmers say the affected tubers have a bitter taste and turn dark in colour.

"Since the insects appeared in our fields we cannot harvest sweet potatoes or beans. The tubers get bitter so we give them to cows as forage. The roots of beans are eaten by the pests and they fall off before flowering,” said Philomène Bushyikiro, from Kitabi Sector in Nyamagabe District.

Justin Karemangingo, 71, another resident of Kitabi, said the pests have left him counting losses and threatening food security. Irish potatoes, sweet potatoes, beans and peas are the most prone to the attacks because of their relatively weak roots.

The farmers asked for timely interventions to enable them contain the pests.

Nyamagabe District agronomist Donatha Mukamuganga said the insects began to appear in 2013. She said they initially attacked crops in Kibirizi and Tare sectors but have also started to appear in other parts of the district.

Nematode intervention

Normally, there are nematodes that are considered enemy of crops because they attack them and have adverse effects on productivity.

However, from 2014, Rwanda Agriculture Board (RAB) started a biological soil pest control project consisting of producing beneficial nematodes as control agents, which kill and eat the pests in the soil.

According to RAB officials, the beneficial nematodes are produced artificially in vitro through the use of soya, wheat, maize and yeast, egg yolk mixed with small mattress sponge pieces as substrate.

After the nematodes are produced, they are applied in fields or kept in a cool room where they can live up to six months.

One cone flask could produce seven to 10 million nematodes when about 6,000 nematodes were inoculated into it.

Joelle Kajuga, the in-charge of research at RAB southern zone and the coordinator of the project, said because nematodes have different features, research is still being done to identify the most efficient and powerful nematode that would be multiplied and availed to farmers for use in fields.

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