Cassava disease: How early detection can boost food security

Penultimate week, the Ministry of Agriculture and Rural Development, at the 2019 Cassava Investment Forum in Abuja, raised the alarm over a recent virile cassava disease, Cassava Brown Streak Disease (CBSD), ravaging East and Central Africa, which it said is now making its way to West Africa.

According to the ministry, “the disease has caused over 90 per cent loss in a cassava farm in the country.” The ministry, therefore, called for a collective effort in securing Nigeria and the West African region against the virus.

However, in a chat with the Senior Research Supervisor, Cassava Breeding Unit, International Institute of Tropical Agriculture (IITA), Ibadan, Ibrahim Sadeeq, Daily Sun learnt that the cassava disease, CBSD, may not have got to Nigeria yet as the institute has not received any report from any part of the country on any infected cassava farm.

Sadeeq who stated that officials of the institute are currently on inspection tour of cassava farms across the country, said no such situation has been noticed in any cassava farm.

He explained that, “if there’s any part of this country that cassava farms have been affected, IITA is supposed to have known. We do research on cassava and up till now, nothing has been seen and nobody has reported such a thing here. If they had reported, we would have gone there and seen what is happening there. We have not heard anything about it.

“IITA generally is not aware of it. We are working on cassava and we have cassava stations everywhere in the country. We are researchers working on cassava and we’ve gone round the country this year and we’ve not seen anything like that. Though we have been hearing about the disease but it is not pronounced in this country; it has not gotten to Nigeria yet.”

He, however, advised cassava farmers to vigilantly watch their farms for signs of the disease, which, he said, manifests in the cassava leaves dropping, looking discoloured and unhealthy.

To ensure that CBSD does not make inroad into cassava farms in the country, the IITA researcher, Sadeeq, urged Nigeria’s cassava farmers to source improved varieties of cassava stems from the institute, which he assured are disease resistant and high yielding. According to him, some of the varieties are yielding between 25 and 30 tonnes per hectare.

In a recent document on Cassava Virus Disease Surveillance in Nigeria, Dr. Lava Kumar, Head, Germplasm Health Unit/Virology, IITA, x-rayed prevalent cassava pests and diseases in many sub-Saharan African countries that have had high destructive effects on yield and quality of the crop as well as the impact of these on their economies.

Kumar noted that Cassava Mosaic Disease (CMD) and CBSD have been the major culprits threatening the food security of these countries as cassava forms a major food staple and income earner for most of them, especially Nigeria. He said, “

According to the document, CMD, which occurs in all the cassava production zones of the continent “can cause as much as 100 per cent yield loss in susceptible varieties” while CBSD “has demonstrated…potential to decimate cassava.”

“CMD infection results in mosaic, deformed shoot growth, and severely reduced tuberous roots. CBSD produces feathery vein-associated chlorosis and/or chlorotic blotching on the lower leaves of affected plants, but also a dry corky necrosis and extensive rotting of the tuberous roots making them inedible and unmarketable, leading to total loss of the useful part of the cassava.

“Recent outbreaks of CBSD in East Africa caused enormous human suffering due to the severe shortage of edible roots and disease-free planting material necessary for replanting, affecting the livelihoods of cassava growers and the cassava value chain,” the document said.

The disease is spread by whitefly and also through accidental use of infected stems for cassava propagation.

The report stated that, “ongoing measures to improve the cassava-based economy are wholly dependent on managing the various threats known to hamper cassava production and productivity. The consequences of an outbreak of CBSD in Nigeria would be catastrophic, as it would negate all of the positive gains achieved through the ATA (Agricultural Transformation Agenda) and negatively impact the food security and economy of millions of cassava farmers.

“To counter this threat, it is necessary to develop/strengthen early warning systems to facilitate the rapid detection, diagnosis and communication of cases of disease incursion, and to develop an emergency response plan for CBSD.”

On the need to develop a CBSD control strategy for the country, the document submits that early detection is important to prevent the emergence and establishment of new pathogens, adding that, “traditional methods involving regular surveys by experts are expensive and time-consuming. The recent revolution in digital communications technology has enabled the development of virtual networks for rapid communication and diagnosis of local problems from distance.”

It equally stressed the need to train extension services providers in major cassava-producing states for real-time monitoring and rapid communication on the disease situation and the implementation of mitigation plans; on disease recognition, the use of mobile phones for communication with NAQS Post-entry Quarantine Station in Ibadan (which will act as the coordinator for this early warning network) and the development of an action plan for emergency response.