Long dry season, diseases affect cassava production in Lango

Wednesday March 30 2016

By Peter Wamboga-Mugirya

Cassava farmers and processors in Lango region are suffering a double challenge of sustainably raising quantities of fresh tubers for sale and for industrial processing into products like flour, ethanol and alcohol due to adverse weather and disease infestation.
They say an upsurge in the cassava brown streak disease (CBSD) during the prolonged dry season, has had serious impact, according to a recent survey and interaction with cassava farmers in the region.
The population of whiteflies that transmit the Cassava Brown Streak Virus (CBSV) causing CBSD, has increased tremendously in this dry season.
Frederick Doi, a cassava farmer and until recently a worker at Ngetta Zonal Agricultural Research and Development Institute (Zardi), revealed that all districts that comprise Lango: Lira, Oyam, Dokolo, Kole, Alebtong, Amolatar and Otuke, are a vast epicentre of the whitefly-infestation and CBSD-spread in most cassava plantations.
The Roots Crops’ Programme at NaCRRI, Namulonge, which is carrying out research on CBSD, confirms there is continuous presence of the whitefly and the virus throughout the year.
CBSD infects all cassava varieties especially those to which farmers have strong attachment, says Henry Wagaba, a scientist on the Virus Resistant Cassava for Africa (VIRCA) project, which is also based at NaCRRI.
It is working on ways to control CBSD and Cassava Mosaic Disease (CMD).

Scale-down in harvests
Information from VIRCA shows there are four viruses that cause CBSD and CMD in East Africa, including Uganda. These are: East African Cassava Mosaic-Uganda (EACMV-UG), the African Cassava Mosaic Virus (ACMV), Uganda Cassava Brown Streak Virus (UCBSV) and CBSV.
The project confirms that Uganda is experiencing a CBS-disease severity, incidence, high virus incidence and big whitefly population.
CMD continues to threaten cassava production in the Lake Victoria and Lake Kyoga sub-regions, reducing yields by as much as 80 per cent, causing a more than $30m (Shs75b) loss of cassava annually.
Doi adds that as a result of CBS disease prevalence now causing a scale-down in harvests, a new industrial enterprise along Soroti Road in Lira town, which buys maize and dried cassava from farmers to process into ethanol, is suffering low cassava supplies.
“I visited that factory this week and managers informed me they are facing serious cassava supply shortages. Yet they are a big opportunity for us farmers, but we cannot meet its demand for dry cassava quantities,” he said but did not quote the amounts the factory needs.
The farmer, who is establishing a 50-acre plantation in Inomo Sub-county, admitted he was targeting to supply the factory. He says the factory currently buys dry cassava at Shs900 per kilo which is over Shs300 above the ordinary open-market price.
“Today, farmers sell at Shs600-Shs650 in the open market for dry cassava per kilo. The factory offers better prices and they add value to our farm produce, which we want to see happen to all our agricultural produce. It creates employment and wealth,” notes the retired scientist.
It was not possible to establish contact with proprietors of the factory. But Doi says they are an agro-investment firm, who supply the ethanol to the local breweries and distilleries of spirits and other alcohols.
CBSD has negatively affected this industrial investment. Each year, it is estimated that at least 30 per cent of the cassava harvest in sub-Saharan Africa is lost to CMD, alone, an amount equal to $1.25b worth of production.
“Recently, CBSD has emerged an extremely serious and immediate constraint to cassava production in East Africa, and is poised to threaten production of the crop throughout the continent,” a VIRCA document adds.
However, CBSD is considered a more immediate threat than CMD to cassava production in East Africa because of both its recent rapid increase in geographical distribution and the dramatic effects on the yield and quality of cassava storage roots.
VIRCA also predicts that constraints that suppress yields will have an immediate and severe impact on the wellbeing of resource poor farmers.

Improved for resistance
Farmers in Lira complain of easy vulnerability to CBSD by the newer cassava varieties— Tropical Manihot Esculenta, the TME-14 and TME-204. These were supplied by Naads and are locally referred to as Gamente meaning a variety from Government.
“These are performing worse in terms of weakness to CBSD than Bao, our local variety from which we harvest at least some clean [un-diseased] roots,” said Geoffrey Ogwang, a farmer in Lira. NASE 14 is a more tolerant variety to CBSD that Ngetta Zardi are demonstrating and promoting.
But farmers in Lango and Nakasongola say they have limited access to NASE 14, which is the recommended CBSD-tolerant variety in the two regions.
Cassava farmers in Lira also associated whiteflies to the disease incidence and noted that during very dry periods white flies migrate to other wild host plants.
Cassava farmers in Nakasongola where CBSD is also widespread, acknowledged TME-14 as being their favorite variety. They suggested it should also be improved along with TME-204 for resistance. They called for more grassroots sensitisations on the new improved genetically modified variety that VIRCA is still developing.

Key statistics
According to a 2012 report by Uganda Biosciences Information Centre (UBIC) of Naro:
+10 million Ugandans consume cassava as main food
An estimated 75 per cent of Ugandan farmers grow cassava
Annual production is 6.7 million tonnes compared to potential of 30 million tons
Cassava brown streak disease (CBSD) is the main cause of yield losses
CBSD was present in 51 out of 54 districts surveyed in 2014
Estimated annual loss due to CBSD is $24.2m
Like other viruses, ‘vaccination’ of the cassava plants is the best option, to make the crop immune to CMD and CBSD.