Uganda’s scientists looking for possible solutions for cowpea disease outbreak

Two years ago, scientists in Uganda developed and released high yielding varieties of cowpea resistant to Aphid born mosaic virus to farmers aimed at addressing of food scarcity especially in semi-arid areas.

The cowpea varieties; Secow 3B, Secow 4W and Secow 5T were given to the farmers in May 2011, after four years of vigorous research.

But as researchers at the National Semi Arid Resources Research Institute, Serere (NaSARRI) starts developing foundation seed for the farmers and the seed companies; they have been hit with the re-emergence of cowpea scab and leaf blight diseases, threatening the crop in the country.

Dr. Peter Obuo, the lead researcher at the institute for the dry land legumes said Cowpea scab and leaf blight diseases were not a threat at the time the crop’s high yielding were released to farmers for growing.

“…At the moment, the two diseases have become a serious threat to the crop possibly because of climate change and we are looking carrying out research,” Dr. Obuo said.

“We are looking at three approaches, either developing disease resistant materials for the crop, using a chemical control, using an agronomic practices or coming up with an integrated approach.”

In November last year, scientists in the country’s research institutions warned of a possible increase in the spread of viral diseases in crops as raising temperatures resulting from climate change create and enabling environment for them to thrive.

Whereas Cowpea scab disease affects the flowering axis causing the flower and, or, pod abortion or completely preventing flower formation, Bacterial blight causes chlorotic patches (orange with a yellow halo) and necrotic patches on the leaves.

Bacterial blight is transmitted from infected seedlings to adjacent plants by rain drops and the pathogens can also cause cracking and cankers on the stem and peduncles.

Cowpea is one of the most important grain legumes in arid and semi-arid regions of sub-Saharan Africa used as a nutritional source of protein for poor rural farmers.

It is also a source of nutrition in drier regions, especially in eastern and northern Uganda, where diets heavily rely on starchy foods such as sorghum, millet, maize and cassava.

Some farmers consume cowpea as both grain and a vegetable and as a source of income for subsistence farmers.
Compared to other grain legumes and vegetable crops, cowpea possesses multiple advantages for farmers, including high yields on poor sandy soils unsuitable for other crops, high rate of nitrogen fixation, lower fertilisers and tolerance to drought and high temperatures.

Research on the development of high yielding cowpeas begun in 1986 with the crossing of 20 lines from Tanzania, 110 lines  from the International Institute of Tropical Agriculture (IITA) and 57 local germplam.

Mr. Robert Ameyo, a plant pathologist at NaSSARI said it was until 2005 that the institute was able to fully develop and release two varieties of cowpea; Secow 1T and Secow 2W.

“Though the crop varieties were high yielding, they were not resistant to Aphid borne diseases,” Mr. Ameyo said.

The outbreak of Aphid borne disease led to a further breeding of three more cowpea varieties with germplasm from IITA,   local cowpea variety and the already developed high yielding Secow 1T and Secow 2W. END