Red alert as wheat blast hits Africa

We’ll Ensure NAQS Vigilant
There is a looming threat to Wheat sufficiency in Africa, as a dreaded plant disease-Wheat Blast has hit the continent for the first time, since its initial discovery in 1985.

Though currently ravaging Zambia, the outbreak poses danger to rain-fed wheat production across countries on the continent, with similar environmental conditions as Zambia.

The outbreak was reported in a new article published by scientists from the Zambian Agricultural Research Institute (ZARI), the International Maize and Wheat Improvement Center (CIMMYT) and the US Department of Agriculture – Foreign Disease Weed Science Research Unit (USDA-ARS) in the scientific journal PLoS One.

Wheat blast is a fast-acting and devastating fungal disease that threatens food safety and security in tropical areas in South America and South Asia. Directly striking the wheat ear, wheat blast can shrivel and deform the grain in less than a week from the first symptoms, leaving farmers no time to act.

The disease, caused by the fungus Magnaporthe oryzae pathotype triticum (MoT), can spread through infected seeds and survives on crop residues, as well as by spores that can travel long distances in the air.

Officially identified first in Brazil in 1985, the disease is widespread in South American wheat fields, affecting as much as three million hectares in the early 1990s. It continues to seriously threaten the potential for wheat cropping in the region.

In 2016, wheat blast spread to Bangladesh, which suffered a severe outbreak. It has impacted around 15,000 hectares of land in eight districts, reducing yield on average by as much as 51 per cent in the affected fields.

According to experts, the development signals severe danger to wheat farmers in Africa, considering the importance of wheat as a staple food, coupled with efforts of several countries in the continent towards reducing dependence on wheat imports.

It is gathered that the symptoms of the disease first appeared in Zambia during the 2018 rainy season in experimental plots and small-scale farms in the Mpika district, Muchinga province.

The wheat breeder at ZARI and lead scientist on the study, Batiseba Tembo, said the first occurrence of the disease was very distressing. “This happened at the spike stage, and caused significant losses. Nothing of this nature has happened before in Zambia.”

Researchers were initially confused when symptoms of the disease in the Mpika fields were first reported. Zambia has unique agro-climatic conditions, particularly in the rain-fed wheat production system, and diseases such as spot blotch and Fusarium head blight are common.

“The crop had silvery white spikes and a green canopy, resulting in shriveled grains or no grains at all…Within the span of seven days, a whole field can be attacked,” said Tembo. Samples were collected and analyzed in the ZARI laboratory, and suspicions grew among researchers that this may be a new disease entirely.”

President of the Wheat Growers Association of Nigeria, Saleh Mohammed, who told The Guardian that the National Agricultural Quarantine Service (NAQS) would be put on red alert to avert the disease coming into the country, said the body would also find time to study and analyze the wheat disease.

“We are going to train our people properly to apply anti-virus chemicals on their seeds before planting, to prevent the disease in the country,” he said.

To curtail the spread of the disease, it was learnt that CIMMYT and the CGIAR Research Program on Wheat (WHEAT) are taking action on several fronts to combat the wheat blast.

Reports have it that trainings, such as an international course led by the Bangladesh Wheat and Maize Research Institute (BWMRI) in collaboration with CIMMYT, WHEAT and others, invited international participants to gain new technical skills in blast diagnostics and treatment and understand different strategies, are being developed to mitigate the wheat blast threat.

WHEAT scientists and partners are also working quickly to study genetic factors that increase resistance to the disease and develop early warning systems, among other research interventions. 

Senior Scientist and Head of Wheat Pathology (CIMMYT), Pawan Kumar Singh, said: “A set of research outcomes, including the development of resistant varieties, identification of effective fungicides, agronomic measures, and new findings in the epidemiology of disease development will be helpful in mitigating wheat blast in Zambia.”

Tembo said it is imperative that the regional and global scientific communities join hands to determine effective measures to halt further spread of this worrisome disease in Zambia and beyond.