Zimbabwe: Centre develops new hybrid maize resistant to armyworm

By Sifelani Tsiko, Agric & Innovations Editor

The International Maize and Wheat Improvement Centre (CIMMYT) has developed new maize hybrid varieties showing promising resistance to the destructive fall armyworm pest which has been causing huge crop losses ever since the pest was first reported in Africa in 2016.

Fall armyworm (Spodoptera frugiperda) has emerged as a serious threat to maize production in Africa and continues its devastating advance.

CIMMYT worked intensively over the past three years to identify and validate sources of native genetic resistance to fall armyworm on the continent by screening over 3500 hybrids in 2018 and 2019 in Kenya. Tests were also done in Tanzania.

It did so by leveraging tropical insect-resistant maize germplasm developed in Mexico in addition to stress — resilient maize germplasm developed in sub-Saharan Africa.

The trials for fall armyworm tolerance were evaluated in 2020 for a set of eight test hybrids (four early-maturing and four intermediate-maturing) against four widely used commercial hybrids (two early- and two intermediate-maturing) as checks.

During the trials, each plant was infested with seven fall armyworm neonates 14 days after planting while foliar damage was assessed 7, 14 and 21 days after infestation.

Ear damage and percent ear damage were also recorded, in addition to grain yield and other agronomic parameters.

Selected varieties were evaluated for their performance under managed drought stress, managed low nitrogen stress and under artificial inoculation for Turcicum leaf blight (TLB) and Gray leaf spot (GLS) diseases.

The three-way cross CIMMYT test hybrids and their parents were also characterised on-station for their seed production capacity, including maximum flowering time difference between parents, and single-cross female parent seed yield.

“Native genetic resistance to fall armyworm in maize is partial, though quite significant in terms of yield protection under severe fall armyworm infestation, as compared to the susceptible commercial checks,” CIMMYT researchers said in a report.

“Sustainable control of fall armyworm is best achieved when farmers use host plant resistance in combination with other components of integrated pest management, including good agronomic management, biological control and environmentally safer pesticides.”

CIMMYT now plans to nominate hybrids for varietal release in target countries in sub-Saharan Africa, especially in eastern and southern Africa.

“After national performance trials (NPTs) and varietal release and registration, the hybrids will be sublicensed to seed company partners on a non-exclusive, royalty-free basis for accelerated seed scaling and deployment for the benefit of farming communities,” CIMMYT said.

The development of maize varieties resistant to the voracious fall armyworm could well be a game changer in efforts to ensure Africa’s food security.

The seeds can offer significant protection against insect pests — without the use of pesticides.

FAO estimates that the pest has caused economic damage that ranges between US$1 billion to US$3 billion on the entire African continent.

It also estimates that between 20 and 40 percent of global crop yields are reduced each year due to the damage wrought by plant pests and diseases. The first report of the fall armyworm in Zimbabwe was in 2016 when the pest was detected in the Bubi district of Matabeleland North province.

The fall armyworm pest was first reported in Africa in 2016. Native to the Americas, the fall armyworm can feed on 80 different crop species, including maize — Africa’s major staple food consumed by more than 300 million people on the continent.

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