Fall armyworm presence has been detected by 31 African countries as of August 2017. And it is likely to spread into the Middle East and eventually to Europe, according to Professor Kenneth Wilson at the UK’s Lancaster University, who has extensive experience working on the African armyworm.
The fall armyworm has now arrived in Africa from the Americas and is here to stay. It will not be eradicated. This is the conclusion of several fall armyworm experts at a meeting supported by the United Nations Food and Agriculture Organization (FAO) and held in Accra, Ghana, in late July 2017.
Following this conclusion, tens of millions of maize farmers across Africa have to learn how to save their crops from fall armyworm. In sub-Saharan Africa, over 95 per cent of maize farmers are smallholder family farmers. They often grow a diversity of crops, with limited access to inputs and services, and frequently receive low prices for the maize they sell to markets.
A conservative estimate indicates the loss of Africa’s maize due to the fall armyworm could cost the continent USD 3 billion in the coming year, as Dr Roger Day, sanitary and phytosanitary coordinator at the Center for Agricultural and Biosciences International (CABI), stated in May 2017.
Nevertheless, feeding on leaves, fall armyworm mostly causes indirect damage. Occasionally it attacks the cobs or burrows into the stem. While very dramatic looking, leaf damage can be compensated for by a well-fed and watered maize plant, according to experts.
Leaf feeding by fall armyworm can cause some yield reduction, but the damage may look far worse than the impact on yield. Even with high levels of fall armyworm infestation at certain periods, maize plants are capable of compensating for the damage and not significantly reducing yield.
The fall armyworm mainly affects maize crops, but also thrives on rice and sorghum as well as cotton and some vegetables. It has the potential to feed on more than 80 plant species. To reduce fall armyworm oviposition on maize, experts recommend increasing plant diversity.
Intercropping with cassava, which is not a fall armyworm host plant, is suggested in particular. Some other plants “repel” adult fall armyworm and could be planted in rows. Furthermore, plant diversity can increase natural enemy populations.
Allowing the fall armyworm’s natural enemies – predators, parasitoids or pathogens – to build up in affected areas can provide a cost-effective and natural or biological control against the spread of this crop pest, without the damage to human health or the environment that pesticides can cause.
Experts say that, in combating fall armyworm infestations in sub-Saharan Africa, farmers should use chemical pesticides against which the harmful insects can build resistance as little as possible, also because the technique is neither economically nor environmentally sustainable and could present health risks.
Map of African areas affected by fall armyworms