Fall armyworms are back


FALL armyworms (FAW) are back in Zambia and poised to once again cause damage to maize fields.

In the 63rd edition of the online News Diggers newspaper on Tuesday November 21, a maize farmer was captured showing the fall armyworm in the newly germinated maize crop.
Of late, armyworms have been reported to invade maize fields in Lundazi, district.
The fall armyworm (Spodoptera frugiperda) that was positively identified in Zambia last farming season still poses a threat to the staple food crop, maize, and will be a familiar unwelcome guest for a long time.
This destructive pest that has developed an avaricious appetite for the maize crop was identified in the entire SADC region and East Africa in recent years.
Unlike its cousin, the armyworm, the larval stage of FAW is more devastating as it feeds both during the day and at night.
The adult FAW moth can fly distances of up to 100km at night, hence its high potential of continuing to spread.
A FAW larva has a broad, pale band along the top of the body contrasted by a dark stripe at the sides. At the eighth abdominal segment near the tail end, it has four dark spots.
The head has a dark net-like pattern while its underside has a white ‘Y’ marking.
The FAWs that attacked maize fields in Zambia from December 2016 onwards were reported to have affected more than 115,000 hectares of maize fields and cost Government at least K30 million worth of pesticides.
But this was not until they inflicted considerable damage to crops.
Some farmers’ maize fields were completely destroyed.
According to the FAO regional office in southern Africa, FAW is still a danger to the region and may cause a food crisis in some countries.
The Centre for Agriculture and Biosciences International (CABI) predicts that Africa may lose up to US$3 billion worth of maize in the current farming season if the FAW is not managed well.
Pesticide control of the FAW is achieved when the worm is still young between day three and six of their four-week life cycle.
As the caterpillars grow older, they become increasingly difficult to kill with pesticides because they hide inside the maize foliage, thereby avoiding direct contact with the pesticide while they cause more damage to the plant. The pest is also known to develop resistance against pesticides if not varied.
FAO therefore advises that pesticides should be used to a bare minimum to prevent a build-up of resistance and damage to the environment.
While there is no silver bullet to the FAW threat, the first line of defence is integrated pest management (IPM) strategies.
Farmers must therefore embrace all good crop management practices that can sustainably control the pest.
Continuous growing of maize on the same piece of land promotes FAW infestation.
Farmers must therefore practise crop rotation to avoid a build-up of the FAW.
Crop residue in infected fields must be burnt to reduce food and hiding places for the caterpillars.
Farmers must be vigilant and scout for early signs of the FAW and must immediately notify the ministry of agriculture once they locate suspicious pests.
Deep ploughing in crop fields that have a history of FAW infestation is beneficial as it brings the young pupae to the surface.
To avoid periods of heavy infestations later in the farming season, farmers must sow the seeds as early as possible.
In the long run, Government must ensure that research institutions breed resistant maize varieties that cannot be attacked by the FAW.
Research institutions should experiment on the use of locally available natural FAW pest enemies like wasps.
Government should quickly adopt the use of Remote Sensing (RS) technology for pest surveillance to ensure that pests like the FAW are quickly detected in farmers’ fields.
FAW was also detected in the irrigated winter maize from July to August 2017 in the neighbouring Zimbabwe.
This is despite the fact that caterpillars detest the cold weather.
This signifies that the threat is real and the sooner the nation acts to thwart the imminent threat FAW poses to food security, the better.
The author is a sustainable agriculture and rural development professional.

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