The Fall Armyworm in Uganda: Is It A Scourge?

By: Charlotte B. Kemigyisha

In the latter part of 2016, this there were multiple complaints of outbreaks of “caterpillars” on maize plants in the districts of Kasese, generic Kayunga and Bukedea. A reconnaissance visit by sector officers revealed that close to 40% of the maize crops in the fields visited were attacked by an unknown pest.  It was also discovered that infestation of the pest at mid to late whorl stage of maize development could cause yield losses ranging from 15-73% at 55-100% levels of fall armyworm infestation. Needless to say, this coincided with drought and as a result farmers’ livelihoods were put at stake. In the past, Uganda had been infested by a similar pest commonly known as the African Armyworm but the damage this time by the new pest was immeasurable.

Subsequent DNA sequencing analysis carried out by the National Agricultural Research Organization (NARO) positively identified the new pest as a moth commonly known as the fall armyworm (Spodoptera frugiperda). The pest is a native to the tropical and subtropical regions of the Americas. There is a lot of speculation, however, on how the fall armyworm arrived in Africa. First observed in Nigeria in January 2016, the pest is now reported in several other countries including Togo, Ghana, Zambia, Zimbabwe, South Africa, Malawi, Mozambique, Namibia, Kenya Rwanda and Tanzania.

The fall armyworm is polyphagous in nature, feeding on more than 80 plant species in the categories of cereals, legumes and pasture grasses. In Uganda, the pest has so far been confirmed in at least twenty districts and damaging maize, sugarcane and pasture grasses among other crops.

According to UBOS (2016) report, maize is the fourth highest produced crop in Uganda contributing over US$100 million in forex earnings annually. It also contributes to the livelihoods of 3.8 million households in Uganda. Sugarcane, a primary ingredient for sugar products contributes over US$120 million in forex earnings annually and livestock contributes over US$60 million in forex earnings annually. The aggregated loss from these products would be close to US$300 million and that is the reason why we need to step up our investment in agricultural research to decisively address the fall armyworm.

In a Confined Field Trial (CFT) in Kasese by NARO, it was observed that the only maize variety that was resistant to the fall armyworm was Bt maize. Bt maize is a genetically modified maize variety using Bacillus thiurengensis. This variety however is not available on the market in the absence of a biotechnology and biosafety law.

The destructive stage of the pest is the caterpillar and it can be identified by its inverted “Y” mark on the front of the head and four large spots towards the end of the body. The colour of the larvae ranges from a light brown to dark army green at the later stages. It is worth noting that in its later stages, the gregarious caterpillars can destroy an acre of crop within 72 hours

To confirm the presence of the fall armyworm, look for creamy or greyish egg masses on the underside of leaves covered in a felt-like layer of greypink scales. The female moth lays upto 2000 eggs in batches of 150-200 eggs and the larvae are covered with plugs of yellowish brown frass. Small shot holes to large ragged and elongated holes in the leaves emerging from the whorl further confirm the presence of the pest.


Damage by the green caterpillar is characterized by perforation and defoliation of leaves, stems and cobs for maize crops. Any symptoms of such damage strongly suggest presence of the fall armyworm.

As a preventive measure, it is recommended that one plants early to avoid peak immigration of adults, removes and destroys all crop residues after harvest, deep plough the soil to bury the larvae and pupae and regularly weed the field and surroundings. After you have planted, you need to keep monitoring your fields for presence of the pest or symptoms from the 2-3 week stage.

Farmers are further advised to monitor damage on ten consecutive plants in ten randomly selected sites and to begin control measures immediately if 5-10% of the plants are infested with larvae.

In Ghana, small-scale farmers handpick the larvae and destroy the egg masses and larvae by putting a handful of sand mixed with lime or ash, sawdust or soil in the whorl of the attacked plants to kill the larvae.

As far as pesticide application is concerned two candidate pesticides; Lambda-cyhalothrin (Striker 247SC) and Thiamethoxam (Engeo K 247 SC) are being tested and the results are very encouraging. Farmers are advised to don protective clothing during the administering and disposal exercises of these pesticides. When applying pesticides, farmers are further encouraged to ensure that spraying of fields is regular for extermination of the pest. In the short term, the use of cultural methods and pesticides is encouraged and in the long term the use of natural enemies are being explored.

Zambia and Kenya have set aside $3,000,000 and $1,000,000 resepctively to mitigate the fall armyworm. Uganda has so far set aside Ush 1,200,000,000/= to mitigate the same pest. Our prayer is that a reasonable allocation is made to support agricultural research activities as this is how sustainable measures to deal with the fall armyworm will be attained.

Finally farmers shouldn’t panic because the ministry of agriculture and NARO together with other stakeholders are working round the clock to address the scourge of the fall armyworm holistically.

The Writter is the Principal Public Relations Officer, NARO

Twitter: @charlie_kemi

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