ARMY WORM: THE BANE OF MAIZE FARMERS

Sometime in 2016, I wanted to undertake a crop production project. After a series of deliberations, I decided to embark on maize production. I mean, maize is needed by all and sundry.  While trying to seek technical guidance on how to proceed, I contact an agronomist and senior lecturer of my Alma Mata seeking his opinion. He told me ‘’ I have not embarked on maize experimentation this year because of the new guy in town, Fall Armyworm”, he said.

This is not the first, I have heard producers and researchers provide reasons why maize production has been inhibited. He strongly advised me to consider other alternatives because as at that time, the fall armyworm can destroy up to 80% of a cornfield. John Tezugar, a renowned maize farmer in Garam, Niger State, said he lost over 80 per cent of his farm to the worm in 2018.

Fall Armyworm (FAW), or Spodoptera frugiperda, is an insect pest that is native to tropical and subtropical regions of the Americas. In its larval stage, it can cause significant damage to crops, if not well managed. It prefers maize but can feed on more than 80 additional species of plants, including rice, sorghum, millet, sugarcane, vegetable crops and cotton. The adult is a moth and the damaging stage is the caterpillar. It is a nocturnal pest. FAW is a highly migratory and transboundary pest.

Armyworm Life History

• Pupae over the rainy season in the soil is present in southern climates
• Adults migrate north in April and May and lay eggs in clusters on lower leaves of grasses or small grains
• Eggs hatch in 1-2 weeks depending on temperature
• Larvae feed mostly at night or on overcast days; during sunny days they may remain hidden in ground litter or behind leaf sheaths
• Because adults are migratory and the flight is strongly dependent upon weather fronts, injury is sporadic in an area from 1 year to the next
• There are 2-3 generations per year, but rarely in the same fields

Armyworm Identification

• The adult moth is pale gray to pale brown, with a white speck in the centre of each front wing

Larva

• 1½ inches long when fully grown with 2 “orange” stripes alongside and 2 dark stripes on the back
• 4 pair of abdominal legs often have a lateral dark bar (see arrow in the photo below)
• Head with 2 vertical bars on the face

In Africa, FAW was first detected in Nigeria in January 2016 and has quickly spread across virtually all of sub-Saharan Africa. Because of trade and the moth’s strong flying ability, it has the potential to spread further. In 2016, the fall armyworm invaded maize crops in Zambia.  By January 3, 2017, about 90,000 hectares were affected according to reports released by the Zambian Government’s Disaster Management and Mitigation Unit. The Zambia National Farmers Union indicated that some farms were completely wiped out. The Zambian president directed the air force to help airlift pesticides to fight the outbreak.

INJURY TO CORN (SEE APPENDICES)

• Armyworm larvae feed only on the leaf margins; they do not tunnel into the stalk or feed in the ear
• Severe defoliation (below) removes the softer leaf tissue, leaving only the stalk and tougher leaf midribs
• Plants will recover from moderate levels of injury unless the growing point has been damaged
• Field-wide defoliation may occur if the population is large, which is most likely in fields with weedy grasses.

Pest Status

• Army worm is an uncommon pest of maize.
• Economic damage is rare in conventionally-tilled fields
• Injury most commonly occurs in reduced-tillage fields with grassy weeds or a grass cover crop
• Moths lay eggs on grasses before corn is planted, then when a herbicide is used to kill the grass, the larvae move to the young corn plants
• Larvae also will migrate from adjacent cereal small grains when that crop approaches maturity

CONTROL:

This pest can be controlled by Integrated pest management. The use of non-ecofriendly chemicals on FAW poses a threat to the safety of crops they are applied and also these chemicals leave residues on the environment which further degrades the environment. A combination of the mechanical, biological, botanical, chemical, cultural method of pest control can help prevent and control the menace of the Fall Armyworm.

Yours truly,

Happy Farmer.

Written by Joseph Okpaire