• August 4th, 2020

‘Hungry armyworms’ - what you need to know



Emilie Abraham 

Agronomic pests are among the most detrimental hindrances to crop farmers and can result in significant losses. Although pest damage differs in severity, the bottom line is that they reduce crop yield, exaggerate production costs and ultimately make the crop enterprise unrewarding. Farmers today equate farming to gambling, as with every cropping season they are uncertain of what the outcome will be. 
However, it should be noted that with proper contingency planning, farmers can easily hit the Jackpot. It should be noted that armyworms are among the hungriest pests that destruct crop fields unapologetically and can drastically reduce yield per unit area, particularly if mitigation measures are not in place in a timely manner.

It should be noted that Fall armyworm outbreaks frequently occur during periods of drought or after prolonged dry spells (drought) as most of their natural enemies (e.g. birds, ground beetles, and rodents amongst others), which could eliminate or reduce their numbers are suppressed during drought periods, leaving armyworms to populate. 

Thus, grass and plants from the recent rain that have broken the prolonged dry period of last year could perhaps trigger the current outbreak of armyworms in Namibia. Thus, this article seeks to articulate the impact of hungry armyworms and remedial actions that farmers should consider to win the battle with hungry armyworms.

Knowing Fall armyworm (FAW) moths are responsible for laying eggs that hatch into larva/worms; thus, most people may observe the presence of numerous moth populations during the December and January months, more particularly at night. 

Female armyworm moths are ash-gray in color, and several research efforts revealed that one female armyworm can lay egg masses ranging from about 1,500 to 2,000 at night, and usually place their eggs on plant foliage. Hatching takes place within two – four days allowing them to populate in a very short period. Researchers have revealed that heavy rains can disrupt the life cycle of fall armyworms by washing eggs off leaves and onto the ground. If the production cycle goes undisrupted, eggs can hatch into larva, which can be described as light green to cream in color with a dark head capsule. 

As the larva continues to feed and molt, it becomes darker with light-colored lines down the sides of its body. Thus, the adult fall armyworms can be distinguished from other worm pest species by the inverted Y on the head capsule and four dots on the abdomen. 

Hungry fall armyworms feed at any time of the day depending on the height of the crop and canopy. However, they are most active in the early morning or late evening hours. Most farmers believe that armyworms cause damage overnight.

 However, armyworm larvae can feed for a week or more before the damage becomes visible. Thus, farmers are advised to be vigilant and scout their fields frequently as small armyworms (early instars) feed less and as they grow, (5th and 6th instars) their feed intake increases significantly to such an extent that the feeding patterns can be easily noticed. 

Thus, farmers shouldn’t wait for extreme damage to occur, close crop inspection is required to detect the pest on time. 2.) Scout diligently Farmers are advised to prioritize scouting to detect armyworms and the presence of other pests in the field in a timely fashion. 

This is to ensure that appropriate management decisions are embarked on to inform integrated pest management (IPM). Moreover, it should be noted that the effective control of armyworms can be achieved when pesticide application is done promptly. 

Furthermore, it is imperative to scout in the morning and afternoon hours while pests are active and can be easily detected. Scouting can be performed in different methods, this can include V, M or Z shaped amongst others and irrespective of the scouting method employed, and farmers are advised to investigate the crop leaves in their entirety. 


Staff Reporter
2020-02-18 08:38:27 | 5 months ago

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