Fall Army worm

THE FALL ARMY WORM IS A DEVASTATING PEST THAT DEMANDS ALL
FARMERS’S ATTENTION!! VIGILANT EARLY DETECTION IS CRUCIAL!!

Scouting, detection and pest identification

Early detection is crucial; monitor by scouting crops every 2 days starting from the current wind direction, checking borders and centres of crop fields. Note all egg parcels, new hatchlings or young larvae penetrating the whorls. See attached pictures for easy identification. Egg parcels are covered by a woolly cover. The larvae are quite easy to identify: looking at the larva from its head gives the appearance of a dragon fly face with the markings on the head. Four dark spots in a square are also clearly visible on the 8th segment. Their colour varies from green to dark green, pinkish, brown or dark brown with paler green longitudinal stripes. DO NOT CONFUSE THIS SPECIES WITH THE AFRICAN ARMY WORM OR THE FALSE ARMY WORM. CHECK THE HEAD AND 8TH SEGMENT FOR THE DIAGNOSTIC CHARACTERISTICS! To see pictures click here

Control
Spray insecticides as soon as the pest is noticed or if 5 – 10% of plants show infestation, e.g. 5 or 10 plants per 100 plants inspected. Use those active ingredients that have already been approved for the fall army worm. (For product in RSA see table below).
DO NOT APPLY PYRETHROIDS ON THEIR OWN AS THIS SPECIES APPEARS
TO BE TOTALLY RESISTANT TO PYRETHROIDS!!!
=>Insecticides must be applied during the early development stages of larvae. Adult larvae may prove to be very difficult, if not impossible to control.
=>The best control is obtained when larvae feed on exposed leaf surfaces where insecticides can reach them outside cobs, ears and tassels.
=>As soon as larvae penetrate too deep into the whorl or feed inside the cob nothing will effectively control them. Small larvae are easier to control than that fully-grown larvae that can reach up to 40 mm in length.
=>Farmers are urged to refrain from using any concoctions or unregistered mixtures and to adhere to the label specifications and dosage rates of the registered products.
=> Select the appropriate insecticide, apply according to label recommendations and dosage rates.
=> Control varies from very poor to adequate when carbamates and organophosphates are used; it is advisable to test any carbamates and organophosphates on a small patch for efficacy before using
it on a large scale.
=>Certain strains of Bacillus thuringiensis may not be effective against fall army worm; as with the carbamates and organophosphates it is advisable to first test the product on a small patch before deploying it on a large scale.
=> Calibrate sprayer and maintain nozzles and equipment, make sure it is in good working condition, delivering the expected droplet size and spray volume.
=> Aim nozzles at plant rows and not between rows to ensure that the target is reached with the maximum spray volume.
=> Use optimal spray volumes and best management technique; on average between 200 – 400 l/ha for maize crops should be adequate to deposit active ingredients on the target. Always refer to labels for instructions.
=> Adjust water pH and add adjuvants if necessary in accordance with label recommendations.

Resistance management
=> Rotate pesticides groups with different modes of action (MoA) as indicated on the front panel of each pesticide label; simply rotating between active ingredients of the same MoA is not conducive to resistance management.
=> Avoid treating consecutive generations of the fall army worm with pesticides with the same MoA.

Source: Crop Life of South Africa

The list of Government recommended pesticides for Fall Armyworm in Malawi