Fall Armyworm

The correct identification of fall armyworm (Spodoptera frugiperda) is critical to implementing control options to stop the caterpillar pest, which can significantly damage plants and reduce crop yields. It is important to consider whether the cost of taking action does not exceed the value of lost crop yield if no action is taken.

Detection and identification

Fall armyworm are known for their ability to devastate crops fast and reproduce several generations in a single season. Early detection is imperative in choosing an effective course of action to target egg and larval stages of the pest.

Control measures

The timely implementation of control measures can successfully eradicate fall armyworm, but it can be expensive. Consider whether the cost of using the amount of pesticides needed to stop the pest will be worth it financially. As there may be multiple fall armyworm infestations within a season, several treatments may be required. That cost could exceed the value of lost crop yield if no action is taken.

In making your decision, refer to the recommended threshold values in our fall armyworm resources via the link below. Consult with an experienced local agronomist familiar with fall armyworm outbreaks before choosing biological or chemical control options. Follow label and permit directions for individual insecticides and rotate insecticides that belong to different modes of action groups.

Agronomic management

In northern growing areas of New South Wales (north of Dubbo), there is greater likelihood of fall armyworm incursion due to warmer, winter months. Compared with spring planting in the region, plantings in January to February, are more likely to have fall armyworm incursions and require a higher number of control treatments.

Consider forage type because maize is more susceptible than sorghum to infestations and damage by fall armyworm. It is recommended to avoid sequential plantings of crops such as maize and sorghum, to help reduce local populations of fall armyworm.

Damage

Maize, sorghum, and other crops can tolerate various levels of damage from fall armyworm to leaves without yield impacts. If sorghum is impacted in the early stages of growth, it is more likely to successfully grow through that damage. There is also a good chance that the seedhead of the crop is unaffected by the pest, due to its open nature.

However, Maize can be potentially destroyed if attacked by fall armyworm in the early growth stages. High incursion levels are particularly damaging, resulting in lower yields and quality. If maize is impacted later in the growth stage, there is also a risk of damage to the cob and the development of mycotoxins in the subsequent silage.

Resources

For more information and support with managing fall armyworm and estimating the costs of control measures, access our resources.