By John Daniels, agronomist, Central Region
|Fall armyworm infestations have the capability to take out turf overnight.|
High populations of fall armyworms recently have been seen damaging bermudagrass in areas of Texas and Oklahoma. Sites that received ample rainfall or irrigation during September have been especially hard-hit. Succulent, newly emerged bermudagrass leaves are a preferred environment for adult moths looking to lay their eggs and offer a tasty treat for the emerging larvae.
In such environments, the potential for turf loss is significant. A single female moth is capable of depositing more than 1,000 eggs that can hatch within a few days. Fall armyworm larvae have five stages, or instars, that occur over a three- to four-week period. It is during the latter two stages when the majority of feeding occurs.
Early detection is crucial to avoiding widespread damage as fall armyworms can quickly strip all of the green foliage from a turf area. On golf courses, feeding typically occurs within the rough and on newly sodded areas. Symptoms may resemble drought stress from afar but typically occur more rapidly than drought stress and in sites with sufficient soil moisture. In most instances, fall armyworm caterpillars will be visible under close inspection of the turf. A soapy water flush with lemon-scented dish soap can help to expose larvae that may be hiding in thatch layers. Fall armyworm larvae can be identified by the characteristic, inverted white “Y” on their head.
Continue to scout daily for fall armyworm activity to limit damage and improve the efficacy of treatments. It is much easier to control younger caterpillars. Insecticide control measures are recommended in areas where high populations are detected – i.e., three to four armyworms per square foot – or where excessive damage is observed. Effective insecticides include bifenthrin, carbaryl, esfenvalerate, permethrin and others.