Devastation Overnight – Armyworms

These are dead worms after an application of cobalt advanced in Randlett, Okla. Worms are about a half to three-quarters of an inch. (Photo courtesy of T.J. Oatman)

By Jessica Crabtree 

Fall armyworms, Spodoptera frugiperda, are not an uncommon nuisance across north and central Texas crops. The tiny torturers have a wide variety of hosts or food sources they migrate to. That includes pasture grasses, corn, grain sorghum, rice, wheat, even turf grass and landscaping plants. Although they are small, their size holds no reflection of their life cycles and population produced per generation.

Wet weather is a good indicator to producers that fall armyworms are to follow. Across North Texas and southern Oklahoma, mid-October brought producers a bitter pill when winter wheat crops were compromised from fall armyworm infestations. This year in North Texas, ample moisture and timing were really to fault. As Helena Sale’s representative T.J. Oatman said, “A lot of farm ground didn’t get plowed this year. The extra rain provided ample forage and a safe haven for the moths in Bermuda, grass and even weeds. It kind of set up the perfect storm.” Oatman explained moths are attracted to the best, most lush green tender vegetation.

As wheat emerged, the moths followed. 2016 saw pockets of armyworm issues. While advising growers and custom applicators on both sides of the Red, Oatman said this year the affect of armyworms is more wide-spread. The fall armyworms are great travelers, beginning their path of destruction in South Texas and Mexico, moving north, generation by generation. They even travel as far as Canada. Producers can begin surveying their fields at the end of August for signs. Signs may include spots where the surface of a leaf has been chewed on, but not all the way through. Experts in Texas AgriLife

Extension refer to this as window paining. At this stage they are too small to chew any further. An infestation begins with an adult moth flying in and laying eggs in clusters on various foliage. Those eggs hatch and emerge into six larval stages. The most damage done to plants is during the larval stage as they consume foliage.

According to a recent video produced by the Noble Research Institute “Fall Armyworms: Identification, Damage Indications and Control,” experts explained the first four larval stages make up 20 percent of what the larval will eat during their entire life cycle. This is all before they are even a half inch in size. During their last two larval stages, the fifth and sixth, the armyworm will grow up to one and a half inch long.

To read more pick up a copy of the December 2017 NTFR issue. To subscribe call 940-872-5922.