(Backyard Gardener - Photo Illustration - MetroCreativeConnection)

Hello Mid-Ohio Valley farmers and gardeners! We continue to experience plenty of rain and mild temperatures as summer comes to a close in a few weeks (Sept. 22). All of this moisture and cool temperatures makes this fall a great time to overseed the lawn and apply a good fertilizer to build roots for next year.

Do not forget to take a soil test this fall for gardens, lawns, crop fields and flower beds. Once you find out what nutrients your soil is lacking, you can apply lime, fertilizer and compost this autumn so they can incorporate into the soil over the winter.

This week I want to talk about the fall armyworm (spodoptera frugiperda, family noctuidae). I have received a few calls at the Extension Office about this pest causing injury to turfgrass. It can also feed on hay, pasture fields and row crops.

Fall armyworms have been reported causing significant damage on forage grasses, turfgrasses and pipeline vegetation cover around the Mountain State in the past few weeks. Fall armyworms are not picky and will feed on over 80 plants species.

They can cause significant damage to field crops, including alfalfa, barley, Bermuda grass, buckwheat, clover, corn, oats, millet, sorghum, sugar beets, Sudan grass and soybeans.

However, their favorite foods are grasses, including rye and wheat. Occasionally, fall armyworm injures apple and peach trees, grapevines and strawberry plants.

Armyworms earned their name because of their habit of moving in massive numbers, similar to an army marching to another battle. Once they’ve depleted their food supply, they search for more plant material to engulf. Caterpillars will move from field crops into nearby turfgrass if they run out of a food source.

Once they move into turfgrass, the caterpillars will continue feeding until there is no more food or they complete their development, whichever comes first. If the food source from plants is exhausted, armyworms will become cannibalistic and the larger caterpillars will eat the smaller ones.

Fall armyworms are a semi-tropical species. They overwinter in southern Texas and southern Florida and begin working their way north each season. The moth is a strong flier, and this pest can be found in most states east of the Rocky Mountains.

The adult fall armyworm is a moth with shaded gray and brown forewings with triangular white spots at the tip and near the center of the wing. The hind wing is iridescent silver-white with a narrow dark border.

Adults are nocturnal, and are most active during warm, humid evenings. Females normally deposit most of their eggs during the first four to five days of life. They only live from 10 to 21 days, so they do not have time to waste.

Fall armyworm larvae are approximately 1-1¢ inches long, depending on instar, and can vary in color from a green to mottled brown, to almost black. They have wide black stripe running down each lateral (side) of the body.

Sometimes, you will be able to distinguish four black dots on the dorsal (back) side of each segment of the abdomen and a light-colored, upside-down “Y” marking on the head capsule. Similar to some other immatures of moth species, they have four pairs of prolegs attached to the abdomen.

Caterpillars tend to conceal themselves during the brightest time of the day. The larval (caterpillar) stage tends to be about 14 days during the summer and 30 days during cool weather.

Late in June, fall armyworms arrive in West Virginia from the south. Shortly after, eggs are laid in masses on the undersides of plant leaves, tree trunks, undersides of tree limbs and other structures near suitable host plants, such as fences, bleachers and light posts. Outbreaks, or large numbers, of armyworms may occur every few years.

Fall armyworm larvae feed as a group and can devour an entire lawn or hay field in a matter of a few days. Damage is caused by caterpillars feeding on plant tissue.

Fall armyworm damage often resembles drought damage. The grass may seem to thin out and develop brown spots, which look burned or browned out. This appearance is the result of grass plants rapidly dehydrating after fall armyworm larvae damage.

Cold temperatures in fall will reduce the armyworm’s onslaught of destruction. Feeding is reduced by and the insects will die with the first frost.

There are natural enemies which attack fall armyworms. However, few act effectively enough to prevent crop injury. Predators of the fall armyworm are insects which feed on caterpillars including various ground beetles, the spined soldier bug, the insidious flower bug, the striped earwig and others. Birds, skunks and rodents will consume the larvae and pupae and help to reduce armyworm populations.

Farmers, turfgrass managers and homeowners should scout their fields every three to four days to monitor for caterpillars in July, August and September. Treatment is recommended when more than three worms of 1/4-inch in length or greater are found in a 1-square-foot area.

If a hayfield is close to harvest, producers should go ahead and harvest early. If you round bale and make baleage, wrapping bales will help contain the insects. If bales are not wrapped in plastic, do not transport over other fields to avoid spreading the insect.

Cattle can also be used to intensively graze the forage before the caterpillars consume it all. If more growth is required before harvesting hay, or you are stockpiling forage, treatment is recommended as soon as conditions allow. See label directions for weather and harvest/grazing intervals.

There are multiple chemical control options for fall armyworms. For farmers, products containing diflubenzuron (Dimilinç) or methoxyfenozide (Intrepridç) are insect growth regulators that disrupt the pest’s life cycle and work best on small caterpillars. Residual control is approximately 10 and seven days, respectively, but both will cease to provide control following a rain.

Pyrethroids (Mustangç, Maxxç, Karateç, Warrior IIç) will provide more immediate knockdown but have a shorter residual and stop providing control following a rain. Products containing chlorantraniliprole (Prevathonç, Beseigeç) are taken up by the plant (systemic), so they will still be effective after a rain.

Products for home lawns will usually be labeled for caterpillar pests rather than specifically for fall armyworms. Most products are granular formulations of pyrethroids. If using a granular formation or RTU (Ready-To-Use) spray formulation, there is no dilution or equipment required.

Control will depend on good coverage. For the lawn, mowing may mechanically kill a few caterpillars but will not provide adequate control. The lawn should be mowed before applying an insecticide to reduce the distance the chemical must penetrate.

For a more organic approach, products containing spinosad or Bacillus thuringiensis (Bt) will control smaller caterpillars without harming beneficial insects. Products that contain spinosad include Entrustç, Captain Jack’s Deadbug Brewç, Conserveç, Monterey Garden Insect Sprayç and many others. Products with Bt include Thuricideç and Dipelç.

Products containing active ingredients such as cyfluthrin, bifenthrin, carbaryl, malathion and lambda-cyhalothrin will also kill fall armyworms. However, these are broad-spectrum insecticides and can be harmful to beneficial organisms. Read and follow label directions on all pesticides.

Questions? Contact me at the Wood County WVU Extension Office 304-424-1960 or e-mail me at jj.barrett@mail.wvu.edu. Good luck and happy gardening!