It’s is not a common annual problem but I have been getting some questions on fall army worm in lawns. They feed primarily on grasses, although they will sometimes feed on nongrass species.

Young worms are ½- to ¾-inch long. Mature ones are 1 1/2 inches long. Body color may vary from green to almost black but light stripes will be visible along the length of the body. Look for a whitish inverted “Y” on the top of the dark colored head.

Fall armyworms are a tropical insect species. As such, only southern Florida and southern Texas afford mild enough wintertime temperatures to assure their survival. In fact, fall armyworm activities are continual in overwintering areas. Of course, fall armyworms also overwinter in their native ranges of Mexico, Central America and South America. Seasonal fall armyworm activities in non-overwintering areas begin with egg-laying activities of the moths moving northward out of their native ranges. Once established, additional generations can occur every 23-25 days. Thus, in central Texas, they experience 7 generations of fall armyworm each year, while in Kansas, 2-4 is a more likely number, and depends on when initial flights moved into Kansas.

Female fall armyworm moths have the ability to produce approximately 1000 eggs which they deposit in clusters containing up to 400 eggs each. Larvae produce a silken thread which allows them to drop or be blown to their food source

Smaller larvae will do superficial feeding, while larger larvae cause more extensive damage. Damaged grasses may become withered and brown. Under large populations, the appearance of “browned areas” occurs in very short order (24-hours or less). However, fall armyworms seldom kill grass —- rather, than nubbing a plant down to the crown and growing point, larvae will select a more tender adjacent grass blade to feed upon. Of course, under heavy feeding pressure, larvae may be forced to feed deeper down on a plant, but usually, when the food supply becomes scarce or “tough”, the larvae will move “in mass” to adjacent areas where there is a “fresh stand” of food to feed on. Thus, having moved on and given that they usually do not “eat plants into the ground”, a flush of new growth restores the appearance of the turf. Rain and/or irrigation will help to speed up the regrowth process.

If insecticide applications are considered, cyhalothrin (Spectracide Triazicide), permethrin (38 Plus Turf, Termite & Ornamental Insect Spray; Hi-Yield Garden & Farm Insect Control; Eight Yard & Garden RTS) and spinosad (Conserve, Monterey Garden Insect Spray, Captain Jack’s Dead Bug Brew, Natural Guard Spinosad) and Dylox (BioAdvanced 24-Hour Grub Control) are commonly available materials registered for control of fall armyworm in turf. Spray treatments have greater and quicker contact efficacy than granular applications. Granular treatments require irrigation or rain to activate the insecticide from the dry granular carrier. Professional lawn care service personnel have access to additional materials (such as Scimitar and Deltamethrin) which may have more persistence than homeowner products.

1712 Claflin, 2021 Throckmorton Plant Science Center
Manhattan, KS 66506 (785) 532-6173

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VIDEO OF THE WEEK:
Season Extension in the Vegetable Garden
(K-State Garden Hour)
Ready or not, cold weather is coming. Learn how to extend your growing season with various techniques.

GARDEN TO-DO
Fertilize cool-season lawn (KY bluegrass or tall fescue)
Dig gladiolus when foliage begins to yellow & air dry before storing
Buy spring-flowering bulbs. Plant in late September through October
TURF
Timing Lawn Seeding
September is the time to reseed cool-season lawns, such as tall fescue and Kentucky bluegrass. For Kentucky bluegrass, finish reseeding by early October. The last day to safely reseed tall fescue is considered October 15.

With a late seeding, take special care not to allow plants to dry out. Anything that slows growth will make it less likely that plants will mature enough to survive the winter. Seeding after the cut-off date can work, but the success rate goes down the later the planting date. Late plantings often fail as a result of poorly rooted plants being heaved from the soil after repeated freezing and thawing. Roots are then exposed and quickly dry out. Help the seedlings establish a healthy root system prior to freezing weather by keeping them watered well.

VEGETABLES
Harvesting Sweet Potatoes
Cold soil negatively affects the quality of taste and shelf life of sweet potatoes. To prevent this, harvest prior to the first fall freeze. Sweet potatoes are typically ready for harvest three to four months after planting.

Gently unearth the sweet potatoes in one mound to check for readiness. You may notice die-back of the above ground growth as harvest time approaches. After digging, sweet potatoes need to be cured for several days. This process increases the shelf-life and flavor of the sweet potatoes. Curing should be done in a warm, humid location. Ideally the temperature should be between 85- and 90-degrees F with a relative humidity between 85 and 95%.

Store sweet potatoes for several weeks before consuming. During this time starches are converting to sugars which improves the flavor. Protect sweet potatoes during storage by keeping temperatures above 55 degrees F.

Vegetable Crop Rotation
Success in the garden requires planning. To give your plants a healthy start next year, the best practice is to rotate crops within the same family to a different location than where they’re growing this year. This is known as crop rotation and offers several benefits.

Plants in the same family are typically susceptible to similar pests. Some pests overwinter in the soil; some are able to survive on debris. If the same host is available when the pests emerge in the spring, they will be able to continue feeding and multiply the problem. Crop rotation breaks the cycle of these pests.

Plants in the same families have similar nutrient requirements. Rotating crops prevents the soil from becoming depleted of those nutrients. Also, the varied root system depths from one plant family to the next contributes to the health of the soil.

Now is the perfect time to make a map of the vegetable garden so you can switch things up when you plant next year. For example, in the location where tomatoes are growing now, avoid planting anything from the Solanacaeae family (eggplant, pepper, potato) next year.

The Kansas Garden Guide has a helpful table of common vegetable crop families and an example of how to rotate these crops. You can access a digital copy of the Kansas Garden Guide here: https://bookstore.ksre.ksu.edu/pubs/kansas-garden-guide_S51.pdf

PESTS
Lace bugs
Description: Adult lace bugs are 1/8 to 1/3-inch long with lace-like wings. Their bodies are lightly colored and have dark markings. Nymphs do not have wings, are darker than adults and have an oval-shaped body. Nymphs leave behind exoskeletons when they molt. These can be seen attached to plant foliage. Small, dark droppings are deposited on undersides of leaves by adults and nymphs. Eggs are small and black and can also be found on the underside of leaves.
Life Cycle: Lace bugs have two generations each year. Adults overwinter under tree bark or in plant debris on the ground. As plants leaf out in the spring the adults begin feeding and lay eggs which hatch within two weeks. The nymphs feed for several weeks as they molt, mature into adults and lay the next generation of eggs. This generation feeds through summer and into fall.
Damage: Lace bug damage is often seen on oak and sycamore trees in our area. Some other hosts include: hawthorn, pyracantha and cotoneaster. Adults feed on leaves using a piercing mouthpart. This creates a stippled look on the leaf which can result in discoloration and premature drop if the infestation is heavy.
Control: Control measures are not recommended at this time of year. Trees and shrubs have adequately stored food for the winter so lace bugs will not negatively affect an otherwise healthy tree/shrub at this point in the season. Natural predators, such as green lacewings, spiders and others, prey on lace bugs as well so any treatment used should be carefully selected to avoid harming this population. Spraying infested plants with a strong force of water can dislodge lace bugs.

Read more: Lace bugs (KSRE Publication)

MISCELLANEOUS
Garden Spiders
The two spiders we commonly see in the garden during the day are the yellow garden spider and banded garden spider. The yellow garden spider has a black abdomen with yellow markings and black legs with a yellow or red band. The banded garden spider has continuous bands across the abdomen and legs. Alternating white and dark bands cover the abdomen and the bands on the legs are orange and black.
Both spider varieties weave large webs to trap their prey. The insects they feed on include ones that can damage plants in the garden and landscape. These spiders are actually beneficial to gardeners and should be left alone to help control the pest population.
QUESTION of the WEEK
Ornamental Sweet Potatoes
What should I do with my ornamental sweet potatoes? Are their roots edible?

Ornamental sweet potatoes are prized for their foliage. The plants are bred for their aesthetic value so although the roots are edible, they tend to be bitter. If you choose to consume them, follow the curing instructions detailed above.

Ornamental sweet potatoes are grown as annuals in Kansas, but can be overwintered by digging them just before the first frost and storing until it’s safe to plant in the spring. Remove the above ground growth and keep the roots in moist compost in a cool, dark room.

Alternatively, the entire plant can be moved indoors and kept as a houseplant during the winter. Check the plant first for signs of disease or pests. Cut the vines back to about one-foot and carefully transplant into the desired container. Keep the plant in an area with plenty of natural light until warmer weather returns in the spring.

Contributors:
Cynthia Domenghini, Instructor and Horticulture Extension Specialist
Raymond Cloyd, K-State Entomology

Division of Horticulture
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
(785) 532-6173

For questions or further information, contact your local extension agency.
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K-State Research and Extension is committed to making its services, activities and programs accessible to all participants. If you have special requirements due to a physical, vision or hearing disability, or a dietary restriction please contact Extension Horticulture at (785) 532-6173.

Cynthia Domenghini, Ph.D.
Instructor; Horticulture Extension Specialist
Department of Horticulture and Natural Resources
Kansas State University
1712 Claflin Rd.
Manhattan, KS 66503
785-340-3013
[email protected]

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