Do part to clean landscapes, fight mosquitoes

Hurricane cleanup by local governments continues throughout the area and though it may not seem important in the overall scheme of things, homeowners are asked to do their part by cleaning their outdoor landscapes.

High winds blew a lot of leaves off trees. These leaves filled home gutters, street gutters, subdivision drains, and drainage outlets and ditches. Help reduce the threat of West Nile virus carrying mosquitoes by clearing hurricane-strewn debris. Standing water will breed new mosquitoes increasing the threat of more West Nile illness.

Cut or mow overgrown vegetation to allow sunlight to dry the soil. Empty containers that hold water and turn them over so they can’t fill with the next rain. Drain low spots in the yard and areas that hold water and remain overly damp for several days. Clean house gutters, which also will help prevent the fascia from rotting. And clean street gutters so water can freely flow to the storm drains. Purchase larvacidal briquettes to use in fishponds, rain barrels or rain gardens that can’t be emptied.

West Nile virus, the mosquito-born, flulike illness, will remain a threat until the days start cooling off and getting shorter. Older people and people with suppressed immune systems are particularly vulnerable to the disease, but it has seriously sickened some healthy people, too. About 1 in 5 of those exposed to the virus through a mosquito bite will show symptoms, but most of those will be minor. Many people assume they have a summer cold or flu and will go undiagnosed.

Adult mosquitoes prefer to rest in moist, shady areas such as dense vegetation during the daytime. Consequently, homeowners should remove tall weeds and overgrown vegetation from their yards. To further reduce intolerable levels of biting adult mosquitoes, residual insecticides can be applied to shrubs, hedges and other shaded areas, such as under decks and along foundations.

Homeowners opting to try this themselves should use lawn and garden insecticides containing permethrin (Ortho Mosquito B Gone, Spectracide Mosquito Stop), cyfluthrin (Bayer Advanced Powerforce Mosquito Killer), bifenthrin (Ortho Home Defense Max), or lambda cyhalothrin (Spectracide Triazicide). A hose-end sprayer is usually most effective for making such applications.

Repellents will help prevent bites when spending time outdoors. Traditionally, the most effective mosquito repellents contain the active ingredient DEET, ranging from 5 percent to 40 percent. Higher percentages of DEET in the ingredients provide longer protection. Low percentage formulations (10 percent or less) are suitable for shorter periods outdoors (one to two hours), and are recommended for use with young children.

Earlier this year, two new mosquito repellents were registered by the U.S. Environmental Protection Agency and recommended as alternatives to DEET by the Centers for Disease Control and Prevention. Picaridin (7 percent Cutter Advanced) and lemon eucalyptus oil (30 percent Repel Lemon Eucalyptus) provide relief for about two to four hours. Unlike DEET-based repellents, picaridin is essentially odorless, and lemon eucalyptus oil has a lemon scent. For many people, the new products will also have a more pleasing feel on the skin. These may not yet be available on retail shelves.

Citronella oil does have mosquito-repelling properties and the scented candles can provide some protection. For maximum effect, use multiple candles placed close (within a few feet) of where people are sitting. A single candle located at the center or edge of a picnic blanket probably will not provide much benefit other than atmosphere. Mosquito-repellent plants, garlic, and other oft-advertised botanical products generally are ineffective.

Don’t give up

Forlorn flower beds past their prime and overrun with weeds are an all-too-familiar sight in late summer landscapes. Our long growing season and abundance of insect and disease problems generally make it unreasonable to expect all bedding plants to hold up from the beginning of summer in early May until its end. Unfortunately, many gardeners give up with the attitude that it is too hot to plant anything now anyway, and allow their beds to remain unattractive eyesores in the landscape.

Nurseries are still well-stocked with colorful, heat-tolerant bedding plants that will grow vigorously from now through late October or early November, when we will plant cool-season bedding plants. And you can work in the cooler times of the day when it’s not so hot.

When planting late in the growing season, choose well-established plants in 4-inch or larger pots. Make sure the plants you purchase are healthy and vigorous and have been properly cared for. Start off with the highest quality plants you can find.

Be careful to plant the bedding plants at the proper depth. The top of the root ball should be level with the soil of the bed. Planting transplants too deep makes them more susceptible to root rot or crown rot. The fungal organisms that cause these diseases are very active in the moist, hot weather of late summer, so make sure plants are not planted deeper than recommended.

When planting is finished, mulch with an inch or two of your favorite mulch and water the bed thoroughly. Watering is the trickiest part of planting this time of year. You may need to water the bed fairly frequently until the plants send roots out into the surrounding soil. Watch the plants carefully for wilting, and water when needed.

You have lots of choices for planting now. For sunny beds or containers, choose periwinkle, melampodium, blue daze, purslane, portulaca, pentas, torenia, perennial verbena, salvias, sun-tolerant coleus, lantana, zinnia, marigold, abelmoschus, globe amaranth, cosmos, balsam and celosia. For shady and partly shady beds and containers, choose impatiens, begonias and coleus.

Got a gardening question? Write to Bob Souvestre, horticulturist with the LSU AgCenter, at Burden Center, 4560 Essen Lane, Baton Rouge, LA 70809, or email to [e-mail], or call Master Gardeners at [phone].