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IPM: a sensible, knowledgeable approach to managing landscape pests

By now you realize that as you venture into your landscape, you’re not alone. Yes, it’s a jungle out there. Like the characters of  Wizard of Oz trudging into the dark forest, you may be chanting “Aphids and borers, and mites, oh my!” Sure, we share our shrubs and trees with a wide assortment of insects, diseases, viruses, and bacteria. Some of these pests are as fond of your newly plahibiscus and beented crapemyrtle as you are. Fortunately, some pests are fodder for helpful, beneficial critters that feast on them, thereby protecting our shrubs and trees.

When you encounter pests in your landscape, deal with them sensibly. Avoid the typical knee-jerk response to apply a pesticide to vanquish the pest. After all, you may end up killing beneficial insects and as the saying goes, “kill a beneficial insect and you inherit its job.” To manage pests this year, follow a game plan that involves knowledge and common sense. It’s called Integrated Pest Management or IPM for short. It’s a decision-making process that involves the following four components:

  1. Monitor your landscape for the presence of harmful and beneficial organisms. Inspect your shrubs and trees on a regular basis. Examine them for signs and symptoms of pests. Generally, most plants have few problems if they are planted in the right location and receive proper care.

While examining your plants for problems, check them for beneficial insects–the arch enemies of insect pests.  Beneficial organisms consist of predators, parasites, and diseases. Predators kill and eat their prey. Parasites live in or on their prey, feeding on its tissues and eventually killing it.   Beneficial pathogens consist of a variety of viruses, fungi and bacteria that naturally infect and kill harmful pests.

By monitoring the garden and landscape, you have more options for controlling pest problems when you detect them early

  1. Identify harmful and beneficial organisms.Determine if the pest has the potential to cause cosmetic or health damage. To help you ID beneficial insects in your landscape, see Beneficial Insects, Butterflies, and More Around the Home and Garden.
  1. Evaluate the extent of the pest problem and decide if pest management tactics are warranted. While it’s difficult at times to accept any kind of plant damage, some is just cosmetic and poses no real harm to the plant. For example,  fall webworms and gall-forming insects are common pests that produce unsightly webs and galls, but do not necessarily threaten the health of the plant.Southern pine beetles, on the other hand, demand immediate action when a tree exhibits signs of an infestation. Southern pine beetle-infested trees need to be felled and  removed quickly to suppress outbreaks that will afflict nearby pines.
  1. Choose appropriate control measures. Try cultural and mechanical controls first. A cultural approach could be proper watering and fertilizing to help shrubs and trees cope with or outgrow the injury. Mechanical controls involve handpicking insects and discarding them in a jar of soapy water, dislodging them from tree branches with a strong spray of water from the hose, or pruning out heavily infested or infected shoots.

Consider a pesticide only as a last resort: when pest levels have reached damaging levels and your other tactics have not been successful. Use pesticides sparingly to control the targeted pest. Before purchasing and using any pesticide, read the label and follow all directions and precautions.

Keep in mind that healthy landscapes have a wide variety of beneficial creatures as well as a tolerable levels of damaging critters. With IPM you work with Mother Nature to maintain this balance while keeping harmful pests at bay.

© Bob Polomski 2015

Snowfall in Spring? Must be annual trampweed

Annual trampweed (Facelis retusa), is a winter annual, common throughout South Carolina, especially in dry sandy
fields, roadsides, lawns, pastures, and waste places.   This winter annual is a member of thefacelisretus aster family which is an introduced South American weed that’s common in lawns and roadsides.  This weed is a poor competitor, but it will thrive in the most inhospitable environments: dry, infertile, sunny, environments.  When the preferred turfgrass is
absent or growing poorly (this spring dry spell has slowed down the growth of a number of grasses), expect this weed to thrive and reproduce.Obviously, the best way of controlling this wintfacelisretusaer annual is to improve the health of the lawn with proper fertilization (based on soil test results), proper mowing height and frequency of mowing, etc. A healthy lawn will out compete this annual weed for light, water, and nutrients.

For information on Annual Trampweed, see HGIC 2319 (http://www.clemson.edu/extension/hgic/pests/weeds/hgic2319.html).

Wild garlic are blemishes in the winter lawn.

Wild garlic and wild onion are two common lawn and garden weeds that are a lot like teenage acne:  they appear where you don’t want them and, in some folks, cause lots of anxiety and concern.  At this time of year these weeds look like green splotches on the beautiful brown canvas of dormant centipede and bermudagrass lawns.wild garlic 1

Wild garlic (Allium vineale) is a herbaceous bulb that was probably introduced to the U.S. from Europe by early settlers in the early 1700s.  This cool-season weed appears in the fall and matures and dies down in late spring.  Wild garlic reproduces primarily by above- and below-ground bulbs.

Wild onion (A. canadense) is not as common as wild garlic in our state.  Unlike wild garlic which has hollow leaves and greenish-white flowers, wild onion has flat, solid leaves and pink flowers.
wild garlic 2
Wild garlic and wild onion pose no harm to your lawn.  However, you may find it unsightly.  If these weeds have invaded your landscape, there are a few things you can do.
1.  Do nothing.  Once your dormant lawn turns green and the wild garlic and wild onion begin to dieback, you will forget about them until next fall when they will reappear.  Some people feel uncomfortable with the “do nothing” approach.  In fact, they feel as if something should be done for the neighbors’ sake.  O.k., then, here’s what you do.  Since wild garlic looks so much like cultivated onions, tell your neighbors that you’re growing fancy French scallions in your lawn.  Yeah, tell them that they make their best growth in the lawn, especially when they’re planted in random, haphazard rows .  Who knows, maybe a neighbor or two will believe you.

2.  Spray-paint the wild garlic brown to match the color of your dormant lawn.  Hey, if women can get away with using cosmetics to hide a few blemishes on their faces, you should be able to camouflage the clumps of wild garlic in your lawn.
3.  Pull them out by hand.  Pick a day when the soil has been moistened by a nice, soaking rain.  With a flat-headed screwdriver, loosen up the soil around a clump of wild garlic.  Then, grab the base of the weed and slowly tease it out of the ground.  Since wild garlic produces a bunch of underground bulblets, try to lift them all of them out.  I do it bare-handed because I love the heavenly aroma of garlic.
4.  Apply a herbicide.  Wild garlic is difficult to control with herbicides because it produces several bulblets that do not sprout all at once.  Some bulblets will sprout one year and others will not emerge until the following year; therefore, it can take 2 or 3 years for a postemergence herbicide to control the entire plant.  An effective herbicide for controlling wild garlic and wild onion are the “three-way” types that contain 2,4-D, MCPP, and dicamba (such as, Weed-B-Gon® and Trimec®).  Treat wild garlic and wild onion now–in late November to December, which is when they’re most susceptible to herbicide applications.

If necessary, make a followup application in late February or early March.  Please read and follow the label directions when using any pesticide.

If wild onions and wild garlic are growing in your flower borders or among your azaleas and other shrubs, refer to approach #3.
Fortunately, we’ll lose sight of wild garlic and wild onion in late Spring.  At that time, no one will know if you accepted or got rid of these blemishes.

Mistletoe: friend or foe?

In last Sunday’s paper the following ad caught my eye: “Real, Fragrant Mistletoe Shipped Direct To You From the Mountains of Oregon.” I looked at the festive sprig of green leaves and pearly white berries secured with a bright red bow and smiled. I’v got plenty of mistletoe right outside my front door, thank you. Now that the oaks have shed their leaves, I can see green azalea-sized clusters of mistletoes (Phoradendron serotinum) nestled comfortably in the bare branches.

It’s interesting how this native parasitic plant comes into its own during the holiday season. For whatever the reasons, it has remained in our culture for centuries.

The modern tradition of using mistletoe around the Christmas holiday season dates back to the Celts of northern Europe. Druids, the holy men of Celtic society, used mistletoe in winter solstice ceremonies. Fearing the cold, short days of winter, the Druids used this green symbol of growth to ensure the return of the sun’s warmth in the spring.

Some cultures associated mistletoe with fertility because of its ability to bear fruit in winter. The Ainu of Japan chopped-up mistletoe leaves and sprinkled them on their fields to ensure a good crop. In Austria, a sprig of mistletoe was placed in a couple’s bed to encourage conception.

Of more modern origin is the act of kissing under the mistletoe on Christmas Eve. It probably drew upon age-old rituals and traditions involving druidism and fertility rites. In any event, it began as a fad in England and Wales in the 18th century and has become a Christmas tradition in many households today.

As a horticulturist, I’m intrigued by this half-parasitic plant. Mistletoe has leaves to produce its own food, but steals water and nutrients from its host. Mistletoe begins its life as a small white berry that is eaten and spread by birds, such as robins, thrushes, and cedar waxwings. The seed germinates within 6 weeks after being deposited by a bird on twigs and small branches. It produces “roots” that tunnel through the bark and tap the inner tissues for water and nutrients. Shortly thereafter, the seedling produces shoots and leaves. It takes about 5 years for mistletoe to flower, which occurs in the fall. Yellowish-green male and female flowers are borne on separate plants. After being pollinated by wind or insects, the female flowers give rise to berries that ripen in the winter to begin the cycle again.

For the past few weeks I’ve answered a flurry of calls from residents wanting to know if those green clumps will harm their trees and how they can be removed.

Mistletoe is a pest that can affect the growth and vigor of its host, and can expose the tree to attacks by diseases and insects. In some instances, mistletoe can cause branches to die back, and heavy, shrubby mistletoes can break entire limbs. In other situations, mistletoe is simply a cosmetic problem, which only affects the appearance of the tree.

The only effective way of ridding your tree of a mistletoe infestation is by pruning. Cut the infected limb one to two feet below the plant because mistletoe “roots” may extend up to a foot on either side of the point of attachment. Breaking off the tops, similar to plucking off the leaves of dandelions or wild garlic in the lawn, only encourages regrowth. Obviously, pruning out mistletoe clumps from the uppermost reaches of trees should be left in the hands of certified arborists. If you’re a do-it-yourselfer, please avoid butchering the tree with haphazard cuts.

Since the 1950s, scientists have been searching for cheaper and more effective methods of controlling mistletoe. Herbicides have been evaluated, but they may pose a threat to the host. Growth hormone sprays, such as ethephon (Florel® Brand Fruit Eliminator), interrupt flowering or cause the shoots to fall off, but the mistletoe eventually resprouts and needs to be treated again.

If you decorate your home with store-bought or home-grown mistletoe, hang it up high out of the reach of children and pets. The berries are toxic and the sap may irritate the skin of some people. Watch out…it also can turn Scrooges into smoochers.

Bob Polomski (C) 2014

Insecticidal soap vs. dishwashing liquid

On the radio last week a caller read the label of an insecticidal soap over the phone, and wondered about the ingredient: “potassium salts of fatty acids?” The caller also wanted to know if dishwashing liquid could be used as a substitute for insecticidal soap.

I explained to the caller that these potassium salts of fatty acids are created by adding  potassium hydroxide to fatty acids obtained either from  animal fat or in plant oils. The resulting “soap salts” are most effective in controlling  soft-bodied pests such as aphids, scale and mealybug crawlers, thrips, whiteflies, and spider mites. Generally, they have little effect on beetles and other hardbodied insects (an exception being cockroaches). The soaps must come into direct contact with the pest to be effective.  The soap penetrates the outer cuticle of the insect’s body and dissolves or disrupts the cellular membranes causing dehydration and death.  Soaps can also block the spiracles or breathing pores in the insect’s body which interferes with respiration. In some cases soaps may also act as an insect growth regulator, affecting the metabolism of cells and metamorphosis.

Certain common dishwashing liquids and laundry detergents when mixed with water have also shown insecticidal and miticidal properties. When applied to an assortment of vegetable crops, Palmolive®, Dawn®, Joy®, Ivory®, and Dove®, for example, have effectively reduced populations of whitefly , aphids, and spider mites. However, dishwashing and laundry detergents are not labeled as insecticides. Although they may be insecticidal, they are chemically different from  the registered insecticidal soaps.  Furthermore they may prove phytotoxic, causing injury by dissolving the waxy cuticle of the plant’s leaf surface. I told that caller that it’s better to save these soaps or the washing of clothes and cleaning of dishes for which they were designed.

‘Tis the season for mistletoe

MistletoeIn last Sunday’s paper the following ad caught my eye:  “Real, Fragrant Mistletoe Shipped Direct To You From the Mountains of Oregon.”  I looked at the festive sprig of green leaves and pearly white berries secured with a bright red bow and smiled.  I’ve got plenty of mistletoe right outside my front door, thank you.  Now that the oaks have shed their leaves, I can see green azalea-sized clusters of mistletoes (Phoradendron serotinum) nestled comfortably in the bare branches.

It’s interesting how this native parasitic plant comes into its own during the holiday season.  For whatever the reasons, it has remained in our culture for centuries.

The modern tradition of using mistletoe around the Christmas holiday season dates back to the Celts of northern Europe.  Druids, the holy men of Celtic society, used mistletoe in winter solstice ceremonies.  Fearing the cold, short days of winter, the Druids used this green symbol of growth to ensure the return of the sun’s warmth in the spring.

Some cultures associated mistletoe with fertility because of its ability to bear fruit in winter.  The Ainu of Japan chopped-up mistletoe leaves and sprinkled them on their fields to ensure a good crop.  In Austria, a sprig of mistletoe was placed in a couple’s bed to encourage conception.

Of more modern origin is the act of kissing under the mistletoe on Christmas Eve.  It probably drew upon age-old rituals and traditions involving druidism and fertility rites.  In any event, it began as a fad in England and Wales in the 18th century and has become a Christmas tradition in many households today.

As a horticulturist, I’m intrigued by this half-parasitic plant.  Mistletoe has leaves to produce its own food, but steals water and nutrients from its host.  Mistletoe begins its life as a small white berry that is eaten and spread by birds, such as robins, thrushes, and cedar waxwings.  The seed germinates within 6 weeks after being deposited by a bird on twigs and small branches.  It produces “roots” that tunnel through the bark and tap the inner tissues for water and nutrients.  Shortly thereafter, the seedling produces shoots and leaves.  It takes about 5 years for mistletoe to flower, which occurs in the fall.  Yellowish-green male and female flowers are borne on separate plants.  After being pollinated by wind or insects, the female flowers give rise to berries that ripen in the winter to begin the cycle again.

For the past few weeks I’ve answered a flurry of calls from residents wanting to know if those green clumps will harm their trees and how they can be removed.

Mistletoe is a pest that can affect the growth and vigor of its host, and can expose the tree to attacks by diseases and insects.  In some instances, mistletoe can cause branches to die back, and heavy, shrubby mistletoes can break entire limbs.  In other situations, mistletoe is simply a cosmetic problem, which only affects the appearance of the tree.

The only effective way of ridding your tree of a mistletoe infestation is by pruning.  Cut the infected limb one to two feet below the plant because mistletoe “roots” may extend up to a foot on either side of the point of attachment.  Breaking off the tops, similar to plucking off the leaves of dandelions or wild garlic in the lawn, only encourages regrowth.  Obviously, pruning out mistletoe clumps from the uppermost reaches of trees should be left in the hands of certified arborists.  If you’re a do-it-yourselfer, please avoid butchering the tree with haphazard cuts.

Since the 1950s, scientists have been searching for cheaper and more effective methods of controlling mistletoe.  Herbicides have been evaluated, but they may pose a threat to the host.  Growth hormone sprays, such as ethephon (Florel® Brand Fruit Eliminator), interrupt flowering or cause the shoots to fall off, but the mistletoe eventually resprouts and needs to be treated again.

If you decorate your home with store-bought or home-grown mistletoe, hang it up high out of the reach of children and pets.  The berries are toxic and the sap may irritate the skin of some people.  Watch out…it also can turn Scrooges into smoochers.

Aphids and mites and orange-striped oakworms , oh my!

By now, many of us have gotten used to the heat and humidity—or at least have become accustomed to it.  However, when it comes to insect pests, few gardeners ever get used to them.  Well, friends, the months of August and September are the heyday for insects.  Over the course of the summer their numbers have rapidly increased, so expect to see a multitude of six-legged critters out there.

When you have an insect-encounter, avoid the credo of some gardeners that “the only good bug is a dead bug.”  Not all insects are harmful.  In fact, beneficial insects handily outnumber harmful pests.  Beneficial insects are the natural enemies of harmful or damaging insects and can be divided into two main categories:  predators and parasites.

Predators hunt and feed on other insects.  They include praying mantids (the Carolina mantid is the official state insect of South Carolina), lady beetles, lacewings, and assassin bugs.

Parasites hatch from eggs inside or on another insect and they eat their host insect as they grow.  Perhaps you’ve seen the white cocoons adorning the body of a tomato hornworm.  Inside the cocoons are braconid wasp larvae that fed on the innards of the caterpillar and now are a step away from changing into adult wasps.

Releasing beneficial insects into your landscape or garden may help, but it’s better to conserve the beneficial insects already there by managing harmful pests with knowledge and good sense. Here’s how:

1.Watch for and learn to identify pests.  At least once a week walk through your landscape and examine your plants for pests.  Learn to distinguish between the harmful and helpful insects in your garden and landscape.  Check out the colorful fact sheet titled “Beneficial Insects” at the Clemson University  Department of Entomology web site at http://entweb.clemson.edu/cuentres/eiis/bbam/bbam.htm.  If you spot an insect and are unable to identify it, take a sample to your Clemson Extension office.

2. When trouble strikes, turn to nonchemical controls first.  Insects such as aphids and spider mites can be hosed off with a strong spray of water, others such as Japanese beetles and orangestriped oakworm caterpillars can be handpicked.

3. Sometimes it is necessary to resort to more potent but least toxic measures such as insecticidal soap or the botanical insecticide neem to control soft-bodied insects, such as aphids and mites.

4. Occasionally you may have to turn to more potent pesticides, especially when you feel the damage is more than you or your plants can tolerate.  Consider spot-treating heavily infested plants instead of making a blanket application that can destroy beneficial insects.  Use recommended pesticides and apply according to label directions.  Foraging honeybees and other pollinators are sensitive to these insecticides, so treat the plants in early morning or late evening when no bees are present.

To attract and maintain beneficial insects in your garden, grow a variety of flowering plants that bloom from early spring through fall.  While the larvae generally feed on insects and mites, adults feed on nectar and pollen—either exclusively or to supplement their diet when insects or mites are in short supply.  So feel free to add more color and beauty to your garden with yarrows, daisies, and sedums.  As I tell my wife who occasionally questions my purchases, I’m doing it for the beneficial insects—a gardener’s best friends.