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Chicory
Cichorium intybus

IDENTIFICATION — The line between wildflower and weed can be narrow. With chicory, or blue sailor weed as it’s sometimes called, what one person considers a lovely blue flower, a neighbor might consider a weed. This is one of those perennials that can go either way.

In summer, branched flower stems spring up from the center of a low rosette of leaves that looks very much like a dandelion. These tough stems can reach more than 7 ft. tall, but the average is usually less than 3 ft. The leaves along the tough stems are small and not very noticeable. Underground there’s a fleshy taproot that if broken, will “bleed” a milky white sap. But the daisylike flowers (usually blue, but sometimes pink or white) are what you’ll notice first.

Each morning the flowers open facing the rising sun. They last just one day, so by late afternoon they fade and wither. But rest assured there will be more tomorrow morning.

You can eat tender young chicory leaves in salads or as a cooked green. Roots are cooked and eaten or dried and ground to make a coffee substitute.

FAVORITE CONDITIONS — This European native has naturalized across much of North America. You’ll spot it growing along roadsides or the edge of your garden. It does not like areas that are frequently cultivated or mowed to less than 2 in. tall.

CONTROL — Just like a dandelion, chicory spreads mainly by seeds, so you’ll want to keep it from setting seeds. However, pieces of root will also grow quite easily. Repeatedly mowing the plant short, or cutting it off at the soil line will eventually kill it. The taproot is hard to pull from the ground, even after soaking the area with water first. Broadleaf or non-selective herbicides are also effective at getting rid of chicory.

Click to see a larger image.

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Rose slug sawfly
Endelomyia aethiops

IDENTIFICATION — Smooth, translucent pale-green larvae could attack the leaves of your roses next May and June.

DAMAGE — Feeding on the surface of the foliage between the veins, larvae create a window-pane look. Leaves turn brown and curl. Large infestations may stunt the plant’s growth.

CONTROL — Prune out or handpick small populations. On cloudy days (so you don’t burn the leaves) in early summer, spray all plant surfaces with Safer^® insecticidal soap or horticultural oil to smother younger larvae. These controls don’t work as well on older larvae, but most of the damage has already been done by then.

If there are so many larvae that the plants stop growing and blooming, dust the affected plants with an insecticide containing carbaryl, such as Sevin^®. Or dilute and spray spinosad on all leaf surfaces in early summer. And all season, pick up debris and leaves from around plants to remove any larvae that may be hiding there.

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Fuller’s teasel
Pastinaca sativa

IDENTIFICATION — Originally introduced from Europe for use as a dried flower, Fuller’s teasel has naturalized in much of North America. The first year, this biennial forms a rosette of oblong leaves that may grow to nearly 12 in. long. During the second year, several flower stalks with spines shoot up nearly 6 ft. The spiny egg-shaped lavender flowers bloom from June to October. After flowering and producing seed, the plant dies.

FAVORITE CONDITIONS — Fuller’s teasel prefers open, sunny sites like roadsides and disturbed areas, although it may grow in your lawn or garden. It’s a particular pest for restored prairies and wildlife areas because each plant is capable of producing more than 2,000 seeds and most of them will germinate. Under favorable growing conditions, it can actually outcompete native prairie plants.

CONTROL — As with all biennial weeds, it’s easier to manage Fuller’s teasel in the rosette stage. Use a dandelion-puller to pull out the long tap root or slice it off, below the soil, with a sharp spade. And as with dandelions, be sure to get as much of the root as possible so it won’t resprout. You can cut off the flower head to prevent it from going to seed. Herbicides that contain triclopyr or glyphosate can also be used, but are most effective when applied while the plants are in the rosette stage before they flower.

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Wild parsnip
Pastinaca sativa

IDENTIFICATION — This invasive biennial is related to the edible parsnips you may grow in your vegetable garden. Like its cultivated cousin, wild parsnip has a long, white-yellow taproot that is edible.

The first year, a rosette of leaves emerges and grows to about 1 ft. tall. Egg-shaped leaflets are in pairs along the stem and are deeply toothed or lobed. During the second year it sends up a thick, grooved flower stalk. Bright yellow flowers in flat clusters, like dill, appear from May to October. Flowering plants may grow as tall as 5 ft.

FAVORITE CONDITIONS — Wild parsnip spreads by seed and grows just about anywhere in North America in fields, ditches, prairies, bike paths, cultivated gardens and even your lawn. Although it prefers full sun and moist to wet soils, it will grow in shade and dry soils, too.

CONTROL — Hand digging wild parsnip is the most effective control method. But the deep taproot can make it difficult. If possible, identify and dig up plants when they’re in the rosette stage and the tap root is short and easier to dig. Cut or mow flower stalks on mature plants to prevent seeds from forming. Then dig up as much of the plant as you can. Herbicides that contain glyphosate, such as RoundUp^®, can be an effective control. Follow label directions. Wear long sleeves, pants and gloves when handling wild parsnip because it exudes a chemical that causes photodermatitis blisters when your skin is exposed to sunlight. These can become very painful and may require medical attention.

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Pillbugs and sowbugs

IDENTIFICATION — Here are two bugs that look almost identical — pillbugs and sowbugs. The only difference seems to be that pillbugs roll into a ball when they’re frightened. Both go by many different names, such as roly-poly and wood lice. And they’re really not bugs at all — they’re crustaceans — they’re more closely related to crabs and lobsters. Adults can grow to 3/8 in. long.

DAMAGE — These bugs don’t really harm plants unless there are so many that the creatures need the food. Then they’ll feed on fine roots and stems of tender seedlings. Usually they’re scavengers, feeding on decaying plant material and hiding in dark, damp areas.

CONTROL — There’s no urgent need to control either one. But if you feel overrun, take away the critters’ hiding places. Remove dead plant material to the compost pile, get rid of boards and lift pots off the ground. These are some of their favorite spots.

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Flea beetle
Melittia cucurbitae

IDENTIFICATION — Young leaves of vegetables and flowers riddled with “shot” holes are a sign that flea beetles may be attacking your garden.

These small, black insects aren’t really fleas, but they jump like them. Although there are several species, damage and identification are the same.

DAMAGE — Adults chew round holes in the leaves, especially those of young plants, and on tender new growth. Foliage pierced with holes dries out quickly and dies. Flea beetle larvae sometimes feed on plant roots.

CONTROL — Adult flea beetles live over the winter in the soil and in debris. By cleaning up the garden in the fall, you’ll eliminate some of their hiding places.

Because they can produce a few generations each year, it’s important to get control of a population first thing in the spring. Protect young plants with spun-fabric row covers. Or, once you begin to notice damage, spray with neem oil or insecticidal soap every week or so.

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Common mallow
Malva neglecta

IDENTIFICATION — Common mallow is a relative of hollyhocks that produces pink, pale blue or white summer flowers. It is sometimes called cheeseweed because the seed pods that follow the blooms are shaped like segmented wheels of cheese. These pods turn brown in summer and split open to release seeds.

FAVORITE CONDITIONS — In full sun to light shade and moist soil, common mallow can sprout in fall or early spring, producing flowers and seeds the following summer.

CONTROL — This weed has a short taproot, which makes it easy to pull or hoe.

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Squash vine borer
Melittia cucurbitae

IDENTIFICATION — There’s nothing worse than having your squash die on the vine because of squash vine borers. Adult moths are about 5⁄8 in. long with translucent wings. They have an orange and black striped body with fringed hind legs. Females emerge in spring to lay pinhead-sized eggs on the lower 3 to 4 ft. of squash vines.

Once the eggs hatch, the larvae bore into the stem and start eating. They grow up to an inch long with a white body and brown head. Larvae live and eat in the vine for four to six weeks, then move from the plant into the soil, where they spend the winter in a cocoon.

DAMAGE — Squash, zucchini, pumpkins and gourds are all susceptible to attack by these pests. Their favorite variety is Hubbard squash. Butternut squash, cucumbers and melons are less palatable but are sometimes affected. If the vines in your garden suddenly wilt, take a look at the base of the plant. Look for small holes in the vine, along with an accumulation of sawdustlike material. That’s frass, the debris larvae produce as they eat their way through the vine. As they eat, the larvae cut off water and nutrients, which kills the plant.

CONTROL — Because squash vine borer larvae are inside the vine, it’s difficult to get rid of them. But if you keep at it, you can minimize damage. In late spring, spray the vines weekly with an insecticidal soap to smother the eggs. Or spray the vine with Bt before the eggs hatch. This natural insecticide is safe to use on vegetables but needs to be eaten by the pest to be effective. In fall, destroy the vines as soon as possible after harvest to get rid of any remaining larvae. If you can till the soil to expose any cocoons to cold and predators, that will help, too.

Photo courtesy of Iowa State University

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Crown rot

IDENTIFICATION — Crown rot affects hosta, bleeding heart, phlox, daylily and many other perennials. Yellowing foliage and mushy stems appear just above the soil line. It can start any time during the growing season, but it’s most prevalent during hot, humid periods. Once called Southern blight, this fatal rot is now spreading into much of North America.

DAMAGE — Crown rot organisms live near the surface of the soil, waiting to enter a plant and destroy the tissue. It kills the plant if it’s not stopped, and can become a permanent problem in your garden.

CONTROL — Dig infected plants and remove the top 12 in. of soil. Bury everything in a hole several feet deep to keep the spores from spreading. Never add infected plants to your compost pile. One fungicide, Terrachlor^®, may save infected plants if it’s applied before the entire crown has rotted.

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Emerald ash borer
Agrilus planipennis Fairmaire

IDENTIFICATION — If you have an ash tree (Fraxinus spp.), keep an eye out for emerald ash borer. Native to Asia, this pest is a serious problem in Michigan, Indiana, Ohio and Ontario. Several surrounding states have infestations to a lesser degree.

Emerald ash borers (EAB) are slender with metallic green wing covers. But you don’t have to see the insects to know that they’re there. Adults chew small, 1/8-in.-diameter D-shaped exit holes in the tree in spring. Soon after they emerge, females start laying eggs in the crevices of ash tree bark. Larvae burrow back into the bark to overwinter, pupating into adulthood in early spring.

DAMAGE — Adults feed on leaves and don’t do a lot of damage. It’s the larvae, which feed under the bark, that cause problems. They disrupt the flow of water and nutrients, which eventually girdles and kills the tree. The tree can die within two years of initial symptoms. White, green and black ash trees are equally tasty to EABs. Dieback usually starts in the top third of the canopy and works downward.

CONTROL — New treatment methods provide hope that this pest can be beaten. The new pesticide Tree-age^® did very well in 2007, its first year of use. It’s applied every other year by trunk injection and can only be purchased and applied by certified arborists or landscapers. In Canada, a similar treatment, TreeAzin^®, is working, too. Predator wasps native to China have been released in Indiana, where results are still pending.

You can help prevent movement of EAB by not transporting firewood or logs from quarantined states to others. For more information check out www.emeraldashborer.info. If you suspect your tree has an infestation, contact your local extension agency to report it.

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American elder
Sambucus canadensis

IDENTIFICATION — A quick way to identify this tree seedling is to crush a stem or a few leaves and you’ll get a disagreeable odor. Break or cut a mature stem and you’ll discover a spongy white pith in the center. And last but not least, the creamy white flowers in spring and the dark purple fruits that follow are in large, flat-topped clusters.

FAVORITE CONDITIONS — Full sun to part shade in moist, fertile soil is where you’re likely to find American elder. It also tolerates moderately dry conditions.

CONTROL — Pull or dig out saplings or spray with a nonselective herbicide like Roundup^®.

PHOTO: © Joseph G. Strauch, Jr.

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Cedar-apple rust

IDENTIFICATION — In fall, you’ll spot hard brown galls on twigs of Eastern red cedar. In spring the galls swell, turn orange, as in the photo, and release spores.

DAMAGE — When those spores find the foliage of an apple tree in late spring, spots of orange rust, like the ones in the small photo, grow on the leaves during the summer. Infected leaves drop off in midsummer, leaving the tree unsightly. As they ripen, spores from the apple are then blown back to the cedar to continue the cycle next year.

CONTROL — Grow rust-resistant apple cultivars and don’t plant Eastern red cedars and apple trees in the same garden. If you have susceptible apple trees, spray them with a fungicide as a preventative when the flower buds begin to open in spring.

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Musk thistle
Curduus nutans

IDENTIFICATION — All the surfaces of the leaves and stems of musk thistle are covered with sharp prickles. The spiny multi-branched stems reach 2 to 6 ft. tall. From summer to fall, its showy red-purple flowers open, the flower heads drooping as they age.

FAVORITE CONDITIONS — The seeds of this biennial weed sprout in summer, in full sun or shade, in areas not regularly cultivated, such as fence rows, garden perimeters and lawns.

CONTROL — Sharp spines make hand-pulling this weed difficult. So hoe the young plants or spray a broadleaf herbicide before the seeds ripen.

PHOTO: © Jerry Pavia

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Chameleon plant
Houttuynia cordata

IDENTIFICATION — Often sold as an ornamental, the leaves of chameleon plant are green with margins of red, bronze or yellow and have a pungent odor when they’re crushed. The plant reaches 6 to 12 in. tall and spreads by underground rhizomes, rooting stems and seeds.

FAVORITE CONDITIONS — It prefers wet soil in sun or shade; in dry shade situations it spreads much slower.

CONTROL — Start digging and keep digging or spray with a nonselective herbicide. If you want to keep some, plant it in a buried container so the roots can’t run.

Click on the photo to see the damage

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Three-lined potato beetle
Lema trilinea

IDENTIFICATION — True to their name, these beetles have yellow bodies with three black stripes running down their length. Their heads are red-orange with thick black antennae.

DAMAGE — Larvae and adults chew ragged holes in the leaves of datura, nicotiana, tomato, potato and some other vegetables in midspring to midsummer.

CONTROL — Handpick adults in early spring if you can see them. As soon as you see damage in spring, mix up and spray tops and bottoms of leaves with Bacillus thuringiensis (Bt), a beneficial bacteria you can buy in granular or liquid form. Repeat spraying every week or so until midsummer. Dust plants with Sevin^® in early spring to kill the beetles. To avoid scorching plant leaves, don’t apply Sevin in liquid form during the hottest part of the day or if temperatures are above 85 degrees.

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Red clover
Trifolium pratense

IDENTIFICATION — Red clover is cultivated as a hay crop in agricultural areas, but is considered a weed elsewhere. It has fuzzy red-pink flowers and a V-shaped marking on each leaf. It can reach 20 in. tall.

FAVORITE CONDITIONS — You’ll most likely find red clover growing in sunny areas along garden edges and perennial borders, but rarely in tilled areas. It’s quite tolerant of wet soil conditions.

CONTROL — The stems of this weed root at nodes wherever they touch the soil. A broadleaf herbicide is the best control.

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Tobacco budworm
Heliothis virescens

IDENTIFICATION — Tobacco budworm larvae are generally yellow to yellow-green with a brown head, but body color can sometimes be pink, red or maroon, as well.

DAMAGE — Most larvae appear in August or early September and attack petunia, geranium, nicotiana, ageratum, mum, snapdragon, strawflower, rose and other flowers. They tunnel into or eat entire flower buds and petals and sometimes leaf buds, too.

CONTROL — Handpick from plants around dusk when caterpillars are least active. Buy beneficial insects, such as stink bugs, green lacewing larvae and lady beetles from garden centers or mail-order sources, such as Gardens Alive. Release them on calm days in late spring, in early morning or early evening. Mix up pyrethroid insecticides and spray plants until leaves are dripping. These chemicals attack all stages of the insect, as well as the eggs, so you may only need to make a couple of applications.

Photo courtesy Chris Wilson, Hallson Gardens

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Hosta Virus X

IDENTIFICATION — Unusual hosta leaves, like the one in the photo, could be symptoms of hosta virus X (HVX), a disease that’s spread rapidly in recent years.

DAMAGE — Though the virus doesn’t kill plants, the pigment and texture of the leaves may be distorted. (Markings can be mottled or have an “ink-bleed” look.) The biggest threat is how quickly the virus spreads to other hosta plants.

CONTROL — Healthy plants are infected when their sap comes in contact with the sap of an infected plant. So sterilize pruners or spades with a 10-percent bleach solution between plants as a precaution. To avoid rusty tools, dry them off afterward. There’s no cure for HVX so destroy infected hostas. For more information, go to www.hostalibrary.org

PHOTO: © Mary Jane Hayes

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Eastern tent caterpillar

IDENTIFICATION — There are several kinds of caterpillars that spin webs in trees, but you’ll see Eastern tent caterpillars and their webs in late spring or early summer. They’re black, with irregular blue and white markings and a solid white stripe down the back. Adult moths are about 1 in. long and red-brown with two white stripes on the front wings.

DAMAGE — Usually, the worst thing about these caterpillars is that their webs look messy, but the pests can defoliate and stress small trees. You’ll see webs in the forks of twigs or branches of trees east of the Rocky Mountains. Webs usually don’t enclose leaves, as the caterpillars leave the webs to feed. They generally feed in the morning or evening, when it’s cool, but may also feed during the day. If it’s raining or hot, they often retreat to the web.

CONTROL — You can pull down the webs, pests and all, and destroy them. Check the web first to be sure the caterpillars are “at home.” Wear gloves, because the hairs on the caterpillars can irritate some people’s skin. A strong jet of water can help knock down webs that are too high to reach.

Bt (Bacillus thuringiensis) is a common control, but it has to penetrate the webs to be effective. And you may need a professional to spray a large tree.

Click on the photo for a larger image

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Columbine sawfly
Pristophora aquiligae

IDENTIFICATION — These larvae of a non-stinging wasp have green heads and bodies without stripes or spots. You’ll often see them on the tops or undersides of columbine leaves in late spring.

DAMAGE — Larvae strip leaves by chewing along the edges toward the inner leaf, eating all but the midveins. Their green color blends in well with the leaves, so you may not notice them until they’ve done a lot of damage.

CONTROL — Many birds eat sawflies, so grow bird-attractors like berry and seedhead plants in your garden. Handpick, or spray insecticidal soap on the tops and bottoms of leaves every few days while you see the caterpillars. If most of the leaves are gone, cut the plant down to the ground and it’ll produce fresh foliage in a few weeks or come back the next year ready to bloom.

If you want, spray spinosad, an insecticide made from bacteria, on the leaves before or after you see the larvae (it works both when the caterpillars eat it or come in contact with it).