Click to see a foliage detail.

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Pennsylvania pellitory
Parietaria pensylvanica

IDENTIFICATION — Growing 6 to 18 in. tall, Pennsylvania pellitory has leaves with slightly fuzzy undersides. Click the image to see a foliage detail. At first glance, this spring weed’s narrow upright form looks broader because the plant often grows in dense colonies. The green flowers along the main stems have no petals and are barely noticeable.

FAVORITE CONDITIONS — Although it prefers part shade, you’ll find Pennsylvania pellitory in full sun if the soil never dries out. It reseeds rampantly, especially in areas that are tilled annually.

CONTROL — The shallow, fibrous roots are easy to pull or hoe out. (Check out our favorite hand hoe.) If you miss pulling a few weeds, red admiral butterfly caterpillars will enjoy eating the leaves. But herbicides are effective if you need to eradicate large stands of this annual.

Read about more spring weeds in the April issue of Garden Gate magazine. On newsstands now!

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Eastern cottontail
Sylvilagus spp.

IDENTIFICATION — Most of us know a rabbit when we see it — long ears, fuzzy tail and a piece of your favorite plant dangling from its mouth! Eastern cottontails, the most common, are found across North America.

DAMAGE — These pests do eat annuals and perennials, but the damage is usually cosmetic, although they can ruin a vegetable garden or your favorite spring bulbs. But worse yet, they can girdle and kill shrubs and small trees, often the most expensive plants in a garden. Damage to trees is more severe during the winter when there aren’t green plants for rabbits to munch. If you look closely at the trunk, you’ll see characteristic small, paired tooth marks. The damage usually starts a couple of inches from the ground and goes above the highest snow line.

CONTROL — First, make the area less attractive by removing hiding places like brush piles. There are hundreds of home recipes for keeping rabbits away. Some people swear by them; others may find that they simply don’t work. In any case, they probably won’t keep really hungry rabbits at bay for long.

Chemical repellents, like Ro-Pel^®, are effective, but most of them need to be reapplied after rain and several times during the winter. A cylinder of 1/4-in. hardware cloth will keep rabbits away from shrubs and young trees. The bottom of the cylinder needs to be 3 in. below the soil’s surface to prevent digging, and the top needs to be 24 in. above the anticipated snow line. Or you can use rigid plastic tree guards, although in extreme cases, rabbits can chew through them.

You can fence off an entire bed with chicken wire or hardware cloth, but make sure there are no rabbits hiding inside when you’re fencing. Check the bed periodically during the winter to make sure that no rabbits have managed to move in.

Click for a foliage detail.

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Box elder
Acer negundo

IDENTIFICATION — Box elder leaves have three lobed leaflets that are somewhat pointed. The stems are smooth green to dark red with a white waxy coating that you can rub off with your fingers. Click to see a foliage detail.

A single or multi-stemmed tree that grows up to 75-ft.-tall, box elder is not good to have in your garden. Winged seeds can sprout almost anywhere and new trees can also sprout from the shallow roots, which make it hard to grow anything nearby. In addition, its weak wood breaks easily in storms.

FAVORITE CONDITIONS — Box elder is not picky. Any place in full sun to part shade with moist, even wet soil is fine. It readily adapts to almost any conditions except deep shade or very dry soil.

CONTROL — Pull seedlings if you spot them when they’re young enough. This is the best method in areas where you can’t dig or spray, such as in ground cover beds.

Spray young sprouts in open, mulched areas with nonselective herbicides, such as Roundup^® Poison Ivy & Tough Brush Killer Plus. Always follow the label directions, but you usually apply these products to actively growing weeds in spring or summer.

Digging is the preferred method in beds where spraying a herbicide would be risky for the other plants. Plus, unlike spraying actively growing weeds, digging lets you get rid of box elder any time you can push the shovel into the soil.

Once box elder gets too big to dig, you’ll need to use a saw to remove it. Then dribble or brush on a systemic stump killer around the edges where the sap is flowing. It’s absorbed into the wood and kills the roots.

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Crown vetch
Coronilla varia

IDENTIFICATION — Crown vetch grows up to 2 ft. tall. It has a dense, sprawling habit with stems that can be 5 to 6 ft. long. Pink flowers are followed by 3-in.-long seed pods. Although it’s still being sold and planted, you do not want this near your garden. It can spread quickly with seeds, root and stem pieces, and it’s tough to get rid of.

FAVORITE CONDITIONS — You’ll find this pest in full sun to part shade in rocky or rich soil. Once used to control erosion along roadways, this weed escaped and is forcing out native plants.

CONTROL — Dig crown vetch out of established gardens or use a selective herbicide in turf areas. It’s a perennial, so for the best control, apply herbicide in fall, before the leaves go dormant, and again in spring as the leaves emerge. Repeated mowing also keeps this weeds from producing seeds.

When you’re tackling crown vetch and other weeds with tough roots, a good weeding tool, such as our Soil Knife, really comes in handy.

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Four-lined plant bug
Poecilocapsus lineatus

IDENTIFICATION — The four-lined plant bug is one of the most common pests in the garden. It likes to feed on more than 250 species of ornamental, woody and edible plants. In urban areas the four-lined plant bug is usually found on perennials and shrubs.

Damage from this pest starts in late spring when plant foliage has emerged and eggs hatch. Nymphs look like tiny adults but are bright red to orange with black wing pads. Over a period of about six weeks and several molts, the four-lined plant bug gradually changes color. Adults are yellow to chartreuse with, you guessed it, four black lines running down the wing covers on their backs. Since mature bugs have wings, they move from plant to plant, feeding for about a month until they mate. After mating, the female cuts a small slit in a plant stem to make a winter home for her cluster of eggs. By midsummer most of the adults have died. There’s just one generation of four-lined plant bugs each year.

DAMAGE — You’ll know four-lined plant bugs are around if you see tiny round sunken spots that are brown to translucent on the foliage of your plants. With heavy damage, the leaves might be distorted or curled.

Damage is often mistaken for leaf spot disease. But foliar disease spots from fungi or bacteria are irregular, and the marks left by the four-lined plant bugs are almost uniform in shape and size.

CONTROL — What can you do to get rid of this hungry insect? Start checking your garden in spring for damage. Since the nymphs can’t fly, their damage tends to be clustered in one area. And it’s easier to get rid of them while they’re less mobile. But whether you have nymphs or adults, the most environmentally friendly way to remove these unwelcome pests is with a few sprays of insecticidal soap.

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Groundhogs
Marmota monax

IDENTIFICATION — Punxsutawney Phil may be cute, but a wild groundhog in your garden can be a problem. Though dandelion greens, clover and grasses are some of their favorites, garden vegetables and fruits often disappear when these furry pests are around. Their enthusiastic burrowing can cause nearby plants to suffer, too.

Sometimes called woodchucks, groundhogs are 16 to 27 in. long with dark red-brown hair, short, bushy tails and sharp teeth. Widely distributed in North America, groundhogs are particularly common in the eastern United States up into northern Quebec and Ontario. In the West, they are found in Alaska and southern Yukon and Northwest Territories.

LIFE CYCLE — Groundhogs can live up to 10 years However, the average life span in the wild is probably less since they are on the menu for such predators as coyotes, owls and hawks.

Each spring, females give birth to a litter of four to six helpless kits. They grow quickly and spend all summer binging on greens to put on weight for winter hibernation. Around October they retire to their dens and sleep until spring.

But how do they know when to wake up? The groundhog’s internal clock is affected by annual changes in daylight.

CONTROL — To keep groundhogs from settling in your garden, clear areas with tall grass and remove brush piles, where they like to hide. Groundhogs are timid and can be frightened away by changes in their environment. If you already have groundhogs, try a repellent, such as Messina Wildlife Management’s Groundhog Repellent. It smells and tastes bad to the groundhog.

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Stinging nettle
Urtica dioica

IDENTIFICATION — If you’ve ever walked along a wooded path, you’ve probably encountered stinging nettle. This perennial weed, with bright- to dark-green leaves, can grow to 3 to 6 ft. high. The square stems are covered with fine hairs, which break and release a sap when you brush against the plant. If the sap gets on your skin, it causes a stinging feeling that lasts for a few minutes or longer, depending on how sensitive you are. From May to October, pale green flowers open along the stem between the leaves.

FAVORITE CONDITIONS — You’ll find stinging nettle in damp, fertile, shady locations. In the wild, it grows well along stream banks and at the edge of wooded areas. But it’ll also tolerate more sunny spots, such as an open field or roadside. In the garden, stinging nettle may pop up on bare soil, too.

CONTROL — Stinging nettle spreads by seed and by rhizomes, which allow it to colonize an area quickly. To control small patches or individual plants, pull them by hand, but be sure to wear gloves and long sleeves so you don’t get “stung.” If you’re dealing with a large colony of plants, try mowing them off and using a garden fork to remove the roots. Herbicides, such as glyphosate or 2,4-D, are also effective and spraying them keeps you from coming in contact with the plant.

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Cyclamen mite
Phytonemus pallidus

IDENTIFICATION — These minute, semitransparent mites are too small for the naked eye to see. They hide in young, tender stem ends, leaves and flower buds of cyclamens (Cyclamen spp.) and many other indoor and outdoor plants. But their damage is obvious. Like all sucking bugs, these spider relatives cause wrinkled, curled growth and stunted flowers and foliage. Their damage first appears as light, speckled areas, which later spread over the entire leaf surface. Affected foliage turns yellow and even­tually dies and drops off.

CONTROL — Cyclamen mites crawl from plant to plant across “bridges” where leaves touch each other or they hitch a ride on clothing or hands. Examine plants you bring into the garden or the house for signs of the pest, and wash hands and clothing after working with infested plants.

If you catch them early, you can remove cyclamen mites from plants with a high-pressure stream of water. Spray the entire plant, especially the undersides of the leaves, with a jet from a hose. Or, use an insecticidal soap, such as Safer^®, on all the leaf surfaces. Spray until the soap drips off. Just discard heavily infested plants in the trash.

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Common buckthorn
Rhamnus cathartica

IDENTIFICATION — Growing quickly to a large shrub or small tree up to 20 ft. tall, common buckthorn has sharp spines at the tips of the twigs that can be dangerous as you walk through brushy areas. If you scratch the bark of this woody weed and it’s yellow underneath, you’ve found common buckthorn. Late in fall you’ll also notice that the foliage stays on this pest long after other leaves have fallen. And look closely at the leaves — there are usually three to five pairs of veins in each one.

FAVORITE CONDITIONS — Common buckthorn prefers places in part shade in moist to dry soil.

HOW IT SPREADS — Birds eat and spread the seeds of the 1/4-in.-diameter messy black fruit in fall.

CONTROL — When the plant is a seedling, pull or dig it out of the ground. If it’s too large for this, spray the plant with a nonselective herbicide, such as Roundup^® Poison Ivy & Tough Brush Killer Plus in spring or late summer. Or cut down the tree and dribble or brush on a systemic stump killer around the edges where the sap is flowing. It’s absorbed into the wood and kills the roots. Be careful, it can kill any plant it gets on.

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Gooseneck loosestrife
Lysimachia clethroides

IDENTIFICATION — It may produce attractive arched white flowers in late spring to summer, but this aggressive 3-ft.-tall plant can take over your garden quickly.

FAVORITE CONDITIONS — Gooseneck loosestrife prefers part shade and moist soil. Dry soil and full sun scorch the foliage and slow down the plant’s growth. It’s cold-hardy in USDA zones 4 to 9 and heat-tolerant in AHS zones 9 to 1.

CONTROL — If you want to grow it, contain the roots in a buried plastic pot. The roots can be hard to pull, so digging any time of year is best. You can also use nonselective herbicides.

A BETTER ALTERNATIVE —Nothing else will have those distinctive arching goose necks, but bluestar will have a similar size and texture. Between 2 to 3 ft. tall with an equal spread, it’ll bloom best in full sun to part shade. The clusters of pale-blue flowers open in late spring. Bluestar (Amsonia tabernaemontana) is cold-hardy in USDA zones 3 to 9 and heat-tolerant in AHS zones 9 to 1.

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Winter burn

IDENTIFICATION — The leaves of your broadleaf evergreens look green now, but the leaf edges of broadleaf evergreens, such as boxwoods (Buxus spp.), turn bronze in winter.

DAMAGE — Plants can experience winter burn, even in milder climates, as they contend with cold, dry air and wind. That wind can suck the moisture right out of leaves. And if water isn’t plentiful or the ground is frozen, the roots can’t take up any additional moisture. In a worst-case scenario, the branch can dry out completely and die.

CONTROL — Prevent winter burn by watering your plant well during dry spells through­out the growing season, as well as during warm spells in winter. Mulch to keep soil moist in summer and prevent rapid soil temperature changes. Also, apply an antidesiccant spray, such as Wilt-Pruf^®, in late fall and again in late winter. Products like this help reduce water evaporation from leaves.

Click to see a larger image.

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Mineral deposits

IDENTIFICATION — Along with soil and light, water is one of those essential things that you need to grow plants. Ever notice the crusty formations that “grow” in your house plants’ soil? These are mineral deposits left from watering. They are often accompanied by yellowed leaves and browning leaf margins.

CONTROL — First, check the pot’s drainage. Make certain that water drains freely from the pot so any minerals that are in the water are flushed away. If the water drains slowly or not at all, your plant needs better drainage. If the pot drains well, try chan­ging to a lightweight soil mix. Filtering your water before giving it to your plants will remove many of the minerals before they get to your plant. A countertop water filtering system, such as a Brita^®, will work for this.

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Common mullein
Verbascum thapsus

IDENTIFICATION — At first glance, this weed could be a tall, striking ornamental for the back of your border. But its soft gray foliage and tall spikes of yellow flowers can be deceiving. It could take over your garden. Just one common mullein plant is capable of producing about 180,000 seeds, which can remain viable in the soil for 100 years or more.

Common mullein, also known as woolly or flannel mullein, is a biennial. The first year it’s a low rosette of gray feltlike leaves that can be more than a foot long. In its second year of growth, cylindrical spikes of small cup-shaped yellow flowers appear. The flower stalk can be up to 8 ft. tall and often blooms from June until early October. Both the leaves and the stem are covered in soft woolly hairs. Spent flower stalks remain standing through the winter.?

FAVORITE CONDITIONS — Found throughout much of North America, common mullein prefers lean, dry sandy soils. But it will adapt and grow just fine in richer soils, too. And like many plants with gray woolly foliage, common mullein needs plenty of sun to reach its full size. Some of its favorite spots are gravelly areas like ditches, railroad embankments or along driveways. Occasionally you’ll find it growing in vacant lots, fence rows or old garden areas that are rarely cultivated.

CONTROL — You can easily pull common mullein plants out by hand, especially in loose or gravelly soil, because they usually have a single taproot. But if you can’t pull a mature plant, make sure to remove any blooms and seed capsules before they spread. To prevent any unwanted seedlings, dispose of the removed stalks in plastic bags that you send away in the trash.

Herbicides are especially effective on young plants. Apply glyphosate, a nonselective herbicide, to the foliage while the plant is actively growing in spring.

Click to see a larger image.

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Clematis wilt

IDENTIFICATION — Even if you grow clematis that are very resistant to wilt, next summer your plant may still get it. This common clematis disease is caused by a soil-borne fungus. ?

DAMAGE — Wilt affects the plant almost overnight. It attacks the tip growth and youngest foliage first, and then the stem or the entire plant quickly turns black. ?

CONTROL — Cut the affected growth back, remove all the plant debris and drench the soil once a month for several months with a copper-based fungicide. Wilt won’t kill your clematis; the plant will sprout again from leaf nodes below the soil.

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Cytospora canker

IDENTIFICATION — If your Colorado spruce (Picea pungens) has dead branches, Cytospora canker could be to blame. Yellowing needles is the first noticeable symptom. The discolored needles show up in spring or early summer, change to purple, then turn brown and fall off in winter. The process is repeated each season until an entire branch is dead. A closer look shows a clear, sticky resin oozing from the affected branch. Over time, the resin accumulates to form a ridge surrounding the canker, or dead tissue, and dries blue-white. Any branch on the tree can become infected, but the lower ones tend to be first. Cytospora canker won’t usually kill the tree, but it does disfigure it.

DAMAGE — This disease is caused by a fungus called Cytospora kunzei (or Leucostoma kunzei), which enters through wounds. The fungus is spread by wind, rain, insects, birds and mammals. Cankers generally start at the base of a branch and grow around it until the branch is girdled and dies. It can take several years or even decades to girdle a large limb or the trunk.

Colorado spruce living east of the Rocky Mountains are most often affected. Spruces 10 to 15 years old and those stressed by environmental factors, such as drought, are most susceptible. Norway spruce, Douglas fir and other evergreens can also become infected, although less often.

CONTROL — There’s no cure for Cytospora canker, but there are some preventative
measures you can take. First of all, avoid environmental stresses by planting your spruce in moist, well-drained soil and giving it plenty of space to grow. Deep watering during dry periods and annual fertilizing will keep your tree healthy. Also, avoid injuries to the bark so the fungus won’t have an entry point.

If you notice infection, remove the affected branch close to the trunk during dry weather so rain doesn’t carry spores into the wound. Clean your pruning shears or saw in a 10-percent bleach solution between cuts.

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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.