Carpenter ants are often mistaken for termites. The reproductive forms of both insects are winged. However, there are three major differences between them.

Carpenter ants have a narrow waist (like a wasp) and three distinct body parts–head, abdomen and thorax. Termites have a straight body without a waist.

Termites and carpenter ants both have four wings. The back wings of a carpenter ant are shorter than the front pair, but termite wings are all the same size. Carpenter ant wings have few veins and are typically clear; termite wings are somewhat milky with many veins. (Read more…)

Walking recently through softly falling leaves, I started thinking about what a phenomenal process leaf drop is. Like most happenings in nature, there is an important reason why leaves fall. It’s not just so we can complain about raking them.

Plants need a coping mechanism for winter or they perish. Trees, like perennial plants, have to survive the freezing temperatures and harsh winds of winter. Some parts of trees, such as stems, twigs, and buds, are able to survive extreme cold. The tender leaf tissues of broad-leafed trees would freeze in winter, so these trees must shed their leaves. Evergreen trees, however, have needles that are covered with a protective, wax-like coating, and fluids inside their cells contain substances that resist freezing. (Read more…)

There’s something special about fall decorations in the Midwest. The pumpkins, corn stalks, Indian corn and other decorative materials seem to blend so naturally and wonderfully into the fall landscape and its colorful palette of changing foliage.

Another plant frequently used in fall decorations is bittersweet. The orange and scarlet berries of this vine are excellent for fall displays and wreaths. In addition to its colorful berries, bittersweet also produces nice yellow foliage in the fall. (Read more…)

Burning bushes (Euonymus alata) consistently produce some of our most vibrant fall foliage. Their glowing red leaves are definitely a show stopper in the landscape. Another benefit of these shrubs is that they are very easy to grow in Central Illinois, which accounts for why they are frequently planted along interstate highways, where conditions are less than optimal for most ornamental plants. These shrubs are sometimes referred to as winged euonymus because of the corky “wings” which flare out from their branches.

Native to northeastern China, Korea and Japan, this shrub is a member of the bittersweet family. It is believed the burning bush was introduced into the United States about 1860. By 1900, it was being cultivated in most American nurseries. Because most varieties are flat-topped, wide-spreading and tolerate pruning well, they have often been used for hedges, but they also work well as specimen or foundation shrubs. Cultivar heights vary from a compact three feet up to 20 feet. (Read more…)

In the fall when walnuts are harvested, I am always reminded of the fact that black walnuts produce a toxic substance known as juglone, which can be fatal to some plants. Sensitive plants can be injured or killed within a couple of months when they come in contact with the root zone of black walnut trees. Humans can also have allergic symptoms when walnut trees shed their pollen, typically in May.

The toxic zone produced by roots around a mature black walnut tree occurs on average in a 50- to 60-foot ra-dius from the trunk, but can expand as far as 80 feet. As trees grow each year, the toxic zone increases. It is im-portant to know that even small trees can have a root system twice their height.

Plants injured by juglone toxicity will exhibit symptoms such as foliar yellowing, wilting and eventual death. The largest concentration of juglone occurs in black walnut buds, nut hulls and roots. It is also present in smaller quantities in their leaves and stems. Juglone is not very soluble in water and, therefore, does not move very far in soil. The greatest quantity of the toxin is generally found in the area immediately under the canopy of the black walnut tree due to greater root density and the accumulation of juglone from decaying leaves and nut hulls. (Read more…)

A couple of weeks ago, I found several patches of moss growing in my garden. This would have been a common occurrence in Seattle, my previous home, but it seemed rather unusual for Central Illinois in September, and I attribute it to our cool, wet spring and summer.

Moss has a unique beauty and has become the focus of a new form of gardening. Since it generally loves acidic, compacted, deeply shaded and poorly drained sites, moss is wonderful for locations that would otherwise be a gardening nightmare.

To start a moss garden, you can simply nurture what nature is already providing or you can purchase sheets or plugs of moss to transplant. Be forewarned that moss can be expensive. Four types of moss are typically used in moss gardens: fern (or sheet) moss, the most economical, versatile and fastest-spreading groundcover; rockcap, used for walls, boulders, and pond edging; haircap, which prefers partial sun and well-drained soil; and cushion, which prefers sandy soil, tolerates partial sun and is excellent for rock gardens. (Read more…)

Japanese maples are prized for their graceful form and lacy, delicate foliage, but many also provide stunning color in the fall. There are several Japanese maple varieties. The most common are the Palmatum and Japonicum types.

Palmatums have leaf lobes that are softly, moderately or deeply divided. Dissectum Japanese maples in the Palmatum group are typically called lace leaf or cut leaf types. Their leaf lobes are heavily divided and dissected into sublobes, and they usually have a weeping form. The Japonicum type is commonly named the Full Moon Japanese maple. Many cultivars have variegated leaves.

Like their leaf shape, Japanese maples are fragile. Planting them in the right location is critical for their survival. They do best in morning sun and afternoon shade, especially when young. An eastern exposure is ideal. Full sun should be avoided. Some sun, however, is required to achieve optimal leaf coloration. Variegated types require more shade, while green varieties tolerate more sun. Japanese maples need a period of cold dormancy and do not perform as well in warmer climates, but protection from harsh winds and late spring frosts is necessary.

Good drainage is another major requirement for growing healthy Japanese maples. The crown, where the roots and the trunk meet, should never be below soil grade. Newly transplanted trees should be regularly watered during their first year. Because Japanese maples have shallow root systems, they should be covered with a 2- to 3-inch layer of mulch to retain soil moisture and provide protection during freeze/thaw cycles. Keep the mulch 4 to 6 inches away from the trunk to avoid crown rot and insect damage.
Some varieties of Japanese maples are small enough to be grown in containers or as bonsai. However, dwarf types often have an equal horizontal spread and need to be spaced accordingly.

Many horticulturists recommend planting Japanese maples only in the spring. They feel this gives the plant more time to develop a good root system and eliminates the chance of fall growth being heavily damaged when cold weather arrives. A low-nitrogen fertilizer can be applied sparingly in early to mid-spring.

To achieve the best fall color, reduce the amount of water you give your Japanese maple in late summer and early autumn, but do not let it dry out completely. This will encourage it to stop producing green leaves and begin its wonderful foliage color change.

Smith is a University of Illinois Extension Master Gardener in McLean County. For horticulture questions or information about the Master Gardener program, call (309) 663-8306 or visit www.mcleanextension.org.

A major topic of discussion recently has been the swarming insects in our area, and it appears other Midwestern cities have similar activity. Most of these appear to be various types of aphids.

One of the problem insects has been described as being tiny, dark and winged. These are probably soybean aphids. In late summer and early fall, they migrate from soybeans to buckthorn trees to lay their eggs. While they don’t technically bite, they do sometimes probe your skin to see if you are a plant that would be edible. Avoid wearing orange and yellow fabrics, which seem to attract them. No controls are recommended or practical.

Other swarming insects have been described as dandelion fluff floating in the air. They could be one of several types of woolly aphids. Common types include woolly apple aphid and woolly alder aphid. They are usually minor pests and rarely cause severe damage to trees.

Woolly apple aphids are found on members of the rose family, such as crabapple, cotoneaster, hawthorn, mountain ash and pyracantha. Stems and leaves of these plants often appear white and cottony on the undersides. Aphids suck sap from their host and produce a sticky substance called honeydew. Cicada killers, yellow jackets, bumblebees and other bees and wasps are attracted to the honeydew they produce. Woolly apple aphids also feed on host plant roots. In the fall, they move to American elm trees where they mate and deposit eggs. In late spring, the aphids return to a rose family plant.

Woolly alder aphid hosts are alder and silver maple trees. Their eggs are deposited on silver maples in the fall. When the eggs hatch in the spring, the nymphs can be found on the undersides of newly opened silver maple leaves. In late July, the winged woolly alder aphids move to alder trees. In the fall, they return to silver maples to begin the reproductive cycle again. Clues that this insect is present include leaves that curl inward, white fuzzy masses on leaf undersides and along stems, and evidence of honeydew.

Woolly aphids also infest single host plants like beech, birch, Douglas fir, hackberry, hemlock, pine and spruce. Insecticidal soap sprays can help natural enemies keep woolly aphid colonies in check. Imidacloprid can be used for heavy infestations. Acephate (Orthene) is also effective.

Aphids will remain active, but not in current swarm levels, until a hard frost.

Smith is a University of Illinois Extension Master Gardener in McLean County. For horticulture questions or information about the Master Gardener program, call (309) 663-8306 or visit www.mcleanextension.org.

Keep watch on your star and saucer magnolia shrubs for magnolia scale, one of the largest and most visible scale insects found in the Midwestern states. Besides magnolias, these scales may also feed upon Daphne, Virginia creeper and tulip trees.

Magnolia scales have been very active in Northern Illinois this year, but have also been identified in Peoria. (Read more…)

Horticulture is often an inexact science. It has elements of television shows like “House” and “CSI.” Sometimes we never reach a conclusive answer to plant problems — and that can be frustrating. A current problem with boxwoods is a prime example.

Many boxwoods in the area are exhibiting random browning of sections throughout the plant. No specific cause of this discoloration and dieback has been positively identified, although several causes are possible. (Read more…)

Viburnum leaf beetles (Pyrrhalta viburni) were found in Cook County in July. This was the first documented sighting of this insect in Illinois, although it has been a pest in Ohio, Pennsylvania, New York, Maine and Massachusetts for several years.

These insects have a preference for European cranberrybush, arrowwood and American cranberrybush viburnums. They will also feed on wayfaringtree, rafinesque, blackhaw, mapleleaf, nannyberry, and Sargent viburnums. Korean spice, Burkwood, doublefile, Judd, lanatanaphyllum and leatherleaf viburnums appear resistant. Viburnum varieties that have little hair on their foliage seem to be preferred.

Native to Europe, viburnum leaf beetles are particularly troublesome because both the adult and larval stages feed on viburnum leaves, defoliating them between the midrib and larger veins. When severe defoliation occurs, the damage can cause dieback and can potentially kill shrubs. Currently, this is the only insect known to cause such damage on viburnums.

Adult viburnum leaf beetles are one-quarter to three-eighths of an inch long. Females tend to be larger than the males. They are yellowish to light brown in color and have a sheen in sunlight. The adult leaf beetles eat through leaves, creating irregular, circular holes. In late summer and fall, the females lay their eggs in holes they have chewed in the bark of viburnum twigs — typically current year growth. After their eggs are deposited, they cover them with excrement and fragments of chewed bark. The egg deposit sites are often arranged in straight rows on the under-surface of twigs. The females can lay up to 500 eggs.

After overwintering on the twigs, the eggs hatch in May of the following year. Larvae, usually in groups, then begin feeding on and skeletonizing viburnum leaves. They are typically found on the underside of tender, newly expanded foliage. The mature larvae are larger than the adults (about one-half-inch long), are greenish-yellow to white in color, and are covered with dark spots. In early to mid-June, the larvae drop to the ground, enter the soil, and pupate. Adults typically emerge in mid- to late July and will remain active until the first frost.

At present, the most effective control method for these pests is to prune out and destroy infested twigs. Pruning should be done from October until April, after the eggs have been laid and before they hatch in the spring. If desired, imidacloprid, carbaryl or acephate are suggested chemical controls.

Smith is a University of Illinois Extension Master Gardener in McLean County. For horticulture questions or information about the Master Gardener program, call (309) 663-8306 or visit www.mcleanextension.org.

The mid-Atlantic and eastern states have experienced an outbreak of late blight this year. This blight —Phytophthora infestans — is the disease that caused the devastating Irish potato famine. Late blight has not been a serious problem in Illinois because the disease does not overwinter here.

However, the disease can be spread from other states. Our cool and wet weather this year has been ideal for its development. The UI Plant Clinic recently confirmed that a tomato in northern Illinois was infected with late blight. (Read more…)

Are small branches and twigs dropping from some of your trees? This may be the handiwork of either the twig girdler or twig pruner. Both insects attack a wide range of trees, including elm, hackberry, honeylocust, linden, oak, poplar, redbud, sassafras and sweet gum. Branches up to 3 feet long may drop from a tree due to damage from these insects. There are similarities between the insects, but girdler adults sever a twig from the outside, while the pruner larvae sever the twig from the inside.

In the fall, adult twig girdler females chew circular notches around a twig, in effect girdling it. The females lay eggs underneath the bark in a hole they have created in terminal and lateral twigs or branches. Leaves eventually turn brown after the female lays eggs and feeds. The eggs are placed beyond the girdled area, and the girdled twigs soon die, break off the tree, and fall to the ground. The eggs hatch into larvae and overwinter inside the twigs on the ground. Twig girdler larvae tunnel toward the severed end and feed on woody tissue. In spring and summer, the larvae move into a pupal stage. During late summer and fall, after their development is complete, the adult twig girdler beetle emerges. Females live about 6 to 10 weeks, but can lay between 50 and 200 eggs during this period.

Adult twig pruner females chew a small hole in the bark of a twig and deposit their eggs near where a leaf attaches to a stem. The eggs hatch into larvae covered with long, lemon yellow hairs. Larvae enter trees and feed within the center of a small branch or twig, creating a tunnel toward the base. They then migrate to the sapwood, making concentric circular cuts. Eventually the larvae migrate back into the center tunnel and plug it with frass, a sawdust-like substance made from plant material and insect waste. Wind causes the branches or twigs to break and drop to the ground. Larvae in the severed branches and twigs continue to feed and overwinter in the pupal stage. In the spring, the adults emerge from the branches and twigs to repeat the cycle.

Controlling both insects primarily involves removing and destroying the fallen twigs and branches. Use of insecticides is not recommended because it is very difficult to control the larvae since they are inside the twigs and branches.

Linda Smith is a University of Illinois Extension Master Gardener in McLean County. For horticulture questions or information about the Master Gardener program, call (309) 663-8306 or visit www.mcleanextension.org.

Diagnosing tree problems can be difficult. Symptoms in the tree canopy or on the trunk can sometimes be indications there are problems below the soil surface.

Tree root systems consist of perennial roots and short-lived feeder roots. Large, woody tree roots are generally in the top 6 to 24 inches of the soil and do not grow deeper than 3 to 7 feet. These roots are critical because they anchor the tree, conduct water and minerals through the tree, and store food and water. (Read more…)

A few weeks ago, I was thinking about my maternal grandmother, so I headed out to my stand of hollyhocks and made a hollyhock doll.

That certainly brought back a flood of memories. It was wonderful to know too that my hollyhocks are descendants from seeds given to my mother well over 50 years ago.

Hollyhocks have a long history in U.S. gardens. They were introduced from England in 1631 and soon became so numerous they were called alley orchids.

While amid my hollyhocks, I noticed they had leafminer damage. Leafminer larvae cause damage to plant leaves by tunneling between the upper and lower leaf surfaces to feed on the inner part of the leaf.

This results in white, light green or brown serpentine trails on the leaves. Besides hollyhocks, various types of leafminers damage chrysanthemum, columbine, delphinium, larkspur, nasturtium, and verbena.

Vegetables can be affected too. These include lima and snap beans, beets, cabbage, chard, lettuce, peppers, radishes, spinach and turnips.

Leafminer damage is not fatal to hollyhocks, but it does inflict aesthetic damage. If trails are detected, pick off and destroy infested leaves. Do not compost the infested plant material.

Larvae are generally present in late June and early July. They can be repelled by spraying the plant with an insecticidal soap.

Leafminers overwinter in the soil and emerge in early spring. You can reduce the chance of a recurring problem by performing a thorough fall cleanup.

Remove weeds in the area and cultivate the soil to expose the insects to birds and other predators. Apply a winter mulch only after the ground has frozen.

Hollyhock sawfly is also a pest of hollyhocks. Larval feeding is typically seen in middle to late summer and can often be confused with Japanese beetle activity. Hollyhock sawfly larvae are pale green with black-colored heads.

Tiny black-colored spines are present on each body segment. The larvae are skeletonizers that feed on the lower surface of the leaf, leaving behind only the upper surface and main leaf veins. They often feed in groups.

Sevin is an effective control, but must be applied as soon as the larvae are discovered. Mature larvae spin a web over themselves, usually near the plant base, and pupate. The adults are black and fly-like. They are distinctive because their antennae are split almost to the base, making it appear as though they have four antennae.

Smith is a University of Illinois Extension Master Gardener in McLean County. For horticulture questions or information about the Master Gardener program, call (309) 663-8306 or visit www.mcleanextension.org.