Category: Pest Management

Bagworms have already left their mark this year on evergreens such as junipers, arborvitae, and chamaecyparis. You can act now, though, to reduce their population for next year. Bagworms overwinter as eggs inside the leaf covered bags left hanging on the tree. Remove the bags before spring and destroy them by squashing them underfoot. Handpicking usually provides sufficient control. In June the tiny caterpillars will hatch, and if they appear in large numbers, you can spray them with a pesticide containing Bacillus thuringiensis (Bt).

Give your houseplants an April shower in December. Dust that collects on the foliage blocks out needed sunlight and can clog the pours of the leaf surface, affecting the plant’s ability to breathe. Rinsing your plants gently with tepid water will also wash away mites and other pest insects that may be on the plant.

Deciduous shrubs may need protection from deer, rabbits, mice, and other animals that eat the buds, bark, and twigs of many plants. Your local nursery or home center may carry animal repellents or you can use tree wraps, hardware cloth, and shrub rings. Try using shrubs that these animals do not normally eat, including mountain laurel, Japanese plum yew, and holly.

Be resourceful and creative with your holiday decorations by using small branches you’ve pruned from your boxwoods. Boxwoods are susceptible to Volutella blight, a fungus that thrives in damp conditions. Thinning opens the branching structure of the plant, improves air circulation, and creates unfavorable conditions for the development of this fungus. The cut branches can be used in centerpieces, wreaths, and as accessories on wrapped packages.

If you are planning to purchase a live Christmas tree this season, give careful thought to the selection and care of your tree. In choosing a tree, it is important to know its growth habits. Most of the pines, firs, and spruce trees sold as Christmas trees will reach a height of forty to one hundred feet and a width of ten feet or more. Avoid placing your live tree inside too early. Most potted trees do best if kept inside no longer than one week. Place it near a window away from heating vents, keep the soil slightly moist, and mist the foliage often. It is a good idea to dig your hole before the ground freezes, making sure that it is large enough for the root ball. When planting the tree, place it at least twenty feet from the side of any building, structure or plantings, water it well. Keep the soil moist if rain is lacking throughout the winter and the soil isn’t frozen?

Try using calcium chloride or sand instead of rock salt for deicing your walkways and driveways this winter. Rock salt (sodium chloride) has several disadvantages when used as a de-icing agent. Most importantly, it changes the structure and chemical makeup of soils that it washes into, and is harmful to the plants around areas where it is used, causing injury or even death.

Inspect holiday plants like poinsettias, chrysanthemums, and ornamental peppers for whiteflies before purchasing them. Look for tiny, white, moth-like insects flying from the plant when you touch it. Heavy infestations produce a cloud-like swarm when the plant is shaken. Whiteflies suck sap from the plant causing leaves to yellow, shrivel, and drop prematurely. Whitefly larvae are small, white to yellow, and can be found on the undersides of the foliage. Nymphs secrete honeydew which attracts ants and can lead to sooty mold growth. If you suspect one of your plants has whiteflies, separate it from other houseplants. Insecticidal soaps can be used to control this pest, but you may have to apply it repeatedly for several weeks.

Woody and perennial weeds can be controlled now by spraying their foliage with glyphosate or triclopyr. Plants are moving sugars from their leaves down to their roots, and the herbicide will be moved as well, killing the root system of the weed and eliminating the chance for regrowth. Don’t spray unless winds are calm. Nonselective herbicides like these could kill any plant that comes in contact with the spray, so be extremely careful. In a tight spot, apply the herbicide with a paint brush or sponge attached to a long stick.

Remember that stressed plants are more prone to disease. Be sure that your plants are in the proper location and have adequate light, water, and nutrients.

Dogwood trees can succumb to a fatal fungal disease called Discula anthracnose. The fungus spreads in cool, wet spring and fall conditions. Summer drought stresses trees so they are more susceptible to attack. Early symptoms occur on the leaves and, if left unchecked, the disease can spread into the twigs and branches resulting in cankers. To help prevent the spread of this disease, promptly dispose of all fallen dogwood leaves.

Flower flies, also known as hover flies, are important late season pollinators and predators in your garden. The tiny adults, which look like bees, are easy to see with their bright orange, yellow, and black markings. They feed on pollen and are especially attracted to asters, marigolds, goldenrod, and blue mist shrub. The immature larvae are brightly colored red, orange, and green maggots. They have a ferocious appetite for aphids, rivaled only by ladybird beetles and lacewings.

Flower flies, also known as hover flies, are important late season pollinators and predators in your garden. The tiny adults, which look like bees, are easy to see with their bright orange, yellow, and black markings. They feed on pollen and are especially attracted to asters, marigolds, goldenrod, and blue mist shrub. The immature larvae are brightly colored red, orange, and green maggots. They have a ferocious appetite for aphids, rivaled only by ladybird beetles and lacewings.

Bring your houseplants inside when night temperatures drop below 45°F. Most houseplants are from tropical climates where the average temperature during the coolest month is 64°F. Before moving them inside, spray your houseplants with a 1% horticultural oil solution to prevent insects or eggs from making their way into your home.

Look for signs of juniper webworm on junipers. The adult moth can lay 50 to 130 eggs in the late summer. During early fall, caterpillars mine the leaves on the inner foliage of the plant. This feeding is difficult to see because the caterpillars do not reach maturity until the onset of winter. It is important to act now if your junipers are heavily infested since most pesticides do not adequately control the caterpillars in the spring when they do most of their damage. In serious infestations, the mature caterpillars cover branches with their webs and eat most of the interior foliage. Carefully check interior foliage now, separating the branches to look for silk webbing and, small tan caterpillars with brownish red stripes. Prune out the webs and brown foliage. If caterpillar populations are high you may want to apply a pesticide containing Bacillus thuringiensis (Bt).

Pay close attention to your azaleas now to prevent ghastly yellowed and stippled leaves caused by the azalea lace bug. The lace bug feeds on the underside of leaves, but damage is apparent on the upper surface. Lace bugs leave cast skins and black, gummy, varnish-like feces on the underside of leaves. They deposit eggs, cemented with a brown crusty material, near leaf veins. Warm temperatures cause the eggs to hatch, usually in May. The damage becomes more visible as successive generations hatch in June and July. The lace bug thrives on azaleas grown in the sun; it falls victim to spiders on azaleas properly grown in the shade. Insecticidal soap, horticultural oil, or a systemic insecticide help to control this pest.

Determine the damage threshold for your plants. Decide ahead of time how much injury you can tolerate and don’t take action until this level is reached. Premature measures, taken when they are not necessary, may lead to a resurgence of another pest or harm beneficial insects, mites, and spiders.

Have you heard of an insect with a 13 or 17 year life span? We usually think insects are short-lived, but the periodical cicada can live longer than your cat or dog! Unlike many pests, the adult cicadas don’t feed on leaves, but cause damage by depositing their eggs in the bark of trees. The females saw into the bark of small branches, splintering the sapwood to make slits for their eggs. Damaged branches break off easily in a storm or high winds. Once the eggs hatch, the nymphs drop to the ground, burrow into the soil, and remain there for the remainder of their development. Nymphs suck sap from the roots of trees, but not enough to inflict serious harm. Keep your eyes open for dead twigs and branches. Trees showing conspicuous damage from egg laying include oak, hickory, ash, and dogwood. Mature, established trees usually recover from the damage. Small and newly planted trees may be seriously injured or killed. Protect them by covering them with netting.

Your garden will benefit from your knowledge of what insects populate it. Monitor your garden frequently to find small pest populations before they become destructive. Look for beneficial insects that are feeding on the pests, too. Their relative abundance is a key component in making accurate decisions on whether or not pesticides are necessary. For example, if you observe many beneficial insects and small numbers of pests, you may need to do nothing. Problems usually will not become severe if you notice them early and keep an eye on them. To find small numbers of small insects and mites, place a sheet of white paper under a branch or plant and tap the foliage so these tiny creatures fall onto the paper.

Watch for powdery mildew on your dogwoods. It is a serious disease that stunts new growth and stops growth entirely if severe. Unlike most fungi, powdery mildew does not require water on the leaf surface for spore germination, so it will invade even in dry weather. Neem-based pesticides or horticultural oil will cure the problem.

It’s not too late to plant some vegetables! Plant summer squash in late June to avoid the squash borer. You will miss the prime time for borer damage. The borer feeds in the stems in early summer and completes its life cycle soon after. A late planting of tomatoes and peppers will provide a bumper crop this fall and will avoid diseases that are damaging in hot, humid weather. These plants won’t set fruit during high summer temperatures, but the large plants will produce loads of fruit when nights get cooler in late summer and early fall.

Reduce water usage on your lawn in hot, humid weather. Your grass will go dormant if allowed to dry out and will escape diseases that are common during summer months. Remember to mow high to choke out weeds and let clippings fly to recycle nutrients and reduce the need for fertilizer.