Under attack

Gardeners face many of the same challenges as farmers - only on a smaller scale. They have to contend with whatever Mother Nature throws at them, from drought to flood, scathing heat or frigid cold, but to top it off, there are insects, diseases and animals.

Now that the garden season is at its peak, problems are also rising.

Gardeners should walk their gardens, if not daily, at least once a week. The idea is to notice trouble before it becomes a big disaster.

Some insects and diseases create similar symptoms, so properly identifying what’s wrong is important. If problems are occurring over a vast group of different types of plants, chances are the cause is not an insect or a disease, since most insects and diseases tend to have specific host plants (or at least they start out on one and then move on to others).

But deer and other animals aren’t as particular; also, an improper application of a chemical will cause damage across plant species.

Insects are the most diverse group of organisms on earth.

There are more than a million described species, and there is not one place that doesn’t have some type of resident insect. Not all these insects are bad. Where would we be without the pollinators that provide us with crops, or the butterflies that beautify the environment? Ladybugs, in their adult and larval stages, eat aphids, and the praying mantis eats good and bad bugs.

But there are troublesome insects out there, and if not controlled, they can kill or ruin your plants. Insects multiply rapidly in warm climates.

The most troublesome species change from year to year. Many yards have been plagued by the variable oak leaf caterpillar this year, in larger numbers than we can ever remember. Some years we have more tent caterpillars in the spring or fall webworms in the fall.

With insects that feed on large shade trees, normally the damage is not life-threatening. Repeated defoliation of young trees can be a different story, but since they are smaller, they could be sprayed if warranted.

Some insects feed on weakened or stressed plants, while others like tender new growth. If you see problems on your plants, you need to determine what the culprit is and then take action.

PHYSICAL EVIDENCE

Insects feed in various ways, so identification should start with the physical damage.

Some have chewing mouth parts, like caterpillars and grasshoppers, which eat holes in leaves or large sections of foliage.

Others have sucking mouth parts, like aphids and lacebug insects. Think of it as inserting a straw into the leaf and then sucking out the plant juices. Instead of holes in the leaves, the foliage is marred with little specks. When enough feeding has been going on, the entire leaf surface is silvery or whitish where the chlorophyll has been taken out of the leaves.

Rasping mouth parts scrape off the top surface of the leaf and then the insect sucks out the sap. Mites and thrips are the culprits here. They are small insects, so the damage is silvery in appearance, but there are no holes in the leaves.

Then there are tiny larvae of insects that feed between the surfaces of the leaves, leaving a trail of tunnels or squiggly lines in the foliage. These insects are called leaf miners, because they are basically mining out the sap in between the two surfaces of the leaves. Thankfully, they usually look worse than they are, and you can cut off the damaged leaves and be done with it.

And lastly there are boring insects, those that can bore holes in trees or the stems of your squash plants. Wood-boring insects usually go after weakened trees, but not always. Once inside, they are difficult to kill, since they construct a series of tunnels; contact sprays are not effective.

Squash vine borer adults are a clear-winged moth that resembles a wasp. The adult female lays eggs near the base of the squash plant. When the larvae hatch, they bore into the stem of the squash plant and tunnel through, killing the plants fairly quickly.

THE USUAL SUSPECTS

If you have holes or chunks missing from leaves, inspect the plant. Sometimes you can easily spot the culprit, but other times you have to investigate. Many insects use camouflage to mask themselves or help them blend in.

There are some common culprits that we see annually on certain plants. If you are growing hardy hibiscus, the mallow sawfly can turn its leaves to lace. Cabbage worms can do the same to members of the cabbage family, and the tomato hornworm can feed on a tomato plant and destroy it quickly.

Corn left unprotected is usually attacked by the corn earworm. Flea beetles are common on eggplants, and slugs love hostas.

So start by looking for the most common complaint.

When grasshoppers hit, it seems like a plague of locusts. They feed on many different plants.

The Japanese beetle is the bane of many a gardener in the northern tier of the state.

Bagworms attack junipers and cedars first, and construct their protective sack out of the plant they are feeding on.

If you can’t find what is out there, try using traps or baits to spot them, so you know how to control them.

Learn to tell the good caterpillars from the bad. If you’re growing parsley and fennel to attract butterflies, it makes no sense to kill their caterpillars. Learn to recognize the larvaeof the good and the bad bugs. APHIDS

Aphids are the rabbits of the insect world. These small insects give birth to living young, and when conditions are right, those newborns begin propagating as well. They can be green, yellow or black and often congregate along the stems or tips of tender new growth. They suck out sap and give off a sticky substance called honeydew. Where honeydew lands, on car windows, patio furniture or plants, a black, sooty mold can form. Aphids attack flowers, vegetables, shrubs and even trees.

Think twice about parking your car under a large shade tree. That sticky residue is probably the droppings of aphids feeding on the tree foliage.

SUCKERS

Other sucking insects that give off honeydew include whiteflies and scale.

Whiteflies commonly attack gardenias. They look like specks of white dandruff flying off the plant. Then the foliage can be covered in theblack, sooty mold. Whiteflies are also a problem on some flowering tropicals, and they can get on vegetables and other ornamentals.

Scale insects and mealy bugs are also common on a wide variety of plants. Camellias commonly get tea scale, while mealy bugs are soft-bodied scales that attack the underside of foliage and the joints where leaves attach to stems.

Golden euonymus is frequently attacked by the euonymus scale.

Scale insects are not going to kill a plant overnight, but left unchecked, they will multiply and gradually weaken it. Scale insects come in all sizes and shapes, from tiny white and black tea and euonymus scale to hard armored scales and white oyster scales. The hard outer coating protects the insect inside, so typically a systemic pesticide is needed.DO IT RIGHT

Whether your garden has insects or diseases, practice good integrated pest management practices. Give your plants what they need to grow- proper plant selection for your site, then the right cultural practices, including water, fertilizer and pruning.

Monitor your garden regularly. Decide how much damage you are willing to live with. When those thresholds are met, take action. Look at what is available to control the pest: physical barriers, sprays of water, pruning out damaged plants, or organic or nonorganic sprays.

Spraying is usually the last resort. But if you spray, make sure that what you use is labeled to control your pest and that you are applying it at the recommended rate. Many home gardeners think that if a little bit is good, a lot will do better, but that isn’t the case.

Gardening can be challenging, but the end results outweigh the work. If you have problems in your garden and you don’t know the cause, take a sample to your local county extension agent. Good photos are also beneficial. Once you can identify the problem, you are on the road to solving it.