How to be your own plant doctor when it comes to yard & garden pests

Maybe you’ve got the irrigation thing down. You know when to fertilize. You’ve even starting deadheading your annuals and you’re feeling pretty good about how full your containers are with more blooms than last year.  And then something unexplainable happens. Your lawn begins to die in streaky, irregular patches. The leaves on your roses look like Swiss cheese. Or the foliage on your favorite perennial have tiny, pinprick size yellow spots on the underside of the leaves.

It can be incredibly frustrating, especially when you feel like you’ve done everything right. So here’s what to look for with the 4 most common yard and garden pests and what to do next:

1. JAPANESE BEETLES

What are they?

Widely considered one of the most damaging and hard to control pests in the garden. Adults have oval-shaped metallic green bodies and bronze-colored wings. In midsummer when eggs hatch, young grubs emerge ready to feed. See #2 below for more information on grubs.

How to spot the problem

Adults feed on more than 300 species of plants, ranging from roses to poison ivy. They begin on the upper surface of foliage, chewing out tissue between the veins and giving the leaf a skeletonized appearance. You may also notice large, irregular holes in the leaves. Odor and location in direct sunlight seem to influence the beetle’s plant selection. From midsummer into late autumn, grubs feed on the roots of various plants and grasses, often destroying large patches of lawn.

How to control them

As with most pest infestations, early prevention is your best line of defense. Here are some things to keep in mind at any stage:

• Maintaining hardy, healthy plants is one of the best defenses against infestation.
• An application of Bayer Advanced Tree and Shrub Insect Control in May is normally a very effective deterrent, as is Carbaryl and Eight. Several applications may be necessary during the active stage.
• Rose Pharm Insecticidal Soap, an organic solution is a contact control that requires multiple applications. Do not apply during the heat of the day to avoid potential damage to foliage.
• Try Milky Spore or Kill-a-Grub to limit the number of beetles you encounter next spring.

2. GRUBS

What are they?

Japanese beetles are often blamed for grub problems when the truth is, grubs can actually be the larvae of several different beetle varieties. Why all the fuss? The beetle larvae happen to feed on the roots of turf grass and other plants, sometimes wreaking major havoc on otherwise healthy lawns and plants.

How to spot the problem

Irregular dead spots caused by beetle larvae feeding on grass roots. Damage is worst in the fall. Dead turf pulls up easily, like a rug, revealing curved c-shaped larvae. Animals like gophers, moles and skunks will dig up lawn to feed on grubs.

How to control them

The key to controlling grub damage lies in understanding their life cycle. As with many gardening practices, timing can be everything.

• Grubs over-winter deep in the soil.
• Larvae move up toward the surface in spring as the weather and soil warm, eventually pupating into adult beetles. Because they are not feeding at this point, insecticides are rarely effective.
• Adult beetles generally begin to emerge in early summer and begin feeding on foliage and fruits. By mid-July, adult will lay eggs that hatch into small larvae. The larvae begin feeding in early August. This is the optimal time to apply insecticide.
• Young tiny grubs are most easily controlled.
• Always remember to water in your insecticide for optimal results and follow package label instructions.
• For best results, we recommend not using the same insecticide every year.

3. SPIDER MITES

What are they?

Less than 1mm in size and in virtually as many colors as there are plants, the spider mite typically lives on the undersides of leaves, often spinning protective silk webs and puncturing plant cells to feed. The most common outdoor mite is the Spruce Mite, but it can be found on perennials, shade trees, evergreens and shrubs. You may also find certain species on houseplants.

How to spot the problem

Normally the first sign of spider mites is a mottled or pinprick yellow discoloration on the undersides of leaves. A simple way to test for mites is to place a white card under browning foliage. Lightly tap or shake the affected leaves or branches. If mites are present, you will see small, pinpoint spots moving across the card.

How to control them

If spider mites are present, control should begin early in the growing season to prevent the buildup of a large population.

• Mites typically start hatching when temperatures warm up to the 40 degree Fahrenheit mark in early spring, catching them early means they won’t potentially make it through resting stage in hot weather only to reemerge in the cooler conditions of fall.
• Control can be achieved with a miticide or a multi-purpose insecticide such as Eight.

4. BAGWORMS

What are they?

Bagworms are caterpillars that live inside highly camouflaged, cocoon-like bags spun of silken thread. As they feed, bagworms add bits of foliage to the bag, increasing its size up to two inches.

How to spot the problem

Bagworms can be devastating to evergreen trees (especially Arborvitae, Junipers and Spruces) because each female has the ability to produce up to 1,000 eggs. Bagworms hatch in early to mid June and stay active through August.

The first sign of trouble is thinning or browning foliage. Upon closer inspection, carrot- or cone-like bags (often mistaken for pinecones) can be found throughout the shrub or tree. Mild infestations can slow growth and heavy infestations have the power to kill evergreens.

How to control them

Once again, early prevention is your best line of defense. Here are some things to keep in mind at any stage:

• Remove egg-containing bags from September through June to prevent future hatch cycles.
• For highly susceptible or previously infested plants, play it safe with an early-spring application of systemic insecticide such as Fertilome’s Systemic Insect Drench.
• BET and Spinosad can be applied throughout the lifecycle of the bagworm, and other insecticides like Eight and Carbaryl can be effective on young bagworms with bags/cocoons under one inch long.

 

If you’re still not sure what you’re dealing with, bag up a sample and/or bring in a photo or two and a landscape professional in the garden center can help you identify the problem and share recommended next steps.