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The Low-Maintenance, Organic Way to Deal with Pests

Carol Allen may be a plant geek, horticulturist and organic gardener, but she’s also a self-professed LAZY gardener.  So when she teaches her favorite ways of dealing with garden pests, you know it’ll be the most effective, easiest to do, and also the easiest on the environment. Here are the highlights of her talk at our Beltsville store on this favorite subject of hers.

ladybug larva
Ladybug Larva

The Best Defense?  Healthy Plants

  • So put the plants in the right place, which starts by giving them the amount of light they need.   Since most of us overestimate the sun we get, it helps to check several times a day and note the actual number of hours.
  • Test the soil, at least for pH. The test is cheap and easy and ensures that your plants get the nutrients they need.
  • Add plenty of organic matter.  Carol’s favorite is her own homegrown compost, followed by locally made Leafgro compost.  She keeps some bags on hand at all times.
  • Water correctly. That means no broadcast spraying – plants need a long drink, not a quick shower. The water has to get not only to the rootball, but also saturate it. Correct watering is deeply and thoroughly, not frequently and shallowly.
  • Mulch for plant and soil health.  For veg gardens she loves straw mulches but for trees, shrubs and flower beds she uses shredded bank or her own cropped-up dead leaves.  Why waste ‘em?
  • Don’t over-fertilize! Research at the University of Maryland and elsewhere is showing that less is more – it prevents fertilizer from running off into the Bay and killing our crabs.  (Speaking of which, crabshell-based fertilizer is excellent!)  Carol uses little to no fertilizer in her garden but when she does feed, she uses Espoma’s line of organic products.  They feed slowly and safely.

Best Methods for Dealing with Pests

  • Prevention – using that list above.
  • Knowledge – identify the pest before deciding on a “treatment,” if any.  Two great sources to help with that are Va Tech and the University of Maryland.
  • Barriers, like floating row covers
  • Mechanical removal
  • Encouraging beneficial insects
  • Chemical controls, especially spot-spraying with safe organic products (yes, organics are chemicals, too.)
  • And take notes so that next year you have a chance to prevent the problems you’re dealing with this year.

Recognizing some of Gardeners’ Best Friends

Sure, we all know that ladybugs (more properly called ladybug beetles) eat destructive insects like aphids, but do you recognize this little guy?  It’s the ladybug beetle’s larvae and they’re “bug-eating machines”!

For the green lacewing (below), it’s the same story.  Those babies don’t look like much but they’re great workers in the garden.

Lacewing Adult and Larva

pests soldier beetle and assassin bug
Soldier Beetle (L) and Assassin Bug (R)

More good-guy bugs include spiders, yellow jackets, parasitic wasps (which plant their eggs IN aphids!), syrphid flies, and wheel bugs.

How to Attract Beneficial Insects?

Grow a diversity of plants.  Especially among vegetables, it’s important to grow a variety of these flowers that do a great job of fighting pests on your edibles:  carrot, yarrow, Queen Anne’s lace, zinnia, ageratum, sweet alyssum, blanket flower, cosmos, sunflower, tansy, marigold, aster, daisies, mums, black-eyed susan, coneflower, coreopsis, bee balm, salvias, nasturtiums, and poppies.  Plus, these herbs: mints, dill, fennel, coriander, parsley, anise, thyme, sage, oregano.  This is generally the same group of plants that attract butterflies.

Organic Pesticides

  • Horticultural oil like All Season Horticultural Spray Oil works by suffocating the target bugs, but make sure you get the spray on their bodies. Hort Oil is effective in controlling cucumber and bean beetles as well as on ornamentals for scale insects. Be sure to follow the temperature requirements on the label, to avoid burning the plant’s leaves.
  • Neem oil like Schulz’s Fungicide (that’s the product name, but really a multipurpose spray) is another good one for general use.
  • Horticultural soaps are products Carol doesn’t use as often because they kill only larvae and are less effective on adults, while oils kill both. Also, they sometimes burn leaves.
  • Bt (Bacillus thuringiensis) is a naturally occurring bacteria that messes with the digestive system of caterpillars, causing them to die of starvation. Asked how to use this product without killing the caterpillars we WANT (butterflies especially) Carol explained that Bt should be used selectively on just the plants that are being fed on by the target insects (like for cabbage worms). So for example, you wouldn’t spray it on parsley or pawpaw trees because they’re fed on by butterfly larvae.
  • Spinosad, contained in Captain Jack’s Dead Bug Brew, works on beetles, caterpillars, sawfly larvae, and soft-bodied insects. It’s another naturally occurring bacteria. Carol recommends it for such ornamentals as roses and Mugo pine.

Next, Carol highlighted some of the worst pest offenders, and what to do about them.

pests tent caterillar's egg mass
Tent caterpillar’s egg mass, and caterpillar-filled tent

Eastern Tent Caterpillar

This native caterpillar feeds on cherry, apple trees, and serviceberries and can be vanquished easily if you spot the black egg case in winter. Just rub it off of the twig or branch it until it drops to the ground. If you miss it, you can’t miss the caterpillar-filled tent that appears in the crotch of target trees in the spring – remove that with your gloved hand and send it off with the trash.

Eastern Tent Caterpillar

This native caterpillar feeds on cherry, apple trees, and serviceberries and can be vanquished easily if you spot the black egg case in winter. Just rub it off of the twig or branch it until it drops to the ground. If you miss it, you can’t miss the caterpillar-filled tent that appears in the crotch of target trees in the spring – remove that with your gloved hand and send it off with the trash.

pests typsy moth egg mass, aphids, and cabbage worms
From left, Gypsy moth eggs, aphids, and cabbage worms

Gypsy Moth

These voracious eaters are doing great damage to our trees, especially oaks.  If you spot their egg mass in the spring, just scrape it off with a putty knife, bag the mass and throw it away.


Aphids come with a leg-up in the survival sweepstakes of Nature – they’re born pregnant!  The best way to deal with them is to simply wash them off, and attract those great aphid-eating beneficial insects.

Cabbage Worms

If you grow vegetables in the cabbage family, you’ve probably battled these little crop-eaters.  They’re best prevented with the use of row covers, or by spraying with Bt.  Sure, they can also be removed by hand but it’s hard to stay ahead of their munching.

pests japanese beetles and brown marmorated stink bug
Japanese Beetles and Brown Marmorated Stink Bug

Japanese Beetles

Introduced to the U.S. in the early 20th century, Japanese beetles are kinda fun to hand-pick and drop in soap water but can be largely prevented by spraying milky spore on your lawn. – because lawns are where the grubs live for most of the year. Just don’t buy traps for them – they only attract MORE beetles to your garden.

Brown Marmorated Stink Bug

This is a newcomer to our gardens, having been discovered just 14 years ago, but it’s rapidly becoming a major pest here in the Mid-Atlantic region – even in our homes! So lots of research is being done on this stink bug, especially by the University of Maryland, including on the efficacy of traps. In the meantime, there’s one product Carol recommends – the clay-based Surround. Spray Surround on developing fruit such as tomatoes, peaches, and apples to protect them. It’s also a good idea to clean up the vegetable garden before winter, to reduce the chances of wintering-over pests – not just this stink bug but many others that could emerge in the spring to eat your crops.

Lacewing larvae photo credit. Lacewing adult photo credit.  Ladybug beetle larvae photo credit.  Soldier beetle photo credit.   Assassin bug photo creditTent caterpillar photo credit. Gypsy moth photo credit. Aphid photo creditCabbage worm photo credit. Japanese beetle photo creditStink bug photo credit.

Stephanie Fleming was raised at Behnke’s Nurseries in Beltsville. Her Mom, Sonja, was one of Albert & Rose Behnke’s four children. She was weeding from the moment she could walk and hiding as soon as she was old enough to run, so many weeds, so little time. Although she quickly learned how to pull out a perennial and get taken off of weed pulling duty.

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