Natural Strategies to Control Garden Pests
As you cultivate to keep your bit of the earth in good health, a shift may occur in how you think about the creatures large and small that inhabit your bit of the world. In this article, we’ll discuss in detail some natural strategies to control garden pests and help you understand more of the ecosystem in your garden.
From microscopic mites and a plethora of insects to voles and deer, there is a place in your backyard habitat for all of them.
This goes even for the evil little squirrels, though I will continue to curse them when they hit me in the head with green crabapples!
I want to encourage you to increase the diversity of plants and avoid using pesticides randomly in your garden in order to improve the habitat for critters of every sort.
Remember the four pillars of healthy habitat and provide places to nest and rest along with water and food resources. If you do these things, nature will take its course and you will have fewer bad bugs because there will be balance in the habitat.
Keep clippings and deadheaded flowers raked out of the beds, and mow the areas where it’s tempting to let weeds take over.
Remove those safe harbors for pests, take a brisk walk around the garden every day so nothing gets by you, and reduce or eliminate the use of pesticides, including the organic controls. Of course, there will be pests, but thrifty plants in gardens where beneficial insect populations can thrive will always be less vulnerable to serious damage from them.
Take it on faith, or try it for a year and see for yourself.
Beneficial Insects: Our Garden Angels
Not every critter, bug, or fungus will kill your plants. Think tolerance first. So long as they’re not eating your plants, leave them alone. Some are simply a nuisance you can ignore or deal with, although it may mean putting up a fence against deer or rabbits. The garden angels, though, are your best friends because they feast on the bugs that eat your plants. Look for these beneficial insects and cultivate your microclimate to encourage them.
Ladybird Beetles (aka ladybugs)
Ladybird beetles (aka ladybugs) have the advantage of being colorful and not at all threatening-looking. Spots dot their orange-red backs as they scurry around on your plants, merrily dining on aphids, scale insects (especially the crawlers, yum!), spider mites, and mealybugs. This family of insects is huge, and most are helpful. But there are bad relatives. If you spot one with a bronzy color back (Mexican bean beetle) or three neat rows of black spots on a yellowish back (cucumber beetle), you’re under attack.
True bugs are a group you can watch work to know whether they’re at work, beneficially. Larger than most of the pests, this posse romps quickly through the plants. They stick their victims and suck out their bodily fluids. Nasty to think about, but these very effective predators can only work if you let them alone. This may sound stupid, but before you pull out the pesticide, even the insecticidal soap, be sure the bug you see is actually eating a plant, not another insect. Watch for the well-named members of the predator posse:
- Assassin bugs have red bellies and seek out aphids and leafhoppers.
- Damsel bugs have long front legs that pinch their soft-bodied prey.
- Pirate bugs are painted in harlequin patterns, but are mostly beak, and are the nemesis of thrips.
Braconid wasps look like white spikes stuck to their prey, which includes tomato hornworms, aphids, and leaf rollers. Learn to love this sight, since it means you don’t have to get out the BT to control many caterpillars.
Tachinid and Syrphid Flies
Tachinid and syrphid flies are in the hoverfly group, so named because they fly like a helicopter. The T’s are also called sweat bees and do mimic bees and wasps in appearance. They’ll eat almost anything, including stinkbugs, thank goodness. Syrphids look like little wasps, but let them be so their maggot babies can eat up the aphids in your garden.
Praying mantis, those angular green jewels, are not the most efficient of the predators, as they will eat aphids and unfortunately other predator insect larvae as well, but deserve to be left alone in most gardens.
Lacewings might be the most overlooked of the beneficial insects and could be called the swans of the garden. The adults are lovely with mesh green wings dominating a tiny body. But the ugly duckling immature stage, the voracious lacewing larvae, are decidedly fierce-looking, almost reptilian in demeanor. One’s first instinct might be to squish the ugly things, yet you must resist. The lacewing larvae are called ‘aphid lions’ for good reason.
Spiders and Toads
Spiders and toads are obviously not insects, but they benefit the garden greatly if you allow them to live in it. Daddy longlegs, jumping spiders, and many more eat any sort of insect they can catch. Toads are the slow and steady predators in your garden. They keep their area clear of pests, so if you’re lucky enough that one has burrowed into the garden, give him a name and thank him for his work.
Integrated Pest Management
Each pest-control strategy outlined in this article is based on the principles of IPM. This approach keeps in mind the big picture, the garden’s overall ecology while offering a path to follow that helps to keep it in balance. To practice integrated pest management, keep these principles in mind:
- Choose plant varieties with known tolerance for common insects and diseases.
- Set up traps in the garden, both to capture insects and let you monitor their population whether good or ill.
- Observe your plants daily, or walk the garden every day.
- Look for changes in growth patterns, egg masses, or chewed leaves, but don’t miss the first flowers and honeybees, either.
- Identify insects, mites, and symptoms of disease; do your research.
- Determine the extent of the damage and monitor it, but also note the actions of predatory insects and the limits of your distress.
- Don’t overreact. Physically remove insect pests with your hands or a strong stream of water. Rake up fallen diseased leaves and do not compost them. Cut down weeds near stressed plants and attend to their needs for water and fertilizer.
Proceed with caution, aware of the impact of pesticide on the entire garden, not just one plant. Ramp up to controls that are organic when necessary to save plants from being overcome by pests, if the plants are valuable to you and if the controls have a reputation for working.
Know when to say when, and simply remove plants that cannot be grown without extensive pesticide intervention. This will help you develop the best natural strategies to control garden pests and simultaneously help you build a stronger future for your garden.
Those Pesky Little Devils
Some critters are hard to tolerate. Consider the rabbits, deer, armadillos, possums, voles, and moles. In cultivated areas of your property, a fence is the best way to exclude the first quartet of marauders.
You can chase the rabbits out of the collard patch like my mother did, or hang up bars of soap to deter the deer or spray daily to repel them. Don’t give the armadillo or possum away into the barn or greenhouse. They’ll get a postbox and you’ll never be rid of them. And don’t overlook the importance of removing food and water sources. Pick up the food and water bowls each evening if you feed any animals outside.
When it comes to voles and moles, there are enough solutions to fill a dumpster, though few are worth anything. Voles are little rodents a couple of inches long, mostly tail. If they have their druthers, they will burrow in the nice loose garden soil in your beds, eating plant roots until they can raise a family and eat the rest of your roots.
Some gardeners will advise you to try and poison them, others say to tamp down the soil and/or increase or decrease the amount of mulch you use. The most effective vole control is having a cat who is allowed to hunt them. Yes, I advise pitting the voles against a cat. They will lose and the survivors will move next door.
Before the gentlest among you complains, I am acutely aware of the issues involving cats and gardens, but vole control is their forte. I do not have bird feeders in my garden yet plenty of birds find it anyway, as do squirrels, lizards (superior gnat eaters, by the way), and occasionally, my neighbor’s pot-bellied pig.
We’ve established a certain rapprochement over the years and I encourage you to tolerate all the animals you can, too, in the name of eco-diversity and easier gardening. The squirrels keep to the oak trees that dot the property, while the birds nest in a thicket, in the shrubs and trees around the garden’s edge.
The lizards hang out in the kitchen sink planted with aloe vera, dashing to the rooftop whenever the cats emerge from their sleepy stupor to patrol the courtyard. The felines make their way about the garden to sleep in the shade under a rosebush or tomato plant. It works for us.
Moles drive people crazy all out of proportion for the damage they do. I’m not downplaying the ruined lawn nor my father’s serious attitude about them.
However, the extreme lengths people go to often show the little result, and that frustration is, I think, what deranges homeowners. Yet there are solutions. The raised runs created by moles are the key to disrupting them, along with controlling the grubs they seek in those tunnels they make.
At the first sign of a run, stomp it down. When it reappears the next day, stomp it down again, or shove a garden hose into it and turn it on full blast. This is also the place to set the trap if you use one, but no, there are no live-catch traps for mole hunting. Metal rods with spinning whirligigs atop them are often stuck into the runs on the theory that their vibration upsets the moles. Might be, but the sight of a dozen or two of them in one yard isn’t my idea of art. Control the grubs, stomp the runs, and worry about something important.
Bagworms and Webworms
Some of the ugly pests and their bags and webs are best removed, even if it takes a bit of imagination to figure out how best to do it. Webworms and bagworms are clever rascals who spin a cover to protect their nest and sit happily inside. You can drench the tree in insecticide and it never touches them, but there are two strategies that usually work better. To whatever height you can reach, pluck off the bags. Use a broom wrapped in cheesecloth or something similar to collect the webs.
For unreachable heights, use the strongest blast of water you can muster. There are hose attachments including long pipes to focus a blast strong enough to flake paint, and they knock the webs down, too. When the webs are breached the birds can work on the worms.
The real marauders in your garden are pests that work against your best efforts, and sometimes take advantage of your good intentions. Most plants can tolerate some pests for some time, and you shouldn’t feel bad about the occasional ruined leaf. If you don’t want to control insects, grow plants with bulletproof reputations.
Left uncontrolled for too long, each of these pests can kill the plants they inhabit. There are other pests, of course, with equally venal intent to particular plants, but the ones in this group are quite common to many plants. When you do have a plant under attack from insect or fungus pests, decide first if the plant is worth saving. If it is, use physical controls first, then target the plant with an organic pesticide that will control the problem, and treat only that plant if possible.
Piercing, Sucking Punks. This Group Drains Your Plants.
Aphids have soft bodies about the size of a pinhead. They’re round or pear-shaped and come in different colors depending on their lifecycle stage and what they’re eating. Aphids multiply every eight days and populations can build geometrically as they dehydrate the new growth of almost any available plant, often resulting in pale, dry-looking leaves. Worse, plants can be stunted and even die.
Look closely at the aphids on your plant; if they are swollen and goldish colored, celebrate because natural predators are at work. Likewise, if you have aphids but also a large population of the beneficial, the natural balance may be enough to keep the damage at a minimum.
Most plants can take a few aphids, and it’s counterproductive to lose those feeding on them by using insecticides, whether organic or chemical formulas. If you see ants traveling about on your plants, control them because they farm the aphids, sheltering them from natural predators. To control both ants and aphids, the first blast affected plants with strong streams of water daily. If the aphids are still visible after two days of water torture, treat immediately and every eight days with insecticidal soap spray or spray or dust with a contact organic insecticide such as pyrethrin.
Whitefly is a winged insect a quarter to half an inch long. Its tiny young are non-airborne, white specks seen on leaves and stems, especially on the undersides. Seriously infested hibiscus, gardenias, and other shrubs will yellow and their growth will stunt.
Space new plants and prune established ones to provide good air circulation, and fertilize, but do not overuse nitrogen where whitefly is a problem. Remove plants that harbor whiteflies such as little leaf privet and golden euonymus. Their presence there may not be an issue, but subsequent infestations on gardenia or crepe myrtle nearby can be.
Young whiteflies can sometimes be dislodged with a blast of water, but usually, they stick tight. This stage is not mobile, so insecticidal soap or pyrethrin sprays will control them. Since the adults fly away as you approach, spraying them directly is difficult. Sometimes they congregate on the plant at dusk, so a blast of water may drown some. Pyrethrin or rotenone dust will have some residual effect while it is on the leaves. As a last resort and to save a particularly valuable tree or shrub, conventional advice would say to use systemic insecticides.
However, there are no organic systemic insecticides. The systemic strategy that introduces the insecticide into the plant’s system also puts every insect at risk of being poisoned. Especially indoors, some people have good luck with yellow sticky paper, which not only traps the bugs but helps you monitor population buildups and guide your control efforts.
Leafhoppers can move both sideways and straight up. In addition, the adults can fly. Most often we see small multicolored wedges that jump right out of the way when disturbed. Young and adults dehydrate plants, particularly shrubs like azalea. When the population surges, leaves look mottled and may turn brown with curled edges
Look for the signs of the first leafhoppers in early summer, shiny, brownish-orange dots of excrement. Annually, rake out the mulch under shrubs and replace it to destroy their nests. Introduce green lacewings and practice good garden sanitation. Use oil sprays in winter and early spring. Treat at the first signs of damage with pyrethrin or neem sprays.
Scale Insects Strategies
Scale insects look quite different on different hosts, but adults are lumpy shapes coated with waxy protective shells. You’ll see various colored bumps on stems, bark, and/or leaves that look positively disgusting. Leaves on camellia, Japanese magnolia, and other trees and shrubs can turn yellow and mottled when scale are feeding. In early spring, the crawler stage of scale hatches and searches for the perfect place to insert its beak and grow up. All stages cause twisted new growth, disfiguring the plant and sometimes killing it.
Since adult scales are almost impervious to pesticide sprays and are too stuck to the plants to be blasted off with water, winter oil sprays are essential. When you identify the insect, usually in summer, scrape off all you can from large branches and prune out any small colonies on little branches and stems. Destroy all material you remove, then spray the plant with insecticidal soap to finish them off. Use oil spray in winter, then keep an eye out for the crawlers to hatch with the first new leaves on the plants. Spray them with neem at weekly intervals as long as you see new hatchlings.
White Grubs Strategies
White grubs, the larvae of June bugs and Japanese beetles, spend the winter under the lawn. Both kinds wake with the spring and feed their voracious appetites by eating grassroots on their way to emerging from the surface. The grass looks streaky and yellow, often in stressed areas or near concrete driveways, and has lost its roots. When it peels right off the soil surface, it’s dead. Adult June bugs seldom do enough damage to plants to warrant control, but Japanese beetle adults can defoliate your rose garden in a day.
Look for the adults and determine whether June bugs or Japanese beetles are present in the summer garden. Pick off the adults, or lay a sheet under the affected plants and shake the plants in the early morning to knock the sleepers off where you can dispose of them easily. Use rotenone dust if necessary to control Japanese beetle adults and treat the lawn with milky spore yearly.
This naturally occurring disease takes a year to be effective, but long term, it is the way to go. If June bugs are an issue, treat the lawn with parasitic nematodes. Japanese beetles are limited to one generation per year, fortunately, since they are capable of stripping an entire rose bush while you’re away for the weekend. Their brief life happens in summer, and when they are sated, they mate and lay eggs in the soil. The grubs are shaped like the letter C and are the tasty morsels sought by the moles that tear up your lawn.
Chinch Bugs Strategies
Chinch bugs are marked with a white crossways stripe on the back of their red or black, quarter-inch long hard bodies. They take advantage of dry conditions in lawns to set up residence. The turf doesn’t peel up as it does with white grubs but does turn yellow first and then brown.
The damage proceeds in an increasing circle; the appearance can be similar to lawns attacked by brown patch fungi, but its areas wax and wane with rainfall. To confirm the presence of a chinch bug, cut both ends off of a coffee can or other similar cylinder and plunge it into the soil at the outer edge of the damage. Leave half of the can above ground and fill it with water to check for them+. Chinch bugs will float to the top.
Soak lawns at least occasionally to keep blades and thatch healthy. Fertilize annually and mow at the recommended height for your kind of grass. Specifically, mow your turf often enough to maintain the following heights without removing more than one-third of the leaf blade in one mowing.
- Bermuda 1-2 inches.
- Zoysia 1 1/2 to 2 inches.
- Centipede 2 to 2 1/2 inches.
- St. Augustine 2 to 4 inches.
Note: Mow common Bermuda and common St. Augustine at the higher end of the range; keep improved varieties lower. Remove grassy weeds from your property because they can harbor chinch bugs, too. It’s time to dethatch if the lawn feels spongy when you walk on it. This process is laborious and the lawn looks bad for a few weeks until it recovers. Use insecticidal soap sprays and rotenone to control chinch bug populations as soon as you find them.
Fungi Alert: Rusts and Molds
The list of pathogens that can attack plants is long and their life stories equally complex. My list is limited to the most common.
Sooty Mold Strategies
Sooty mold looks like its name. This flaky black coating covers all plant parts when it grows on them. Its preferred host is the sugary excrement of piercing and sucking insects, so it is found below them on the plant or on other surfaces under trees such as lawn furniture. It is most unattractive and can make sitting spots sticky, ruin flowers, and, most seriously, interfere with basic plant growth.
Remove sooty mold from plants with soapy water spray. In the case of concrete and furniture fabrics, scrub with manufacturers’ recommended cleaning products. In the long run, however, prevent sooty mold by controlling the insects that provide its food, removing the conditions that favor its growth.
Rust, contrary to popular culture, does sleep. But the orange fungus waits for rainy, warm springs and then erupts, dotting iris and daylily leaves on their undersides. The dots soon turn into streaks, then entire leaves turn yellow and fall off to lie in wait in your mulch.
Crowded plantings encourage rust outbreaks in many species. Dig and divide plantings at three-year intervals or whenever the leaves become so dense that you cannot see the ground. Clean up perennial beds every fall. Remove all fallen leaves and debris, work the old mulch into the ground and replace it. When rust appears, remove all infected leaves from the garden, and dust new growth with sulfur or spray with fungicide until fully emerged.
Root Rot Strategies
Root rot is caused by several pathogens usually present in our soils but can be imported with new plants or soils. Most woody plants can be susceptible, particularly holly and magnolia species. Flooding or constantly wet root zones exacerbate the issue for any plants that require good drainage to perform up to their potential. New shrubs can fail to grow and leaves may yellow all over the plant. Older plants infected with root rot wilt suddenly without dropping leaves.
Understand the needs of the plants in your garden. Prepare new beds or planting sites to insure drainage adequate for that species. Avoid overwatering and dig a shallow ditch to divert floodwaters away when needed. If you suspect root rot and have altered the water profile around the plant, prune it by half. Drench the soil with a fungicide and spray new growth as it appears. Alternatively, dig up the plant, improve and treat the soil, then replant.
And there you have have it, a solid start to understanding more natural strategies to control garden pests, from bagworms to root rot.