When your garden takes off under the summer sun, pests are often close at hand to cash in on the feast. It can be devastating to watch aphids and thrips take over your beloved plants. Snail trails and chomped up leaves are the age-old ire of many gardeners. When pest damage starts to threaten not just the overall health of your plants but also your peace of mind, many desperate gardeners turn to pulling out the full arsenal of pesticides to stop bugs and slugs alike from destroying their hard work.
The good news is that you don't always have to wage war with bugs to co-exist in the garden. Ecological gardening experts like Rebecca McMackin and Doug Tallamy swear by the '10 Step Program' for pest problems:
Take 10 steps back and look around. Does it still look like problem?
Sometimes, the answer is "Yes!" — but, other times, we may need to look deeper into our mindset about insects. All across America, a cultural desire for picture-perfect landscaping has created a huge appetite for pesticides. Homes, gardens, and lawns account for over 50% of insecticide use in the US, often in far higher dosages than are considered safe. Insect populations have declined by over 45% in the past 40 years.
By nature, a garden is a place full of life. Trying to sterilize it from bugs counteracts the natural cycle of life and replaces it with an endless loop of harsh chemicals and heartache. It's important to remember than insecticides impact more than just the 'nasties' — they can also harm beneficial insects that we want to encourage in our gardens. Insects are everywhere for a good reason. They're an important part of our ecosystem, both in nature and within your garden. We tend to appreciate bees and butterflies for pollinating our plants, but insects play a whole host of vital roles under our very noses. Some insects, like hover flies, wasps, and ladybugs, are voracious predators of common garden pests. Even much-maligned aphids provide food for the rest of the web of life, including more welcome garden visitors like birds. As the primary food source for birds, the decline in insect populations has also caused avian numbers to drop. In reality, insects are vital players in life on Earth and less than 2% are actually considered pests.
While it's unrealistic and even detrimental to rid the garden of all insects, we help gardeners troubleshoot frustrating pest problems nearly ever day. Pest damage is a very real problem, but many of us have a visceral aversion to insects. Sometimes, a change in mindset can help us stop recoiling at the sight of bugs and start looking at how 'pests' actually behave: a few bugs may just mean your yard is functioning as a part of nature, while a severe pest infestation is often a sign of an imbalance in the ecosystem. Learning to co-exist with bugs doesn't mean letting them take over — it just means reacting appropriately and finding long-term solutions. Let's explore ways to manage pests in our gardens (starting from the most benign options and working up to more intense solutions), as well as prevention strategies to help you and your garden live alongside insects.
Treating Pests
Manual Control
The gentlest method of controlling insects is to manually remove them from your plants. For small numbers of pests like aphids, you can always squish 'em before their populations get out of control!
A less laborious solution is to thoroughly hose off your plants — not just disrupt insects but also to clean off the leaves for better photosynthesis and cleaner, more attractive leaves
Organic Pesticides
At Cornell Farm, we have a strong commitment to environmental sustainability. In our own greenhouses, we use the Integrated Pest Management (IPM) model. This begins with checking our plants daily and eliminating pests by hand. When more substantive measures are needed, we use exclusively organic and non-systemic pest control. These are the same type of products that we sell to gardeners to help take care of their pest problems — and, most of the time, these gentler solutions are all you need to keep unwanted pests in check.
Horticultural oil and insecticidal soap are two of the most effective tools in your arsenal for organic pest control. Both will immediately clean bugs off your plants without lasting environmental residues.
Another low-impact option is biological controls — substances like spinosad, Burkholderia bacterium, or Bacillus thuringiensis (Bt). These are mainly derived from soil bacteriums that act as natural pathogens to insects.
For longer-term pest control, Bonide's Systematic Granules are mixed in with the soil and end up absorbing into the plants tissues for up to 8 weeks of protection. When a biting or sucking insect nibbles on the plant, they will be exposed to the imidacloprid. This can be useful for houseplants, which live in a closed environment where we don't want to see any insects. The flip side of systemic pesticides is that they can unintentionally impact beneficial insects — when a caterpillar chews on a leaf, they absorb the insecticide, too. If we want to see more of our beloved pollinators, we have to be mindful of pesticide usage and not choose a systemic product.
Pesticide usage can have major unintended impacts on our environment — just read our blog post about butterfly gardening to see the major impacts on our most charismatic organisms. Declines in butterfly and bee populations are a small window into what's going on with the rest of the ecosystem when over a billion pounds of pesticides are released each year.
Intense Measures
There are certainly situations where 'pests' need a strong response, like when invasive pests like the 'Murder Hornet' or Japanese Beetle need to be stopped before they spread everywhere. If you see harmful invasive insects like this in your garden, contact the Oregon Department of Agriculture for further advice. Harsh pesticides, including neonicotinoids, should be your last resort for trouble-shooting pest problems.
Preventing Pests
In the big picture, you probably want your garden to be a place where you, your plants, and nature can co-exist with minimal conflict. Instead of frantically applying pesticides, save yourself stress and heartache by aiming for long-term pest prevention strategies.
Right Plant, Right Place
Stressed plants are the most vulnerable to pest damage. A rhododendron that's thirsty and baking in the summer sun is much less resilient to hungry insects than a healthy plant that has the correct water, light, and soil conditions. When plants are stressed, they emit more infrared light — a powerful attractant for insects. Make sure your plants stay adequately hydrated to reduce heat stress and dehydration.
Since every plant has different needs, the most proactive way to set your plants up for success is to plant the right plant in the right place. Select full-sun, drought-tolerant plants for the brightest areas of your yard and look for shade lovers for areas that don't get much light.
Make space for bugs
Learning to co-exist with bugs — the 'good' and the 'bad' — doesn't mean letting aphids devour your entire garden. In fact, predatory insects and birds can start to balance these pests in a healthy ecosystem.
Companion Planting
Combining plants that offer each other ecological benefits is a strategy called companion planting. For example, chives, garlic, and other alliums can be interplanted with chili peppers and brassicas (broccoli, brussels sprouts, kale, etc.) to repel pests. Planting wildflower borders around food crops attracts predatory insects which make a feast out of unwanted pests. Companions can even act as shields to tender plants, acting as the first line of defense to attract hungry insects.
Leave It To Nature
There are profound benefits to leaving areas of your garden wild for nature to work. You may want your vegetables to be pest-free, but it's often okay to let insects munch on healthy perennials, trees, and shrubs. Separating these areas of your garden can help maintain your perfect produce while also creating the rich, balanced ecosystems that allow you to spend less time worrying about pests. Oak trees, for example, naturally play host to hundreds of species of insects — which is a tremendous thing for our wider ecosystem, both in and outside of the garden. A healthy oak tree can handle foraging caterpillars. Similarly, many of your garden plants will be fine with some insect activity. As long as bugs aren't causing severe infestations or long-term damage, consider going back to the '10 Step Program' — when you observe from afar, is the 'pest problem' really a problem or simply a sign that your garden is working as part of nature?
Unmanageable infestations of insects are often a product of an out-of-balance ecosystem. In addition to those companion plants, keeping perennials in the landscape offers habitat for beneficial predators like ladybugs, wasps, and beetles. One strategy to encourage snail-eating ground beetles is to maintain a 'beetle bump' — a raised mound of perennials and rich organic matter like mulch, providing a home to one of nature's best forms of pest control. Many birds rely on insects for food, so attracting birds to your garden is another way to collaborate with nature.
To Live With Bugs
We share our world with insects. Even though they can sometimes cause a major headache, most insects are harmless and even beneficial to our gardening goals. Insecticides can impact the entire web of life. As gardeners, we can be good stewards to nature and cultivate thriving gardens by working with insects rather than against them. In the spirit of Integrated Pest Management (IPM) and the 10 Step Program, we encourage you to take a step back and respond to pests by beginning with the gentlest possible response.
If you're dealing with a major pest problem and find yourself you're stuck on what to do next, our friendly and knowledgeable team at Cornell Farm is here to help. Visit us in-person or connect via email, phone, or social media to get your pest questions answered and get back on the right track towards a more balanced garden ecosystem.
For more resources on everything from identifying pest damage to safely treating nasty infestations, Oregon State University's Extension Service maintains an excellent database called Solve Pest Problems. We recommend OSU's resources because they're all drawn from high-quality scientific research that's regionally specific to Oregon and the Pacific Northwest.
