Let’s Talk About Garden Pests (and Disease)

The space vacated by Phlox paniculata ‘John Fanick’. Photo by Kit Flynn.

HOW DOES YOUR GARDEN GROW

By Kit Flynn
Columnist

The sad truth about gardening is that you are sometimes forced to confront garden pests and diseases. This is definitely the unsexy side of gardening but one you must consider if you desire to have a successful garden. No matter how good a gardener you are, there will be that awful time when a pest or disease invasion swamps you.

Around ten years ago, aphids decided to assault my garden. A neighbor’s tree, in poor shape near the edge of my garden, was riddled with aphids. The aphids soon jumped ship, infecting one of my pines. Before I noticed it, the tree was black, so there was no choice but to take it down or spray the area with a toxic chemical. I chose the former. The sad truth about aphids is this: They are easy to demolish on plants with a quick dose of insecticidal soap but are difficult to exterminate when they decide to settle on trees that soar about eye level.

Many of our esteemed plants are susceptible to particular garden pests or garden diseases. Certain monarda and phlox are guaranteed to come down with powdery mildew. In fact, I have taken out two larger patches of Phlox paniculata ‘John Fanick’, planning to replace them with P. paniculata ‘Jeana’ – I simply grew tired of the arrival of the unsightly powdery mildew every August.

Therefore, I have concocted several garden rules that I try to follow:

Rule #1 is this: Select plants that are resistant to pests and disease, avoiding those that will succumb to them. I always choose roses that are listed as “disease resistant” – this doesn’t mean my roses won’t come down with black spot, a fungal disease that’s in our soil, but it does mean that there’s a good likelihood that the disease resistant rose bush will not die from it.

Use the Internet as there’s lots of good information on it (yes, you’ll have to wade through some bad information) by searching out those sites ending in .edu.

Rule #2: Design your landscape beds with diversity in mind. A long line of boxwoods can be risky as Boxwood Blight, a fungal disease, is now here in North America – and it can wipe out that line fairly quickly. Diverse planting helps to mitigate the destructive nature of many of our pests and diseases.

Rule #3: Become a really observant gardener and this applies to both indoor and outdoor plants. In my kitchen bay window, I grow a wide variety of Phalaenopsis, commonly known as moth orchids, that I tend to every Sunday morning. Suddenly, I noticed that almost all of them suffered from a large invasion of scale infiltration.

I was guilty on two points for this infection: (1) I should have inspected each and every new orchid that I introduced to my collection before giving it a home; and (2) I should have always closely examined all the orchids during the Sunday administration of care. Before introducing any plant to your home or garden, go over it with an inquisitive eye.

Do not assume that just because you bought a plant from a well-established nursery, it’s clear of pests or disease. Once I bought some cannas from a good nursery, only to have them break out quickly with Rust, a disease that I’d never encountered in my garden. I quickly removed the offending cannas as I certainly did not want it to spread.

This leads me to Rule #4: Remove the pest or the diseased leaves early. You have a better chance of saving that boxwood if the blight has only affected one branch. I could have saved my pine tree if I’d caught the aphid infestation earlier.

Rule #5: Site the plants to match their requirements. A sun-loving rose will not survive in a shady area. Plant a fern in a sunny site, and you’ll end up with a most unhappy fern. Ferns can cope with light, only they aren’t in direct sunlight for any length of time.

Know the needs of your plants needs–and your various gardening areas. Most plants – but not all – dislike being left in standing water as they want well-draining soil. Roses require a set amount of water on a weekly basis, while echinaceas can easily survive a temporary drought. All this is information you can find on the Internet, so don’t be afraid to research the plants you’re thinking of purchasing – and refrain from buying those that dislike our climate. It’s so easy to order inappropriate plants from a mail-order nursery. Lilacs grow well up North; they fail miserably here in the Piedmont.

Our local garden centers do not always sell appropriate plants, so be vigilant. I yearned to have Hakonechloa macra, a lovely ornamental grass, in my garden. After three attempts, I wisely refrained from planting it again, realizing I couldn’t give it the cooler growing conditions it requires.

Rule #6: Please know your pest before you spray. If you see a bug on your azalea, determine what kind of bug it is. Not all bugs are injurious to plants. I know gardeners who automatically reach for that bottle of Malathion or Sevin when perhaps all they need is a shot of insecticidal soap. It could even be a beneficial bug that should remain on the plant. Refrain from an overreaction.

Camellia sasanqua, one that required spraying. Photo by Kit Flynn.

Now this doesn’t mean that you shouldn’t ever resort to chemical warfare. I have many older camellias that provide me with a lovely evergreen backbone of my garden. They had a scale infestation – and scale can be difficult to control. Consequently, I now have them professionally sprayed simply because I am not willing to lose them without a fight. Did I make the right choice?  Organic gardeners would have said, “No!” However, while I employ organic practices whenever I can, I’m not so wedded to them that I’m willing to sacrifice my camellias. That’s my choice, one that you might disagree with.

And, as a gardener, remember some choices are like the ones you make in politics: The choice is up to you.


After being an active member of the Durham County Extension Master Gardeners for 13 years, Kit Flynn now holds emeritus status. For five years she was the gardening correspondent for “Senior Correspondent” and shared “The Absentee Gardener” column with fellow Master Gardener Lise Jenkins. She has given numerous presentations on various gardening topics to Triangle organizations and can be reached at howyourgardengrows@icloud.com.
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