Hey, Sherlock, come take a look at my houseplants

By Lynette L. Walther | Nov 19, 2012
Photo by: Lynette L. Walther Tender plants, such as these orchids, need cold protection indoors. Occasionally unwanted pests come in along with their host plants.

Opportunistic, sneaky little parasites — no, I am not referring to your in-laws but rather those insect pests and diseases that hitchhike indoors with potted plants that vacationed outdoors during the summer. However, oddly much like those in-laws there’s a scourge of the creeps, and many of them look a lot alike. This time of year they can darken your doorstep at the drop of a hat.

It did not take long, but within a few days of bringing my orchids indoors when cooler weather showed up I noticed little shiny brown bumps on the undersides of several of the leaves.

On closer inspection my worst fears were confirmed (cue the “Law & Order” kladlung here) — scale! Not a disease, but an insect pest, scale can wreak havoc with an orchid (or any other plant for that matter) if ignored. Obviously this infestation occurred sometime before the plants were moved inside, scale being one of those things encountered outdoors. Unfortunately scale is just the tip of the iceberg when it comes to the rabble of unsavory associates that indoor plants can consort with when placed outside for the sun and pleasant weather. And bringing them indoors for the winter only allows those creepy crawlies to flourish.

Examine the pots themselves, as well as the plant’s foliage (top and bottom of the leaves) and the soil surface when preparing to move potted plants inside. Run the tip of your finger along the bottom edge of the rim of the pot, a common place for insect eggs or pests to hide. Better yet, take a clean cloth rinsed in a weak bleach solution and wipe the entire outside of the pot. If pests are detected, quarantine infected plants and treat them before moving plants indoors.

"What’s Wrong With My Plant? And How Do I Fix It?"

By David Deardorff and Kathryn Wadsworth

Timber Press, Portland/London

Paper: $24.95 Pages: 451

Let’s say the leaves on your peach tree are distorted and have turned red and purple. Or maybe there are these little brown bumps on the undersides of the leaves on your philodendron? Or you notice whole branches of the juniper have turned brown. Looks like trouble on the horizon, but what exactly is going on here?

To be sure it probably isn’t something good, but diagnosing these and other plant issues is now easier with a new book, “What’s Wrong With My Plant? And How Do I Fix It?“ by David Deardorff and Kathyrn Wadsworth. It’s all easily found in this book, enabling you to discover and cure issues in flowers, herbs, fruits, vegetables, bulbs, houseplants, seeds and seedlings, shrubs, trees and lawns.

“Most resources on plant problems are difficult to use,” begins this innovative reference book. “Almost all require you to know the name of your plant before you can proceed. This book is different. It presents a diagnostic system with easy-to-use flow charts. By observing symptoms on your plant…you can follow the flow charts to a diagnosis.”

"What’s Wrong With My Plant? And How Do I Fix It?" is bound to be one of the most-used, most-referred-to books in your garden library, and unlike many previous books of this type, this volume is easy to navigate and is bound to be your go-to source for organic solutions for a wide variety of plant issues.

Here’s what it contains:

• Part I has easily understood charts which take you through the symptoms to enable you to accurately diagnose your plant’s problem. • Part II explains the cure, whether it is one involving pests, disease or growing conditions.

• Part III contains a photo gallery of all common problems. It doesn’t get much easier than this, enabling you to deal with all manner of plant problems. If there is one book you are planning to add to your gardening library, this should be the one, one that will pay for itself and make your job in the garden a whole lot easier and more successful.

In the event that your precautions fail and pests (or plant pathogens) make it inside along with your potted plants — fear not. There are often simple solutions, with early detection and prompt action being your best chances of getting things under control with minimal damage to the plant(s). Dennis Milliken of Green Thumb Nursery spoke on the subject of houseplant pests at one of Merryspring Nature Center’s Tuesday Talks, and outlined the usual suspects:

• Aphids — These tiny insects multiply quickly. Wash them off plants with a steady stream of water, or spray with neem oil, horticultural soap or horticultural oil.

• Mealy bugs — Insects form colonies that suck juices from the plants and are commonly found on hibiscus. Use horticultural oil or a soap spray.

• White flies — The tiny flies can damage foliage, spread disease. To control, use horticultural oil soap spray or a sticky yellow card.

• Scale — Small, shiny brown “bumps” often on undersides of leaves. Scale sucks the juices from the leaves. Remove with a swipe of a soft cloth or spray with a neem solution or horticultural oil once a week for eight weeks.

• Spider mites — Tiny insects, spider mites damage foliage and can be controlled by a direct spray of water, a neem oil or horticultural oil spray.

• Thrips — These insects carry plant diseases and scrape leaf surfaces. Control with a horticultural oil or soap spray or a neem oil spray.

• Leaf miner — Tiny burrowing insects create “tunnels” within foliage. To control, remove infected leaves or use a neem oil spray.

• Fungus gnat — The larvae of this gnat feeds on the plant’s roots. Put a slice of potato on the surface of the soil. It will attract the larvae and can then be discarded.

• Downy mildew — Often impacting impatiens, this fungus can live in soil for three to five years. Difficult to control, copper fungicide spray is helpful, or discard plants and soil.

• Powdery mildew — White, fuzzy clusters. Use a spray of sulfur or neem oil.

• Alternaria — Black spots on leaves with yellow halos indicate this fungus. Control with a spray of Fungonil.

• Tospovirus — White, yellow or tan-ringed spots of this virus are difficult to control. Discard plant and soil.

• Bacterial leaf spot — Sunken dark spots with yellow halos. Use a diluted solution of Lysol.

• Anthracnose — Brown-tipped leaves often indicate this bacterial infection. Discard plant and soil.

• Bacterial wilt — Leaves turn pale and then brown. Discard plant and soil.

• Oedema — This condition, not a disease, manifests itself in wart-like corky swellings resulting from over-watering.

• Botrytis — Brown spots on foliage, often of geraniums, can be controlled with improved growing conditions providing air movement or Fungonil.

Yes, there are plenty of potential problems, and yes, I’m sure you’ve noticed that often their symptoms are disturbingly similar. Here’s a link to a University of Maine site that will lead you to photos of many of these houseplant pests/problems: maine.gov/agriculture/pesticides/gotpests/index.html. There are other websites and books, like the new “What’s Wrong With My Plant? And How Do I Fix It?” (see sidebar) for more images and information on plant problems.

I know this looks as if we are outnumbered by insects. We are, but don’t be discouraged. These are often worse-case scenarios. The first line of defense is maintaining houseplant health along with a bit of detective work on the plants and their pots on a regular basis. As always, healthy plants are more resistant to insect and disease skullduggery. Happy hunting.

Lynette L. Walther is the recipient of the Garden Writers Association’s Silver Award of Achievement for 2012, and she gardens in Camden. Got questions, or comments? Visit her blog, and join in the conversation at: gardeningonthego.wordpress.com or join her on Facebook.

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