Category: Pests

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A Knotty Impatiens Problem

Orange Jewelweed – Impatiens Capensis by A. Walden

TheGardenLady received this question from Howard.

I have a North facing brownstone garden with partial sun here in Manhattan, New York City. Each year a good portion of the semi-shady part of the garden is planted with impatiens. They are the seedlings from the previous year so that I can enjoy them in the apartment during the cold months. When transplanted outside, the plants grow two to four feet tall and have volumes of flowers which produce large indefinite quantities of seedlings- continuing the cycle. I feed everything in the garden from my compost and that which I clean from the Koi Pond filter. At three AM the entire garden gets automatically rained upon daily for 15 minutes with sprinkler hoses wired to the top of all three fences. Recently this year (all I can describe them as) ‘Knots’ have formed on the tops of the plants. (I have a photograph to show upon your request.) It is the stunting of both leaves and buds. Lower leaves are browning. I, sadly, just cut all the plants back to about 18 inches and put the cuttings in the compost. At this time of year I usually have a mound of flowers so thick that the plants are barely seen. Now, I have a miniature forest of green sticks with few leaves. So far, I think nothing else is affected: potted house plants, ivy, basil, rosemary, lemon balm, Japanese maples, and the usual shade plant varieties. Please, tell me what the knots are if you can, how to prevent them from coming back, or what to plant next year in their place if I must. I will be most appreciative for your help as will all my neighbors who look down into my garden.

Impatiens are such bright cheery flowers that seem to have so few problems, I can understand how disappointed you must be to have unhealthy plants. This GardenLady plants impatiens around my front lawn to brighten the shady areas – this year I planted 200 impatiens plants, alternating white and red impatiens. I know how I love my impatiens as you and your neighbors appreciate your impatiens-filled back yard. So to make sure that I gave you the best, most up to date answer, I contacted the person whom I think of as the Guru of Impatiens, Derick Pitman.

Derick Pitman, known as Mr. Impatiens, lives in Sacramento, California, where he has been collecting and studying Impatiens for nearly 20 years and has been amassing scientific and horticultural information on this one plant. He was the founder of the, sadly now defunct, International Impatiens Society. He works with the Strybing Botanical Gardens in San Francisco (see here) with Impatiens species and has given many Impatiens species to Kartuz’s Greenhouses and Annie’s Annuals so people can buy these species to grow in their gardens. Derick Pitman loves to “talk Impatiens” with anyone who is interested. Derick has his own Impatiens website where you can contact him about your serious Impatiens problems.

Here is Derick’s response to your problem:

“My guess would be that the problem are mites, more likely Cyclamen mites. These mites are almost impossible to see but they like tips of new growth. I would trim off the tips and start a pest control program. You can use any solution for mites but stay away from oil based sprays; Impatiens don’t respond well to oil sprays. It could have been the heat that caused the mites to take off since they really multiply in hot climates. “


Adult cyclamen mites with eggs Image source: Manitoba Agriculture and Food

Another site with suggestions of Impatiens problems and treatment is this.

Howard, you offered to send a photograph of the ” knots.”  TheGardenLady would love to have your photo or photos to post on TheGardenLady.org. Please send the photo/s of the problem Impatiens plants so that we could all see what the knots look. We would also like you to send a follow up on your treatment and success rate.

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Pest Problems Related to Indoor Plants

Mealy bugs by mpshadow2003

TheGardenLady received this question from Ben about pests problems with indoor planting.

I know you have answered a few questions on dormitory planting before, and I have settled on starting with an Aspidistra and branching out once I’m comfortable with what seems to be a relatively easygoing plant. I’m simply looking to spruce up my room aside from the obvious posters and lights, so a plant and a small fish tank are on my to-do list this summer.

However, no one seems to address any kinds of pest problems related to indoor planting. Are there any major bug issues I should watch out for when dealing with dorm room plants? I have a room to myself as a Resident Advisor next year, so a south-facing window sill will be available year-round in Midwest temperate weather.

I like to keep the window open during the day so stagnant air should not be a problem, but I worry that circulation will increase the risk of infection either to or from the plant(s).

If I have missed anything or made some kind of gross assumption, your input would be much appreciated. Thanks!

You want to be prepared. Though you are correct to be concerned about raising plants indoors, most people have plants indoors and get away without serious problems. Raising plants indoors would not be such a popular hobby if there were that much to worry about.

Since all living organisms can have problems, I hope you are aware that fish can have health problems in their tank.  I remember how sad we were when our fish developed a disease known by its abbreviated name, ich.  We knew something was wrong in our first aquarium when we saw all those white spots on the fish. But raising fish is still popular and fun. You just have to be vigilant to see that everything in the tank is healthy.

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The Importance of Pest Control in the Greenhouse

Spider mites by theGardenDeva

TheGardenLady has invited people with horticultural interests and expertise to contribute posts to this blog.  The following post  about the importance of pest control in the greenhouse was submitted by Ahmet Korkmaz.

In the last decade the field of agriculture has undergone many important changes and improvements. People from all over the world are interested in implementing the new ideas that are being advanced by researchers in this developing field.

Greenhouse plantation is one of the exciting advancements that that has been adopted by farmers from all over the world.  Some of the the fruits and vegetables that are commonly planted in a greenhouse include cherries, drupes, radishes, cabbages, and tomatoes. These fruits and vegetables require unique ambient conditions, which a greenhouse can facilitate.

In a greenhouse,  sunlight is amplified for the plants because it gets trapped under a glass cover with four walls, which shield the plants from the heat that is generated. This extra sunlight and controlled heat promotes plant metabolism and provides nice returns in the form of vegetables and plants.

There are other advantages of growing of plants in a greenhouse. The leaves and other shoot parts of the plant can be protected from different kinds of chemical attacks that are air-borne.  Also, many pests and insects can be avoided to some extent in a greenhouse.  But a greenhouse does not prevent all pests.

Common pests in a greenhouse

Spider mites (see photo above), weevils, white flies, aphids and leaf miners are common pests in a greenhouse, the most common of which are the spider mites. Weevils cause a lot of damage to the surface of leaves. White flies tend to attack the major part of root and shoot systems. Aphids can be deadly to the green parts of a plant by feeding on a pigment called chlorophyll. This drastically affects the plant’s overall metabolism.  Leaf miners cause damage in tomato plantation. These pests tend to bore into the leaf’s vegetative part, which renders the leaf unable to take advantage of sunlight.

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Eliminating Pests in an Organic Garden

The Pill Bug by dragonseye
The Pill Bug by dragonseye

TheGardenLady received the following question.

I liked your site very much and would like to ask you what do I need to do to eliminate pests in an organic garden? I dont want to use any chemicals since the whole point is to eat what we grow and stay healthy. Do you have any good ideas?

TheGardenLady is pleased to know when readers enjoy the site.

What to do to eliminate pests in an organic garden is an excellent question. The answer is not short because there are many good ideas for keeping organic gardens pest free. Since fall is here, I will begin this answer now but will continue answering your question during the gardening year.

The first thing one should do in the fall is to get your gardens ready for the spring planting. Insects hide and breed in old, sick and dead plant material. So now is the time to clean your garden. Cut back leaves of perennials. After a heavy frost, remove all blackened plants such as zinnias, petunias, marigolds, etc.

Be absolutely sure that you clean diseased material from your garden. Remove and destroy plant stems on any perennials which may have had diseased foliage. Peonies, lilies, roses are some examples of plants that get diseases. Never compost any diseased material. THROW IT OUT! Good sanitation now will result in fewer problems next spring.

It is best to get rid of all the old dead plant material in the fall making it easier to start gardening in the Spring. But to pull out all the dead plants or not to pull out all the dead plants- that is the question. Insects will overwinter in dead plants- good insects as well as bad insects and birds and other wildlife will enjoy some of the plant material. If you are planning a vegetable garden in a certain location, TheGardenLady recommends cleaning out all the dead vegetable plants. However, if you leave some dead Native plants that offer berries and seeds in your flower beds, you might encourage some good insects to overwinter and help feed birds and wildlife in the winter.

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Whiteflies are Annoying Plant Pests

whitey the whitefly =) by ProDigi
whitey the whitefly =) by ProDigi

In the last post, TheGardenLady explained one reason why this time of year makes her sad.  Here’s another reason, the fear of bringing in plant pests.

Whitefly is of special concern.  See here.  Whitefly can get on your plants when they are outdoors. But it is a major problem of greenhouses or homes. One of the plants that I bring in for the winter is my Brugmansia or angel trumpet. This is a plant that  is prone to whitefly. Friends have thrown out their Brugmansia plants because of the infestation of whitefly on them. Sometimes one has to get rid of plants when the infestation is extremely large but there is no room to properly care for the plant. My house is not very large and some of these plants have become enormous trees which I can’t really spray indoors should they have an infestation. Or you might have to get rid of a pest ridden plant if you fear the infestation will spread to other plants. This is also a fear I have with two dozen other plants in my relatively small place. I have been lucky. In all the years that I have had plants indoors and in the three years I have been bringing my Brugmansia indoors, my plants have never had any pests.

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