This post was contributed by a community member. The views expressed here are the author's own.

Community Corner

Nature Scene: Fighting the Blight of Diseased Plants

A disease can significantly impact your home garden.

Gardening is one of the (few) things in my life with which I am fastidious. Oh, I’m creative with my plants’ colors, leaf shapes and textures, and the contour of the garden, both vertically and horizontally. I do try my best to pay attention to detail and work hard to keep things looking beautiful and interesting. (Too bad my office reflects my alter ego.)

We’ve been in this house about 25 years now, but it was only three years ago that my wife caught a bit of the gardening bug (thank goodness). It started when I was running behind with my May plantings due to business. No complaints about that, but the abundance of appointments was cutting into my being able to prepare the extensive beds and plant…significantly, and I was running far behind.

The problem was that I generally plant about 800 annuals every year. (No, that’s NOT a typo. And in the past two years, we’ve put in about 1,000 annuals. Gorgeous masses of color!) Everyone asks why I don’t just use perennials. I DO…and a good number of them are all around the house. But if you really, really love color, you need to work with annuals. Perennials are lovely, but only for a relatively short period of time. Various composite flowers, usually in the daisy family, can produce prodigious blossoms, but for only a few weeks, and then it’s all foliage. While some may re-flower, the second set is rarely as dense as the first. So if you want masses of color, plant annuals…lots of them. 

Find out what's happening in East Brunswickwith free, real-time updates from Patch.

I generally have a great time selecting plants from half a dozen very reliable nurseries (like a kid in a candy store. “Please, sir, may I have some more plants?”). Some garden centers always have my old standbys (like those gorgeous coral impatiens), but for some plants, I have to look around. Eventually, I can fill the areas around the house. The front is either mostly sunny to only part sun. The driveway is partly sunny, and the backyard is mostly dappled sun to heavy shade. We ring the property with large plantings of impatiens (mostly), both single impatiens (about 700) and dozens of double impatiens (very lovely, like little roses).

Several years ago, we found “exotic impatiens.” These originated in warm regions and run into true oranges and yellows. Yes, yellow impatiens. They don’t flower in quite the same way as standard impatiens, but they are a really beautiful accent in places you would like something that is NOT in the red, white, pink and purple family. Of course, there are other annuals as well, including New Guinea impatiens. These are different from standard impatiens and provide a nice contrast in shape and texture. They also tolerate shade well.

Find out what's happening in East Brunswickwith free, real-time updates from Patch.

(I should mention that regular impatiens CAN tolerate sun well. They may droop a bit during the heat of day, but as soon as the sun is off of them they perk up again. Seems the sun causes transpiration faster than they can absorb moisture.)

Other annuals might include hibiscus and mandevilla for larger pots. These plants may be perennial in the south, but not here. But their color is wonderfully lush and a reminder of the tropics. There are lots of additional annuals, including lycopodium, pansies, salvia, geraniums, marigolds, caladiums, a new form of non-stop begonia (fabulous), and more. This has always been a show-stopper of a garden. 

OK, what’s the trouble? This year, for the first time, we’ve been hit with a blight that has taken out at least 150 impatiens (so far). It happens quickly, and it’s always fatal to the plant. For a day or so, they will appear droopy, even though the soil may be sufficiently moist (and not necessarily overly wet). The next day, the stems will all have collapsed at the soil line, as if they were dropped into a large pot in a circular pattern, like pick-up sticks or spaghetti. The stems have rotted at the soil line, and the plants are essentially dead at that point. Neither watering or feeding practices have changed. Plants, soil amendments and mulch are all obtained from the same reliable sources as in past years. This IS a mystery!

I have been reading and reading and reading some more. There are two prominent ideas that may explain this condition, but not really a lot of information about it. My observations indicate this problem can occur with plants that are in fairly dry soil, or those in generally damp soil. It happens whether mulch is up against the stems or not. It can occur with masses of plants or a single plant. There is no single locational or situational cause that I can pin down. I did notice, however, that several plants, from different suppliers, had one or two specimens in the flats of 36 or 48 that appeared this way. So, as with the tomato blight that was transmitted throughout the East Coast last year through the big-box suppliers, something is present in this year’s purchased impatiens that may be causing this. It may well have come in from outside. 

A very good friend, who is extremely well trained and knowledgeable about most things having to do with plants, researched possible causes and came up with what he considered a likely cause: a fungus. It matched many characteristics he found, and he suggested using a fungicide. I did try one, and it may have helped a bit, but not completely. Hard to tell, but the mass die-off may have abated. 

Several internet sites suggest a bacterial cause, which also matches some of the symptoms. Our planting impatiens in the same beds for many years in succession may have contributed to this condition. No remedy was offered for this, and there was no suggestion as to whether the bacteria would diminish after the winter or in successive years. The same site (gardening.yardner.com) also suggested a possible fungus. Here is the text about those two conditions:

Plants Wilting Suddenly, Stems Rotting at the Soil Line Signals Bacterial Wilt.

A disease caused by a bacteria causes sudden wilting and collapse of impatiens plants. Yellowish masses of bacteria ooze out when the stems are cut. Stems are often rotted at ground level. Remove and discard in the trash severely infected plants and garden debris. Disinfect any tools by dipping them in a solution of hot water and household bleach or spritz them with household disinfectant spray. Avoid planting potatoes, tomatoes or eggplants nearby which are vulnerable to this same disease. 

Plants Stunted, Yellowed or Brown Spots on Leaves Means Fungal Disease.

Fungal diseases sometimes attack impatiens. A wilt disease works its way up from the base of the plant, causing leaves and branches to wilt and die. A leaf spot disease causes circular brown spots on the leaves. Stem rots attack impatiens stems at or near the soil level. Foliage turns yellow, wilts, and dies. 

There is no practical treatment for these problems in inexpensive annual plants which die at the end of the season anyway. The best strategy is to promptly remove and discard badly infected plants with their soil in the trash to prevent the spread of the fungus to other plants. Do not grow impatiens continuously in the same location every year. Control weeds in and around the yard. Sterilize tools after use on infected plants with a spritz of household disinfectant spray or dip them in a solution of hot water and household bleach.

Mulching helps prevent splash-borne infection in outdoor plantings. For long term prevention, lighten heavy soil with a mixture of perlite, vermiculite or peat moss and provide good drainage. Avoid over-watering. Space plants further apart to prevent crowding.
Click here for more information on Dealing with Fungal Disease

And from hiortchat.com:

Sharon

August 20th, 2010 at 1:12 pm · Reply

Stem rot
I planted impatiens in a new bed this year and I am having trouble with some of them rotting at the base of the stem and the whole stem is dead within a day or so this has wiped out at least half of my plants. The impatiens that I have left are beautiful and healthy looking is there anything I can do to stop this fungus or whatever it is from destroying the rest of my plants.

Hi Sharon
It sounds as if your impatiens have a stem rot which will cause the plant to rot and fall over. Cut one of the infected stems and check for a yellowish ooze which will indicate a bacterial wilt disease.(Pseudomonas solanacearum). If the plants turn yellow, wilt and die, then it may be a fungal stem rot. Either way, to control stem rot, avoid over-watering and crowding of plants. Keep mulch away from the base of the plant.
Sanitation is important: remove any diseased plants and debris. If you cut away infected parts be sure to sterilize the tools in 70% alcohol or 1 part bleach to 3 parts of water. Do not compost diseased parts. If you think the stem rot is caused by a fungus, you can spray the healthy plants with a fungicide to help control the disease and keep it from spreading further.
For next season, make sure your impatiens are planted in well drained soil, you may have to amend the soil to improve drainage.

Here is a piece from the Baltimore Sun that deals with the same issue. 

Allexperts.com made this suggestion, and it may be worth trying:

You could also try spraying the plants and soil with Serenade (Bacillus subtillus) which is  a "good guy" bacteria that out competes the bad guy fungi - spray stems and soil in the AM = and alter the watering so that the surface of the soil around the plants drys out in between waterings.

I wish to point out that (to date) none of the double impatiens, coral-colored double impatien flower exotic impatiens or new guinea impatiens appears to have been coral and yellow exotic impatien flower affected. It makes me wonder if the extremely fleshy stems of Red new guinea impatien flowers are particularly susceptible to this condition. 

So what’s the solution? After all this reading, I still don’t really know. We’ve been losing plants at a fairly rapid pace, but it may have slackened now. We’ll have to see if all the impatiens succumb to this blight or if it seems to diminish throughout the summer.

As for next year, if we believe that we can try some impatiens again, we’ll add some sand to the soil to break up the heavier clay we have, and we’ll improve drainage, will keep plants further apart, will not use mulch around impatiens, and will watch the watering more carefully to prevent continuously soggy soil.

On the other hand, I suppose we also may try other types of plants to fill in for the reduction in color we will suffer if we don’t plant the regular impatiens, or many fewer of them. Perhaps we may use many more polka-dot plants (red, pink and white ones), those lovely begonias that we first found this spring, and anything else that might provide mounds of color for shade or semi-shade. The most positive thing I can say at this point is that I will keep you posted. 

Here’s hoping that no one else is afflicted with this problem. Enjoy your gardens and flowers. They are the treasures you created. 

Thanks,

Rich

This column also appears regularly in Mr. Wolfert's blog, Nature Notes...a Lifelong Journey.

We’ve removed the ability to reply as we work to make improvements. Learn more here

The views expressed in this post are the author's own. Want to post on Patch?