Deicing Salts

The Home & Garden Education Center has received an abundance of inquiries related to Japanese pachysandra, (Pachysandra terminalis) during the last few weeks. Homeowners all over Connecticut are experiencing difficulty with this groundcover. It first becomes noticeable as other things around it start to green up in the spring and we see that the leaves are remaining a sickly shade of yellowish-green.

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Affected bed of pachysandra

As it catches our attention we notice that the plantings in general look a bit sad and sparse. A closer look at the leaves will reveal that there are areas of irregular brown blotches that have concentric line patterns within the affected area and pretty sharply defined darker brown edges. The center of the spots will can appear much lighter if the salmon-pink fungal spores are present.

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Pachysandra leaves showing signs of Volutella blight

The browning areas will continue to spread and darken and can encompass the entire leaf as it dies. The cankers that can develop on the stems and stolons can girdle the stem and cause the plant to wither and die by disrupting the transport of water and minerals through the plants vascular system.Unfortunately this can happen in as little as two weeks, especially if the weather is wet and humid. It has certainly been wet over the last week and although the total precipitation is around the average 1” needed for growing plants it has come in a slow but steady sprinkle allowing plants little time to dry out between the showers.

This is all the work of the fungus called Volutella pachysandricola, or Volutella Leaf and Stem Blight. This fungus is considered an opportunistic pathogen that attacks weak plants. It can infect leaves, stems, and stolons and is considered the most destructive disease of pachysandra. The pink spores that appear in the spring will darken to reddish-orange in the late summer and fall when a second type of spore is produced.


Close-ups of the Volutella damage and spores

This winter may have provided the perfect storm needed by Volutella to thrive. Drying winds and winter sun can desiccate pachysandra if there is not an adequate cover of snow to provide protection. Also, many beds of pachysandra are near roads and sidewalks where salts may dry them out further. A cover of mulch could provide just enough needed winter protection for plantings in these areas but it should be removed in the early spring. Some symptoms of winter injury or sunscald such as tan or scorched leaves may initially appear to be Volutella but they will not exhibit the characteristic concentric lines of the disease.


Those same pachysandra beds that are near sidewalks or roads or are used as edgings can receive damage from mowers, clippers and weed whackers (Or as they are called in Australia, ‘whipper snippers’. I just love that!). Cuts from lawn equipment can provide an opening in plant tissue and when the plant is wet the fungal spores are able to infect it easily and travel to the stems where they will cause the girdling mentioned earlier.

Good sanitation practices can be helpful when dealing with pachysandra blight. It is too late for a good fall cleanup now but you can still remove any plant debris that remains. During dry weather remove and bag (not compost) any diseased plants to reduce the inoculum. Thinning out beds will also help improve the air circulation that can speed up drying. Fungicides can be used as preventives for new growth or when wounds occur and systemic curatives can be used when symptoms first appear although they will not correct damaged tissues. Allegheny pachysandra (Pachysandra procumbens) can be less susceptible to the disease or you could consider another groundcover such as creeping myrtle or vinca.


Vinca major, also known as variegated greater periwinkle

Another source of wounds to pachysandra that should not be overlooked in insect damage. Scale insects such as Euonymous scale, two-spotted spider mites, and root knot nematodes have been found on plant samples that have come in to the Center. Horticultural oils and insecticidal soaps applied now can help control scale, just be sure to thoroughly coat the pests with the product. A miticide can be used on the spider mites but there is currently no control chemical treatment for the nematodes.

Euonymous scale

Euonymous scale image by Joan Allen

If you are experiencing these symptoms in your pachysandra beds you can get additional information from the Connecticut Agricultural Experiment Station fact sheet entitled Volutella Blight of Pachysandra, on our website at Pachysandra Leaf and Stem Blight, or by contacting us at the UConn Home & Garden Education Center.

-Susan Pelton








Ok I have had enough snow and ice for the winter. Although I say I am done, I know there is more to come, so lets learn to deal with it. That sheet of black ice on top of my driveway and sidewalk needs an ice melting product, but which one and what is the difference in the products I find in the local hardware store? The answer is in the chemical makeup and temperatures at which they are most effective.

There are five different deicing products readily available;  Sodium chloride (rock salt), calcium chloride, potassium chloride, magnesium chloride and calcium magnesium acetate. You may find these products packaged individually or two or more combined together to take advantage of their different ice and snow melting qualities.

Sodium chloride (rock salt) (NaCl) is the old standby. It is commonly available,  widely used for decades and inexpensive.  As sodium chloride dissolves, it releases the most amount of chloride ions causing the most damage to surfaces and plants. Chloride can corrode metal and seep into ground water, and streams and rivers causing pollution. It is most effective melting ice above 20° F. It will not work below 16° F.

Calcium chloride (Cacl2) will melt snow and ice at a much lower temperature, down to 25° F. It comes in different forms, white pellets, flakes and liquid.  Its down side is it can cause skin irritation if handled and is easily washed away from where it is used meaning you must reapply it more frequently than some of the others. It can also cause damage to concrete surfaces like sidewalks. It can damage plants if it is overused or concentrated in areas such as road sides and under  repeatedly added to snow piles.

Potassium chloride (KCl) works when the air temperature is above 15° F. It is commonly used as a fertilizer for plants but too much will burn plants. It will melt ice until the air temperatures reach 12° F.

Magnesium chloride (MgCl) is less damaging to concrete, plants and trees. It is the new kid on the block and may be referred to as ‘environmentally safe’.  It melts ice and snow down to -13° F. Magnesium chloride will not leave a white residue on shoes or floors and claims to be gentler on vegetation. It release 40% less ions than calcium chloride making it less toxic to the plant life and less harsh on concrete.

Calcium magnesium acetate (CMA) is made from dolomitic limestone and acetic acid. It is a new salt-free product. It is  effective to 25° F. It is most costly better easier on the environment and vegetation and concrete. CMA prevents ice particles from sticking to each other.

Always read and follow label directions when applying deicing materials.