Sulfur
A Great Ally of the Rose
By Carol Green
For those who grow roses, few materials we use can boast of as many benefits as the element, sulfur.
Sulfur is available to rosarians as a major ally in our efforts to produce beautiful rose blooms and bushes. No
other component is found in as many varied applications and uses. Sulfur is used by rosarians as an
insecticide, a miticide, a fungicide, a fertilizer, and as a soil amendment.
Some Things You
Know About Sulfur
and a Few You May
Not.
On the periodic table of elements, sulfur is identified by the symbol S.
The element has an atomic number of 16. Sulfur is a mineral, and in
its natural state appears in a golden yellow colored crystalline form. It
is spelled sulphur in many Countries. The sulfur spelling was adopted
by the International Union of Pure and Applied Chemistry, IUPAC,
(the world authority on chemical nomenclature) in 1990.
The term “brimstone”, included in the Biblical phrase “fire and
brimstone”, is believed to refer to burning sulfur. In fact, in the
Bible,“Hell” is said to have the smell of sulfur. Scholars believe this may be due to its association with
volcanoes. Historically, sulfur has been used for over 4,000 years for a variety of purposes including, but not
limited to, medicine, bleaching, insecticides, resins and as a fumigant to “chase the devil away”.
With the birth of chemistry, around the 1700’s, the use of sulfur in industry is said to be the single most
important development leading to the Industrial Revolution. More sulfuric acid is produced in the US every year
than any other inorganic industrial chemical. Sulfur, in its elemental and oxidized forms, represents 1.9% of the
earth’s total weight. Pretty impressive!
From the late 1700’s to the late 1800’s, almost all sulfur came
from Sicily. However, with the onset of the Industrial Revolution,
the demand for this mineral became so great that other sources
were needed. Around 1867, large underground supplies of
elemental sulfur were found in Texas and Louisiana. Today the
US leads the world in sulfur production, followed by Canada,
Japan, France, Poland and Mexico. There are also other sulfur
deposits around the world, often located near volcanoes.
Although we are
primarily interested in
the way sulfur benefits
our roses, the many other
ways it benefits society
are overwhelming.
Well known by some, but little know by others, the Chinese
developed gunpowder in the 1300‘s by mixing sulfur with other
substances. Sulfur is also used in making matches, rayon,
cellophane, vulcanized rubber (for tires) and impregnating wood
and paper products. Sulfur compounds are used in detergents, dyes and even in some acne treatments.
A secondary source of sulfur is sulfur dioxide, which results from industrial wastes and flue gasses. Hydrogen
sulfide is found in “sour” natural gas, coke oven gasses, and petroleum refinery products. In the past, these
gasses produced “acid rain” which lowers the pH in the soil and in fresh water bodies. It also causes, in part,
the chemical weathering we see on statues and outdoor structures.
Fuel standards in recent years have increasingly required that the
sulfur be extracted from fossil fuels. It is then refined and is added to
sulfur production. What was once considered a negative has now
become an added benefit.
Natural sulfur crystal
Industries using sulfur as a primary ingredient are Animal Feed,
Explosives, Fertilizer, Petroleum Refining, Steel, Sugar Refining,
Pesticide Manufacture, Matches, Poultry, Inorganic Chemicals and
Organic Chemicals. The equivalent of 120 pounds of sulfur per
person are used every year in the manufacture of over 30,000
items. With the advent of the Industrial Revolution and the
availability of sulfur in the form of sulfuric acid, it has become one of
the basic materials of industrial production.
For many of us, the first thing that comes to
mind when sulfur is mentioned is the smell.
Rotten eggs! Most of us have sprayed lime
sulfur following our spring pruning, and it is a
very unpleasant product. Hydrogen sulfide,
an odor produced by bacteria, is responsible
for the smell of decomposing products, untreated sewage and some intestinal gasses. Sulfur dioxide is the
smell associated with burnt matches, and is caused by burning sulfur. And finally, the odor of skunk spray is
made up of sulfurous compounds.
Oh......That Awful Smell!
However, sulfur is also responsible for some of our most pleasant flavors, although some may disagree. The
primary source for the flavor in broccoli and onions comes from…….. sulfur.
Now we get to the many ways sulfur can benefit roses!
The EPA (Environmental Protection Agency) has a way of ruining our days and
getting in the way at times. It often sends out warnings that scare us away
from products, usually with good cause. However, when it comes to sulfur, it is
as if this product can do no wrong.
Sulfur is registered with the EPA as an insecticide, fungicide, for use as a
fertilizer and soil amendment. It is the active ingredient in nearly 300 products.
It has been registered as a pesticide since the 1920’s. According to the EPA,
sulfur is known to be of low toxicity and poses very little risk, if any, to human
health. The EPA goes so far as to state in its Sulfur R.E.D.Fact Sheet the
following: The use of elemental sulfur as a pesticide or a soil amendment is not
an environmental concern because it becomes incorporated into the natural
sulfur cycle. It is not detrimental to birds, bees, fish or any non-targeted
species. It is not carcinogenic. It doesn’t mutate, but returns to a natural state
in the environment. Very few products available to rose growers can give us as
much confidence in our safety and still have limited environmental impact.
Sulfur as a Fertilizer
It is said that the
indication of a
country’s level of
industrial
development can
be linked to its
consumption of
sulfur.
Sulfur is a key element in plant growth. It is vital to the production
of vitamins, amino acids (proteins) and enzymes. A sulfur
deficiency looks similar to a nitrogen deficiency. There are
generally two forms of sulfur that are used as fertilizer. They are
Elemental sulfur and Sulfate sulfur.
Elemental sulfur depends on time, temperature and moisture to become available to plants. It is used to
acidify the soil. This is the sulfur that is added if we are trying to lower the pH of our soil. Over time, the sulfur
is oxidized by microorganisms to form sulfuric acid. Sulfuric acid supplies the sulfate ion, which is taken up
by plants.
Sulfate sulfur is available to the plant immediately but will not acidify the soil. This is the sulfur that is found
in the most common sulfur-containing fertilizers we use. Fertilizers, such as Sul-Po-Mag or K-Mag,
magnesium sulfate, and gypsum (calcium sulfate), contain around 20% sulfur.
We may not realize that time-release fertilizers are yet another way we benefit from sulfur. In the 1960s and
1970s, sulfur was chosen as the principal coating material for the newly developed time-release fertilizers.
This was because of its low cost and value as a secondary nutrient. Often, other coatings or sealants are
added. However, as rosarians, we owe much to the advent of this form of fertilizer. Its success is due in large
part to the role played by sulfur.
Sulfur as an
Insecticide and
Miticide
Lime Sulfur is produced by boiling lime and sulfur together. This
results in a dormant spray that many of us use every spring after we
prune our roses. It is said to control over-wintering diseases and
scale insects in our Florida gardens. It is one of those products we
would rather not use, but fear the potential bad results if we don’t.
The most common use of sulfur for insects and mites is in the form of
a dust. However, care must be taken when applications of sulfur
products are made in temperatures above 90 °, or burn damage may
occur. There have also been significant strides in the production of
flowable sulfur products, which are easier to apply.
Sulfur as a Fungicide
The use of sulfur as a fungicide is of paramount
importance to those who strive to maintain rose
foliage free of fungal blemishes. Few of us can say
that we have never used sulfur in our battle against
fungal pests. And, even if you don’t think you
have………….you probably have!
As a fungicide, sulfur is labeled as a non-systemic contact protectant. Sulfur is used either as a primary
ingredient or as a secondary ingredient in so many fungicides that this writer had difficulty isolating its
presence in many products. Nevertheless….it was there over, and over. Some well-recognizable products
include Mancozeb, Dithane, Manzate, Zyban, Bonide and Kocide.
Research indicates that virtually all copper based fungicides include a sulfur component, although you may
not find it listed on the manufacturer’s label. For example, Kocide lists as its active ingredient, copper
hydroxide. Copper hydroxide is produced by combining sodium hydroxide with copper sulfate. Copper
sulfate is produced by combining copper compounds with sulfuric acid. Sulfuric acid is produced by
combining sulfur, oxygen and water.
Mancozeb is an ingredient used in many of our favored fungicides. Mancozeb is a dithiocarbamate.
Dithiocarbamates are a group in organic chemistry. They carry sulfur atoms instead of oxygen atoms. This is
a vast oversimplification, but demonstrates the role once again played by sulfur.
In addition to these important uses as a secondary element in disease control, sulfur is prominent in its own
right as a dust or flowable product in controlling powdery mildew, blackspot, rots and other fungal diseases.
Lime sulfur is again significant in its use as a treatment for powdery mildew fungi.
Look for the Sul...............
Sulfides, sulfites, sulfate, disulfide, sulfurous, thiosulfurs, polysulfides and the list goes on and on.
Sulfur exists in every part of our everyday lives and is especially important to each of us as we tend to our
roses. If you see “sul” as a prefix or suffix, then sulfur has played some role in the product you are using.
Several years ago, as a new rosarian, I recall reading somewhere that “we should never overlook the
importance of sulfur to roses.” I wish I had recorded where I read the statement. It has haunted me until writing
this article. Now I have a greater understanding and appreciation of this mineral. With regard to that statement
from some 10 years ago................I couldn’t agree more.
No rose related article would be complete without the inclusion of a rose. As expected, we are pleased to
provide information on none other than.........the Sulfur Rose, so named because of its reported unpleasant
scent.
Sulfur Rose
R. hemisphaerica
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Picture source: Les Roses, Volume I (1817)
Original Botanical Name: Rosa Sulfurea
Original French Name: Rosier jaune de souffre
Current Botanical Name: R. hemisphaerica
Common Name: Sulfur Rose
Other Names: Double Yellow, Double Yellow
Provins, Yellow Centifolia
Class: Wild Rose
Origin: Turkey, introduced to Europe prior 1625
Flowering: Once-flowering; summer
Scent: Slight – some say unpleasant
Growth: Tall shrub; 6 feet tall (1.8 metres)
Availability: In cultivation
At left, the Sulphur Rose; R. hemisphaerica, painted
by Redouté, portrait 004 out of 170, Volume I of Les
Roses.