Sulfur, element #16 on the periodic table is a plant macronutrient found in the Earth's crust at around 0.1%. Sulfur is most abundantly found in sedimentary deposits and is less abundant in volcanic rocks. Roughly 95% of available Sulfur in soils is in the form of sulfate esters and carbon-bonded Sulfur
Let's take a quick look at the main uses of Sulfur by plants.
- Involved directly in photosynthesis.
- Essential in the activation of many key enzymes.
- Crucial in the formation of proteins and amino acids.
- Potentiates the uptake of other nutrients like Nitrogen.
- Vital in the formation of Sulfur-Containing Defense Compounds (SDCs)
- Powerful organic fungicide.
Sulfur clearly plays a big role in the optimal function and adaptability of plants.
In the garden, sulfur should be added to your yearly routine when you suspect a deficiency of Sulfur. Symptoms of soil deficient in Sulfur include yellowing of leaves and interveinal striping (veins will turn yellow as the tissue between remains green) in new growth. Leaves that are older will typically remain green. The tips of new leaves may become brown, crispy, and potentially necrotic.
Some families of plants require more Sulfur than others, so let's take a look at those plants that should be getting more Sulfur each year. As we reduce Sulfur-Containing emissions, soil will inherently be reduced in the soil over time.
- Cabbage, Mustard, Oil Producing Plants such as Flax, Linseed, Sunflower, Cereal Grasses, Peas, Alfalfa, Peanuts, Vetch, Beans, Kentucky Coffee Tree (Yup! It's related to peas!), Clover, Hyacinth Beans, Lupine, Locust
- Those are just the common ones you're likely to run into.
The aforementioned plants need a lot more Sulfur than others. In fact, Sulfur is most critically needed within the first month after germination. As you can see, Fabaceae is a heavy hitter with many different species under it's umbrella. Not all pod-forming plants are in that family, so double check first or ask here and I'll try and help you out!
Remember, ALL plants require Sulfur but some require it moreso than others. Sulfur is not always included in your Fertilizers, so this is something you're going to want to check the label for.
If a chemical contains (S) which is the elemental symbol of Sulfur, or you see the word Sulfate, Sulfite, Sulfide, then it contains Sulfur in different iterations.
Fungicidal Uses:
Sulfur does indeed have some antifungal and antibacterial properties. Sulfur is capable of disrupting activation of some molds and spores. It must come into contact with them in order to properly work, and that's why dusting Sulfur is the most effective means of application. It can also be mixed with distilled water and sprayed on diseases plant tissues.
Sulfur does less of "curing" and more of preventing the spread of mold and fungi. It prevents spores from "germinating".
As an anti bacterial, Sulfur inhibits the growth of bacteria.
Sulfur is an excellent example of a contact and preventative fungicide. If you have a serious infection of a plant, you're going to need to consider using a systemic fungicide which transport fungicide through the xylem of the plant directly targeting infected tissue. Carbendazim and Methyl Benzimidazole Carbamate are some common ones.
Keep in mind that just like in us humans, fungi and bacteria develop resistance to antibiotics in plants as well. So don't overdo it with fancy systemic products, and certainly don't use them when there is no infection, although some people do. I'm not here to shame you for your personal choices. Just... Be smart and use them sparingly if you can. We don't need the plant version of COVID popping up in 2023.
What to Expect After Resolving an Issue?
Firstly, expect affected foliage to most likely die off. Plants are masters of energy and nutrient conservation. Once a deficiency presents and yellowing leaves occur, the yellowing will likely not reverse. The plant knows this leaf is damaged and will take steps to shunt and remove nutrients and energy stored in these affected leaves and return it to the plant to create new healthy foliage.
You'll notice the effects of Sulfur as soon as the next leaf presents itself. A return to green veins, better growth, reduction of tip browning and necrosis, and a healthier plant can be expected.
Common Sources of Sulfur:
Sulfur is available in many forms which I offer most of here.
Options: Sulfur (Raw and Simple), Gypsum (Calcium Sulfate), Langbeinite, Aluminum Sulfate (You'll see this advertised to change the color of your Hydrangeas), Ammonium and Potassium Sulfates, and More!
*Grab a free sample of Sulfur for reading this article. Seriously. Included in your order, or with no purchase necessary. Use Code: TRYSULFUR during checkout. You'll have to cover shipping, but you won't be charged for up to 1 Sulfur Sample in your cart. Valid for 7 days after this article is published.
Effects of Sulfur on Bioactivity:
Sulfur does have an effect on the Bioactivity of your soils. Some nematodes are affected by Sulfur, some good some bad. Not all effects of Sulfur in plants and organisms are fully understood. We're still learning, just as you are here.
Sulfur plays a role in the biology of your soil and the critters that live in it. From microscopic to visible with your eyes, microbes do a lot of unseen work. They break down organics, separating Sulfur from molecules over time, and some are involved in the transport of Sulfur containing compounds through the soil. As I mentioned before, a reduction in atmospheric Sulfur has led to, over time, a more dependant ecosystem on the Sulfur contained in the soil.
Some studies have shown that particular mycorrhizal fungi such as Glomus sp. can deliver as much as 25% extra Sulfur to plants. That's huge! Just another notch in the belt of Mycorrhizae if you ask me.
Frequently Asked Questions:
Q: How do I apply dusting Sulfur?
A: Simply use a soft bristled brush or paintbrush, dip it in the powdered sulfur, and gently dust on both the underside and top side of affected foliage no more than once every 2-3 weeks.
Q: What's the cheapest form of Sulfur?
A: Elemental Sulfur is typically one of the most affordable, along with other forms of inexpensive Sulfates.
A Look at Next Week's Blog:
Myco and Endo Mycorrhizae and it's Role in Plant Health
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