Frequently Asked Questions

Questions about Sulfur in Agriculture

What role does sulfur play in modern agriculture?

Sulfur is one of the essential plant nutrients, recognized by FAO as an essential secondary macronutrient. It is involved in fundamental processes such as sulfur amino acid synthesis, enzymatic development, chlorophyll formation and fruit quality improvement.

In addition, sulfur is one of the most widely used active ingredients in plant protection worldwide, approved as a fungicide and acaricide due to its contact efficacy and low risk of resistance. It serves a dual purpose—nutritional and plant protection—making it a versatile and indispensable resource in modern agriculture.

Since when has sulfur been used in agriculture?

Agricultural use of sulfur dates back to the 19th century, documented in early formulations designed to control powdery mildew and other fungal diseases. The EPA has registered its use as an active ingredient since the 1920s, and the European Union maintains its approval as an active substance after continuous scientific evaluations.

Its long history of use reflects its proven efficacy, its low toxicological complexity, and its continued usefulness even after the advent of modern synthetic fungicides.

What does it imply that sulfur is a natural or non-synthetic product?

It means that elemental sulfur comes from a mineral resource and not from a chemically engineered molecule. In European regulations, sulfur is classified as an authorized natural substance, which allows its use in organic farming.

Unlike synthetic compounds, their fungicidal effect derives from simple physicochemical properties that have been known for more than a century. Being natural implies a toxicological profile that is more stable and easier to evaluate.

Why does organic farming allow sulfur to be applied to crops?

Regulation (EU) 2018/848 explicitly authorizes the use of sulfur in organic farming because it is of mineral origin, effective, and essential for controlling powdery mildew. The EGTOP technical group considers it a fundamental input in organic farming, highlighting its efficacy, environmental compatibility, and low risk of causing resistance.

It is one of the few active substances with simultaneous approval in conventional, integrated and organic systems, which demonstrates its cross-cutting agronomic importance.

Why is sulfur sometimes associated with oil or GHG emissions?

The relationship arises from its industrial origin: much of today’s commercial sulfur comes from oil and natural gas desulfurization processes, according to the USGS. It is an unavoidable by-product of refining, creating an indirect association with the fossil fuel industry.

However, elemental sulfur is not a greenhouse gas according to IPCC and EPA. Emissions linked to sulfur come from industrial sulfur dioxide, not from the agricultural use of solid sulfur.

What are the main applications of sulfur in agriculture today?

Sulfur has three main areas of application:

1) Plant nutrition: corrects deficiencies, improves protein synthesis, and contributes to the color, flavor, and quality of the fruit.
2) Soil management: corrects high pH, reduces salinity, and improves soil microbial activity.
3) Plant protection: an internationally approved fungicide and acaricide, with particularly high efficacy against powdery mildew and plant-feeding mites.

Its combination of functions makes it a strategic input with multiple benefits in different crops.

What exactly does it mean that sulfur powder is a good fungicide?

This means that there is scientific and regulatory evidence supporting its efficacy in controlling fungi such as powdery mildew. It acts through contact and volatilization, preventing the development of mycelium without penetrating the plant tissues.

Its multi-site mode of action prevents fungi from developing resistance easily. The EPA and the EU consider it one of the most widely used fungicides due to its efficacy, availability, and safety.

What are the properties of sulfur powder as an acaricide?

Sulfur is a contact acaricide officially authorized by the European Union and the EPA. It is effective against common phytophagous mites in citrus, fruit trees and grapevines, among others, interfering in their metabolism and reducing their reproduction and movement capacity.

Its efficacy depends on thorough coverage and moderate temperatures. It is one of the few acaricides permitted in organic farming because it is of mineral origin.

Why is sulfur powder a particularly relevant phytosanitary product?

For three key reasons:

1) Market share: Eurostat places sulfur among the most used crop protection products in Europe, reaching 40% of sales in some countries.
2) Low probability of resistance: its multi-site action keeps it effective decade after decade.
3) Wide regulatory acceptance: it is approved in conventional, integrated and organic.

Its importance stems from its balance between efficacy, sustainability, and availability.

Does its low price mean lower quality or efficacy?

No. Its low cost is due to its industrial abundance and its elemental nature, not to lower quality. The EPA, EFSA, and the European Commission continue to approve sulfur because it meets the strictest standards for efficacy and safety.

The price is not related to its functionality: it is simply a product with an efficient and stable supply chain.

Is sulfur powder toxic?

Sulfur is considered to be of low acute toxicity according to the EPA. The main hazards are associated with eye, skin or respiratory irritation from exposure to dust.

The European Union considers that, under authorized conditions of use and with appropriate personal protective equipment, the risk to operators and consumers is low. Many crops do not even require a maximum residue limit, which enhances their food safety.

Can sulfur powder be used on certified organic crops?

Yes. Regulation (EU) 2018/848 expressly permits its use as a fungicide, acaricide, and repellent. EGTOP identifies it as an essential tool for ecological management due to its efficacy and low environmental impact.

Its use is standard in vineyards, horticultural crops and fruit trees in certified organic systems.

Does it present risks in handling and storage?

Like any powdered substance, it requires basic safety measures:

– Avoid inhalation by wearing respiratory protection.
– Use gloves and goggles to avoid irritation.
– Keep containers closed and in dry, cool and well-ventilated places.

EPA, ECHA and European Commission guidelines agree that, following these measures, the risk is low and controllable.