Modern agriculture and horticulture increasingly use substances that are not classic plant protection products, but have a significant impact on the physiology and quality of crops. This group includes ethephon (2-chloroethylphosphonic acid), which is classified as a systemic growth regulator. Its special role is that it is easily absorbed by plants and, after application, releases ethylene, a natural phytohormone. Ethylene affects a number of physiological processes in plants, including, above all, fruit ripening.
As a result, ethephon has found wide application in vegetable and fruit production, especially where uniform and accelerated ripening of the crop is of key importance. This is particularly important in the case of species (such as tomatoes and peppers) where uniform color and ripeness are not only a market requirement but also an element of effective protection against losses caused by disease.
Ethephon has been registered in many countries for use on various crops, such as fruits, vegetables, cereals, and oilseeds.
Mechanism of action of ethephon
Ethephon is a highly water-soluble compound which, after penetrating plant tissues, decomposes to release ethylene, phosphoric acid, and chlorides. Of these, ethylene is the most important because it acts as a natural growth regulator.
Ethylene has many functions as a phytohormone in plants, including:
- initiating and accelerating the fruit ripening process,
- stimulating the aging and falling of leaves,
- it regulates germination and flowering processes,
- it influences plant responses to environmental stresses (e.g., drought, salinity, pathogen infections).
In practice, this means that the application of ethephon allows you to control certain physiological processes that would occur more slowly or unevenly under natural conditions.
The use of ethephon in fruit and vegetable crops
The use of ethephon in fruit and vegetable crops brings visible benefits, primarily in accelerating and standardizing fruit ripening. Thanks to this solution, producers can achieve the following effects:
- Uniform yield – the fruit ripens at a similar rate, allowing for a single harvest. This is particularly beneficial for farms focused on supplying raw materials to processing plants, where product quality consistency is required.
- Increased commercial value – uniform fruit color (e.g., intense red in tomatoes or peppers) increases their attractiveness to customers, which has a positive impact on their market price.
- Loss reduction – shorter ripening time reduces the risk of fruit infection by pathogens such as Botrytis cinerea (gray mold) and Alternaria spp. In practice, this means less need for fungicides and reduced losses during storage.
- More efficient harvesting – uniform fruit ripeness allows for more efficient organization of the harvesting process, which translates into lower labor costs.
Applications of ethephon in cereal cultivation
Fruits and vegetables are undoubtedly among the main areas of application for ethephon, but this substance also plays a significant role in cereal cultivation. Due to unfavorable weather conditions, which often occur during the period when cereals are heading, plants are exposed to lodging and bending of stalks to the ground, which leads to significant yield losses.
In the later stages of cereal growth and development, auxins dominate. They stimulate intensive growth of the main shoot while inhibiting the development of side shoots. High concentrations of these hormones can also negatively affect root system development.
Ethephon is a substance used in cereal cultivation that can regulate the action of auxins. Numerous studies and experiments confirm its multidimensional benefits.
By inhibiting the production and transport of auxins, ethephon supports the development of side shoots and stimulates the growth of adventitious roots. An additional advantage of this substance is its ability to quickly and effectively stop the growth of stalks during the most intensive period of their elongation.
The effect of ethephon application is slight lignification of tissues, which leads to their stiffening and mechanical strengthening of the stalks. Shorter and more stable stalks contribute to better transport of nutrients and water to the ear, which translates into more efficient use of resources.
Ethephon and plant protection
Ethephon is not a classic plant protection product, as it does not act directly on fungi, bacteria, or insects. Its role is mainly to indirectly support protection by shortening the period during which fruits remain susceptible to infection.
Accelerating ripening with ethephon means that fruit reaches harvest maturity faster and can be picked before pathogens attack.
In this way, ethephon can be considered part of integrated plant protection, supporting the action of traditional fungicides and improving overall production efficiency.
Safety and restrictions on use
Like any growth regulator, ethephon requires precise dosing. Excessive doses can cause undesirable effects, such as premature fruit drop, deterioration in fruit quality, or accelerated plant aging.
In accordance with European Union regulations, ethephon is registered as a growth regulator, and its use is subject to compliance with waiting periods and permissible residue levels in crops. In practice, this means that farmers must use it in accordance with the registration label, and applications should be made at the appropriate stages of plant development.
Ethephon – planned legislative changes
When the European Union renewed its approval for ethephon (Commission Implementing Regulation (EU) 2023/2591), the European Food Safety Authority (EFSA) recommended lowering the acceptable daily intake (ADI) for this substance. Based on the reduced ADI in 2024, EFSA reviewed all maximum residue levels (MRLs) for ethephon.
The European Commission also consulted the EU reference laboratories for pesticide residues on the need to adjust certain limits of determination. These laboratories proposed product-specific limits of determination for ethephon that are analytically achievable, ensuring compliance with updated safety and monitoring standards.
The European Union plans to introduce new maximum residue levels for ethephon in many products from January 2026.
On September 19 this year, the Council of the European Union received a draft regulation amending Annexes II and V to Regulation (EC) No. 396/2005 of the European Parliament
and of the Council as regards maximum residue levels for dimoxystrobin, ethephon, and propamocarb in or on certain products.
The European Commission has notified the World Trade Organization (WTO) Sanitary and Phytosanitary Measures Committee (SPS) of its intention to amend the maximum residue levels for ethephon (G/SPS/N/EU/801).
The revised MRLs will have a particular impact on blueberry exporters, for whom the MRLs will be reduced to the limit of quantification.
On June 23, 2025, the European Commission published a corrigendum stating that the MRLs for ethephon in nuts (except hazelnuts and walnuts) are also being reduced to the limit of quantification.
It was also proposed to lower the MRLs for apples, pineapples, rye, and wheat. However, the MRL for barley will be increased.
Table 1. Planned changes to maximum residue levels of ethephon in food products (source: www.agrinfo.eu)
| Group | Products | Ethephon (mg/kg) | |
| Current NDP | Planned NDP | ||
| Nuts from nut trees | almonds, Brazil nuts, cashews, chestnuts, coconuts, macadamia nuts, pecans, pine nuts, pistachios | 0,1 | 0,02* |
| Pome fruits | apples | 0,8 | 0,7 |
| Berries and small fruits | blueberries | 20 | 0,01* |
| Various fruits | pineapples | 2 | 1,5 |
| Cereals | barley | 1 | 1,5 |
| rye | 1 | 0,8 | |
| wheat | 1 | 0,5 | |
* Limit of detectability
Suppliers of apples, pineapples, rye, and wheat should review their current use of ethephon and assess whether any changes to current good agricultural practices will be necessary to ensure compliance with the new maximum residue levels. For suppliers of blueberries and nuts, it is particularly important to assess their current use of ethephon and consider potential alternatives, pending changes to the MRLs.
In addition, the EU also proposes to lower the limit of determination for a wide range of products:
– for fruit, vegetables, cereals, sugar crops, and animal products from 0.05 to 0.02 or 0.01 mg/kg,
– for oilseeds, oleaginous fruits, tea, coffee, cocoa, and spices from 0.1 to 0.05 mg/kg.
Summary
Etefon is an important tool in modern fruit and vegetable production. As a growth regulator, it works by releasing ethylene, which accelerates and evens out fruit ripening, improves their commercial quality, and facilitates harvest organization. In addition, it promotes phytohormones, which shorten and stiffen cereal stalks, preventing lodging. This translates not only into economic benefits, but also into better protection of plants against losses caused by disease.
Although it is not a typical pesticide, its importance in agricultural practice shows that the regulation of plant physiological processes can be as important as chemical protection. When used properly, ethephon therefore becomes a valuable element of a sustainable agricultural and horticultural production system.
At the Hamilton UO-Technologia laboratory, we test for ethephon residues in fruits, vegetables, and cereals, and the testing method we use has a detection limit that meets both current requirements and future, more restrictive standards.
If you have any questions or concerns, J.S. Hamilton Experts are at your disposal.