Pre-harvest UV-C treatments

Impact of UV-C radiation applied during plant growth on disease susceptibility and fruit quality of strawberry fruit

before and after harvest.

In Fluxen, we are always looking for solutions to the major concerns of our customers and, one of the most demanded are disinfection devices to avoid contamination in certain tests or work rooms where the balance of microorganisms is very delicate, that is, there are microorganisms that are used and others that contaminate those who want to study.

On the other hand, then there are the rooms that want to avoid the proliferation of any type of pathogens, so they need to have a daily cleaning protocol or even after each use of the room or instruments.

Also another demand from our customers is for pre and post harvest UV-C application in the horticulture sector either for trials or for the production chain at the commercial level.

At the beginning of the 20th century, the German researcher Hertel, using a prism, defined UV-C light as the most efficient for killing bacteria, but it was not until 1910 that Cernovedeau and Henri conducted the experiment of water disinfection using UV in Marseille, France. Austria and Switzerland soon joined in the disinfection of water with UV light. In 1916, it was used for the first time in Henderson (Kentucky) in the United States for the same purpose. Subsequently and even in the 1940s, the competition of disinfection by chlorine slowed down the use of UV, this is due to the reduction in the cost of chlorine production, of which the use intensifies due, in particular, to the fact that its disadvantages were then unknown. In the 1950s it was already well established that UV radiation was effective in disinfecting air and surfaces. By 1954 it was already being used to disinfect air in air-conditioning units.

Since then, the use of UV has spread to many, many applications in various sectors, and UV-C in particular is used in water disinfection, air and surface sterilization and, to a lesser extent, in horticulture, since its use on living organisms can alter their organoleptic or physical properties. This “fear” has generated various opinions regarding its use, but the reality is that it is very beneficial if applied in an automated and fully controlled manner by means of control systems, such as those developed and manufactured by Grupo Incore (Alicante-Spain).

The article that is announced at the top of the post is about the pre and post harvest use in strawberries, research carried out in France in June 2020.

The conclusion of the study is very interesting because depending on when and with what radiation (dose) it is applied, there are different results in terms of physical development of the plant, productivity, quality and defensive action against the pathogens deliberately infected by the researchers in the study.

The conclusion is summarized here:

Pre-harvest UV-C treatments had some significant effect on plants and reduced the natural occurrence of diseases such as powdery mildew on leaves. As for the fruit, pre-harvest UV-C treatments had a significant effect on color and there was a significant reduction in natural infection by pathogens such as Rhizopus spp.
Further experiments will be conducted to confirm this encouraging result with artificial inoculum of Rhizopus spp. and P. aphanis.
It seems difficult to find a single UV-C treatment that is optimal for all measured parameters, such as plant disease resistance and fruit quality.

In our study, we demonstrated that it is preferable to apply UV-C treatments before flowering to increase flowering and plant yield, but it is preferable to apply UV-C after flowering to reduce leaf susceptibility to B. cinerea infection.
In addition, UV-C treatments applied before harvest seem to be promising in terms of crop quality, but further evaluations are needed to find optimal UV-C treatments that can also have an impact on strawberry fruit.

Obviously, as the study says, more studies are needed to prove the effectiveness of such treatments.

At Fluxen, we have our 20W device, Purgato 254 developed for manual or automated surface disinfection by UV-C radiation at 254nm peak. This device is the safest on the market as standard as it has a built-in motion sensor and can also be daisy-chained to create an automated system for larger surfaces or rooms. Therefore, it could be automated by a PLC or other control system to be turned on/off daily at times when staff are no longer present or when staff decide to disinfect manually because they require it at that time.

With LED technology, several products are already being developed with UV-C and UV-B ranges for the stimulation of the production of secondary metabolites beneficial to plants and their application depending on the type of crop or objective of the researcher.At Fluxen, we develop customized devices and luminaires with LED technology in the lengths available in the market and adapted to the range that researchers want to explore.

Ref: https://apsjournals.apsnet.org/doi/pdf/10.1094/PDIS-02-20-0306-RE

Authors: M. Forges, M. Bardin, L. Urban, J. Aarrouf, and F. Charles / Year of publication: June 2020