Ultra violet light (UV) is now being promoted as an alternative to chemical pesticides in the prevention of fungal diseases, especially powdery mildew, in viniculture where most of the research has been conducted so far.
UV light lies just outside of the visual spectrum having a shorter wavelength than we can see and it is often split into three phases: A,B and C.
The shorter the wavelength, the more energy the light carries and the more disruptive it can be to organic molecules.
There is some work to suggest that increased exposure to UV-B (320 – 290 nanometres) can be detrimental to plant health so the use of the correct wavelength is critical to treating the plant.
One company that is developing the practical application of this to food production is UV Boosting of Saint-Nom-la-Bretèche, just to the east of Paris.
High energy light source
UV Boosting use UV-C, which has a wavelength of 290 – 200nm, a part of the spectrum which has been shown to stimulate plants’ natural defences.
By activating this mechanism before infection or stress occurs, plants become more resistant to damage, and not just from pathogens, they are more able to resist frost and water stress as well.
UV Boosting has already sold a number of its kits which are working within the wine, soft fruit and ground care segments with users applying in four to seven treatments during the season to evaluate the impact of the technology on yield.
The treatment provides short exposure to proprietary UV sources on plants after which the plants experience a peak of salicylic acid production.
It is known that salicylic acid is a key plant hormone required for establishing resistance to many pathogens, so as a result of this stimulation the plant reacts to biological or physical threats much more efficiently and rapidly.
Benefits of UV application
Wine growers have confirmed less yield losses due to water stress or fungal diseases. In Bordeaux, it has shown that the treatment offered a 22% increase in yield resulting in €4,900 savings/ha for vineyards
The UV Boosting Helios implements can be easily mounted on standard (narrow) tractors and straddle tractors for application in vineyards. Treatments are conducted at a speed of 4 km/h.
While the equipment is at present limited to specialist applications there is obviously the potential to expand its use into more mainstream crops.
