HEPIA
Geneva School of Agricultural Engineering

The aim of this work is to test three prototype UV lamps with wavelengths of 222 nm, 275 nm and 310 nm, provided by Future of Grow (FOG), a company based in Aigle, Switzerland. The goal is to determine the efficacy of these lamps in controlling various pests and pathogens, namely powdery mildew and mites, on strawberry and Cannabis crops.

This work has given an idea of which UV treatment is the most effective, which will make it possible to produce usage sheets specifying the amount of energy, the hanging height and the application time for each type of lamp for commercial purposes.

In the study on strawberry plants, the lamp model emitting at a wavelength of 275 nm and using a dose of XXX mJ/cm2 proved the most promising. With this treatment, the plants showed a significant reduction in average chlorophyll loss throughout their growth, compared with untreated plants or plants treated with Armicarb®.

In detail, the treated plants lost on average 104.215 mg/m2 less chlorophyll than the untreated plants, and 27.011 mg/m2 less than those that received the Armicarb® treatment (p = 0.00002).

Furthermore, the different UV exposure methods had no significant effect on the dry mass of the strawberry plants (p = 0.167) or on the sugar content of the fruit (p = 0.784). In the Cannabis trial, the UV treatment that produced the highest proportion of healthy plants (free of powdery mildew) was the one using a wavelength of 310 nm with a dose of XXX mJ/cm2, with 90% healthy plants (p = 0.009).

This proportion was not statistically different from that obtained with the Armicarb® treatment. As regards mite infestations on the apical part of the plants, the treatment using a wavelength of 310 nm with a dose of XXX mJ/cm2 showed the lowest proportion of mite attacks, with 80% of plants remaining healthy (p = 0.022).

By contrast, the Armicarb® treatment recorded the lowest proportion of unaffected plants, with only 40% remaining free of attacks.

No significant variation was observed in stem diameter growth (p = 0.598) or in chlorophyll development (p = 0.059) among the various UV treatments and the positive and negative control groups in the final experiment on cannabis plants, at the doses tested.

UV radiation revealed aspects of agronomic interest, whether in controlling powdery mildew, managing mites, increasing chlorophyll concentration in strawberry plants, or the absence of stress at these specific doses.

However, further tests are essential to determine whether these UV prototypes are optimal and what their real benefit is.