Effectiveness of UV-B irradiation on controlling powdery mildew and white rust of wasabi seedlings (Eutrema japonicum (Miq.) Koidz.)

Abstract

We investigated the effectiveness of Ultra violet B (UV-B) irradiation on controlling powdery mildew (Oidium matthiolae Rayss) and white rust (Albugo wasabiae Hara) of wasabi seedlings. The seedlings were irradiated with UV-B for 1 h from 23:00 to midnight at a distance of 100 to 200 cm from the irradiation source. The irradiance ranged from 2.4 to 40.8 μW·cm^–2. High efficacy was observed in this irradiance range for control of powdery mildew and not for the control of white rust. Furthermore, reduction of seed germination, growth inhibition or leaf damages of seedlings were not observed in this study.