Photocatalytic Titanium Dioxide and Ultraviolet Radiation Effects On Sclerotinia Homoeocarpa Growth and Dollar Spot Disease Development.

Photocatalytic titanium dioxide (TiO₂) generates strong oxidative effects when illuminated with ultraviolet (UV) light with wavelengths of less than 385 nm. The oxidative species can react and cause cellular damage to microorganisms, which may reduce S. homoeocarpa growth and help to control dollar spot disease development. This study was investigated in vitro and in vivo. Factorial treatments consisting of 5 rates of TiO₂ and 3 doses of UV radiation were arranged in a completely random design. The in vitro study showed that the mycelia linear extension of S. homoeocarpa was significantly inhibited by UV radiation when combined with TiO₂. The highest UVB radiation dose (0.2754mol·m⁻²·day⁻¹) combined with two TiO₂ rates (1mg/ml and 50mg/ml) resulted in no mycelium growth. Regression analysis predicted that 14 days after inoculation, the mycelium diameter of the highest UV radiation dose without TiO₂ would be approximately 55mm; the non-treated control would be about 190mm. This indicates the possibility that UV radiation might be involved in the overall size of dollar spots. Results were similar in the in vivo study where creeping bentgrass was grown in pots in a growth chamber, and exposed to 3 doses of UV radiation for 12 hours per day and 5 rates of TiO₂. The lowest UV radiation (0.04549 mol·m⁻²·day⁻¹) treatment resulted in the largest infected area (57.8mm in diameter). The other two UV doses (0.1064 mol·m⁻²·day⁻¹ and 0.9444 mol·m⁻²·day⁻¹) had reduced infected area of 38.5mm and 40.1mm. However, there were no significant differences among TiO₂ rates compared to the non-treated control.