Innovative Techniques for Managing Dollar Spot in Warm- and Cool-Season Turfgrasses: The Case of UV-B and UV-C Irradiations

The management of Dollar spot, the fungal disease of turfgrasses, is complicated and, today, tends to include new eco-friendly approaches. The aim of this study is to evaluate the effect of UV-B and UV-C lamps against the infection of Clarireedia species in warm- and cool-season turfgrasses. In vitro tests were performed to evaluate the growth of C. jacksonii mycelium on Potato Dextrose Agar, irradiated with UV-B and UV-C at heights of 5 and 15 cm, 5 s per day for three consecutive days. The same treatments, prolonged for seven days, were applied on naturally infected potted Agrostis stolonifera and Cynodon dactylon × C. transvaalensis, for in vivo tests. Disease severity, antioxidant capacity, and pigment content were assessed at the end of the experiment. Only UV-C reduced the growth of C. jacksonii after 48 h at 5 cm (−36%) and 72 h at both distances (−15 and −27%). Agrostis stolonifera showed symptoms, reduced by UV-C at 5 cm, and fungal structures, except in UV-C exposed samples. Total antioxidant capacity increased after UV-B exposure at 5 cm (+10%). No variations in terms of photosynthetic pigments were observed. These results confirm the potential of UV-C lamps for the containment of Dollar spot.