DEPRESSIVE EFFECTS OF DIODE LASER ON SELECTED WEEDS IN FIELD CONDITIONS

This study investigates the depressive effects of diode laser radiation on commonly found weed species in the Northwest Anatolian conditions. Unlike previous laboratory-based experiments, this pilot study conducted in natural environments aims to understand weed reactions to laser application under field conditions. Cleavers (Galium aparine), small scabious (Scabiosa columbaria), and sun spurge (Euphorbia helioscopia) were selected for observation. A diode laser (5500 mW power, 450 nm wavelength) was applied to plant apical meristems and stems at four doses for each species. Regression analyses using dry-based remaining biomass and laser doses were performed with the logistic growth model. The ED90 values, indicating a 90% reduction in plant growth on the stem, were determined as 14.42 J for cleavers, 11.04 J for scabious, and 18.04 J for sun spurge. For apical meristem applications, plant growth reduction was less than 90% at maximum energy doses, with rates of 72.18% for cleavers and 41.64% for scabious. These results support the thesis that laser application to the apical meristem region of the weed may not be sufficiently effective beyond the cotyledon period. However, the study concludes that laser application to the plant stem can successfully control all three weed species.