Determination of the weeds in lettuce fields in Muğla province and herbicides which can be used against these weeds

Lettuce (Lactuca sativa L.), belonging to Asteraceae family, is an annual broad leaved vegetable. Besides pests and diseases, weeds are among the factors negatively affecting yield. Weeds not only inhibit plant growth by nutrient, water and light competition, but also cause secondary damage by hosting pests and disease agents. In order to determine the important weed species in 62 lettuce fields in Muğla province, surveys were performed in lettuce fields of Dalaman, Fethiye, Köyceğiz, Marmaris, Menteşe, Milas, Seydikemer, Ula and Yatağan districts in 2018 growing period. As a result, Cyperus rotundus, Matricaria chamomilla, Sorghum halepense, Avena sterilis and Tribulus terrestris were determined as the most common weed species with 100% frequency of coincidence. Among them, density and coverage area of the first three weed species were also higher than the others. It was also aimed in the study to determine a herbicide which can be used against these weeds. In accordance with this goal, efficiency of two herbicides; 915 g/l s-Metolachlor + 45 g/l Benoxacor and %60 Benfluralin, which were not registered for lettuce areas, were determined against these weeds by field trials performed in two different fields in Fethiye district, according to randomized complete block design with three replications. As a result of the trials, it was found that both herbicides could not satisfactorily inhibit weed growth, and weed densities were not statistically different from those in control parcels. No negative effect of the herbicides on lettuce growth was observed.