## 3 Results
### Analysis of Group of Experiments: Experiment C  
Significant differences (F = 2.69; \(p\) = 0.0406) were found between the treatments in semi-field trials for the percentage of attacked plants after 24 h Attacked plants were found in all treatments except in the positive control (see Figure 3A). The lowest intensity of slugs' attack (only \(4\pm 4\%\); N = 25) was found after 24 h in the treatment where the combination of techniques was used. In the same period, \(20\pm 6\%\) (N = 25) of the plants were attacked in the negative control. Significant differences for the intensity of slugs attack (F = 6.44; \(p\) = 0.0017) were found between the treatments after 48 h as well, and slugs attacked plants to a certain extent in all except positive control treatment (see Figure 3A). When the combined method was used, the intensity of the slug attack was the lowest (\(12\pm 8\%\), N = 25). This treatment differed significantly when compared to the negative control (\(32\pm 5\%\), N = 25) and dusting (\(28\pm 5\%\), N = 25). Significant differences for the intensity of attack (F = 57.83; \(p\) < 0.0001) were found also between the treatments after the third observation (72 h), and slugs attacked plants in all treatments besides the positive control (see Figure 3A). When a barrier was used in semi-field trials, only \(20\pm 0\%\) (N = 25) of attacked plants were recorded, while in the same period \(64\pm 4\%\) (N = 25) of attacked plants were observed in the negative control (see Figure 3A). Analysis of the percent of damaged plants revealed significant differences (F = 2.77; \(p\) = 0.0453) between the treatments after 24 h The lowest damage occurred after 24 h in treatment with combined techniques, where only \(2\pm 2\%\) (N = 25) of the plants were damaged by slugs, while \(15\pm 5\%\) (N = 25) of the plants were damaged in negative control in the same period (see Figure 3B). Significant differences (F = 17.42; \(p\) < 0.0001) were found after 48 h between the treatments for damaged plants. Combined treatment was the least affected, with only \(4\pm 2\%\) (N = 25) of the plants damaged by slugs, while in the same period \(32\pm 5\%\) (N = 25) of the damaged plants were found in the negative (see Figure 3B). Significant differences for plant damage (F = 58.54; \(p\) < 0.0001) were found between the treatments in the last observation (after 72 h) as well. Wood ash as a barrier alone or in combination with dusting proved to be the most effective method, since in both cases, it resulted in only 10% (N = 25) damaged plants, while in the same period slugs damaged \(50\pm 4\%\) (N = 25) of the plants in the negative control (see Figure 3B). Figure 2: Efficacy of wood ash as a physical barrier. The means marked with different letters significantly differ at \(p\) = 0.05 ([PERSON]’s multiple range test) between the treatments in periods of 24 and 48 h.  
Slugs significantly affected the total yield (F = 6.24; \(p\) = 0.0020) of lettuce seedlings (see Figure 4). Combined techniques were the best protective method against the slugs since the highest yields were measured in this treatment (34 \(\pm\) 4 g plant), while the lowest yield was measured in the negative control (15 \(\pm\) 5 g plant). The yield of the healthy leaves differed also significantly among the treatments (F = 20.34; \(p\) < 0.0001). The highest yields were measured in the positive control (25 \(\pm\) 2 g plant), and the lowest were obtained in the negative control (5 \(\pm\) 2 g plant). There were no significant differences between the barrier alone (20 \(\pm\) 1 g plant) or the combined method (20 \(\pm\) 2 g plant); however, both methods proved to yield more healthy leaves than only the dusting of slugs (11 \(\pm\) 2 g plant) (see Figure 4). Significant differences (F = 15.05; \(p\) < 0.0001) for a yield of the damaged leaves were found between the treatments.