study of control methods and economic injury level of slugs pest on lettuce in mazandaran province

two slug species (parmacella ibera and agriolimax agresteris) from parmacelidae and ‎limacidae families were found dominant injuries slugs in nursery and field conditions during ‎2001-2003. different methods of control under field condition in grakheil station of sari vicinity ‎studied. the experiment conducted in complete randomized block design with eight treatments and ‎four replications. each replicate consist of the three meters in length and 50 cm in width and lettuce ‎plant to plant spacing of 25 cm. in total 36 lettuce plants cultivated in each replicate. means were ‎compared using duncan’s multiple range test (p? 0.05). the results indicated that maximum ‎damages according leave injuries and minimum lettuce yield obtained for ploughing treatment, ‎which 27.3 percent damages with lettuce yield 29.1 ton per hectare. min. damages with max. yield ‎found with metaldehyde, methiocarb and iron phosphate treatments, with two percent and nine ‎percent damages and lettuce yield 39.3, 39.1 and 36.2 ton per hectare, respectively. metaldehyde ‎and methiocarb were the best treatments for control of slugs. among the various control methods, ‎the percentage of loses at the beginning of the injury was lowest for methaldehyde (4.3 percent) and ‎highest for the thick rough rope (15.5 percent).‎