An investigation on effectiveness of iron phosphate against Deroceras agreste in lettuce fields of Mazandaran and Tehran provinces Abstract
Deroceras agreste (L.) is a pest of lettuce in different regions of Iran and world. Theirdamage is feeding from leaves, stems, roots and seeds.The aim of this study was todetermine the effectiveness of iron phosphate in comparison with registeredmolluscicides against D.agreste in lettuce fields of Mazandaran and Tehran provincesduring 2007-2008. The field studies were conducted according on randomized completeblock design method with four treatments and four replications. Treatments were ironphosphate baits (pellets 1%) at dose 5 gr/m², metaldehyde bait (2.5 gr/ m²), carbaryl bait (3 gr/ m²) and control. The percent of slug mortalities in all treatments were foundsignificant at α=5% (p<0.05). iron phosphate applied (5 gr/ m²) caused 65.40 % mortality and that of metaldehyde (2.5 gr./ m²) and carbaryl (3 gr./ m²) were 74.93% and 71.61% respectively. In Sari, Mortality percentage of iron phosphate (5gr/m²) was singnificantly higher. control (71.26%) as compared with metaldehyde (70.42%) and carbaryl (68.06%) treatments. Application of 5gr/m² Iron phosphate and 2.5gr/ m² metaldehyde and 3gr/ m² carbaryl were placed in group of A, B and C respectively, by Duncan test. It was proved that mortality of slugs increased as time passed regardless of doses (Iron phosphate) and was found max. in day 14 of sampling. Percent mean of slug mortality in Sari region was higher (69.91%) compared with that of observed Varamin (71.38%) regions. In total, results of present study indicated that, Iron phosphate 5 gr/m², due to possessing the least environmental pollution, among the registered molluscicides and because of its higher efficacy in wet condition can be recommended against D. agreste in lettuce fields of Iran.