Effect of Water Dilution Types on The Physico-Chemical Properties and Bio-efficacy of Some Insecticides Against Potato Tuber Worm, Phthorimaea operculella (zeller) at Field.

The work was conducted in zagazig district, Sharkia governorate on potato plants (Kara variety) during summer plantation in 2014 and 2015 seasons. The present work aimed to study the impact of water dilution type (Nile and ground water) on physico-chemical properties, residual effect and bio- efficacy of insecticides against potato tuber worm Phthorimaea operculella (Zeller).The results showed that effect of Nile water on emulsion stability, wherever Roxy  diluted with Nile water gave cream layer 2 ml equal acceptable limits while with ground water gave cream layer 5 ml above limits. On the other hand, Malathate with two water types not gave any separation and creaming layer. The addition of Nile water increased surface tension in case of spray solution of Malathate, Runner, Roxy, Tracer, Penny and Proklame compared with ground water. Also, addition Nile and ground water to different insecticides increased foam volume with Proklame and Roxy amounted 53 and 49 cm and 8 , 17 cm , respectively, while other treatments  gave lowest foam volume. The PH values lie between very acidic in case of Roxy with N. water and G water (2.3 and 2.5) respectively and Malathate (3.9 with N water and 5.5 with G water). On the other hand , Runner and Penny recorded PH value ranged between 7.1 to 8.0 but Proclame  and Tracer recorded slightly basic (8.9 , 8.7) and (8.1, 8.1) with Nile water and ground water, respectively compared with Nile water and ground water alone without insecticides 7.4 and 8.0. The suspensibility percentage, viscosity increasing with ground water compared with Nile water but density increasing with Nile water than ground water. Concerning the efficacy of the tested insecticides in controlling P. operculella larvae differed significantly . Concerning effect of Nile and ground water on efficiency of insecticides on corrected mortality % on  P. opercullela larvae after two application. The results illustrated that corrected mortality percentage in treatments sprayed with pesticides mixed with nile water was higher (about two fold) than pesticides mixed with ground water in the two seasons, where proklame, Tracer, Pinny, Roxy proved to be the most effective materials. This reduction due to the high decrease of surface tension in ground water than Nile water. Also foam was high for proklame with Nile water and ground water represented by 53 cm and 49 cm respectively. In addition suspensibility percentage increased in Nile water than ground water, PH affected when addition Nile and ground water.
     The obtained data concluded to preferred  use Nile water  in binary mixture with tested insecticides only and prevent use ground water.