Experiments were conducted in 1998 & 1999 using artificial rainfall from overhead irrigation comparing Steward^TM (Indoxacarb), with and without surfactants, to two cotton insecticide standards (i.e. Karate^TM or Karate-Z^TM & Tracer^TM). The test in 1998 was designed to look at the effect of the amount of rainfall on this new compound and the two insecticide standards. Two different levels of rainfall were used in this test (i.e. 0.5 in. & 2.0 in.). The test conducted in 1999 looked at the effect of drying time after insecticide application on rainfastness of Steward^TM and the standards. Three different drying times were used for this experiment (i.e. < 1.0 hr., 2.0 hrs. & 24 hrs.).

These two experiments suggest that Steward^TM does as well or better than the current cotton insecticide standards in terms of residual and rainfastness. In 1998 there was no significant difference in Indoxacarb activity loss between the three rain treatments (i.e. no rain, 0.5, or 2.0 inches of rainfall). In 1999 there was no significant difference in activity loss of Steward^TM when allowed to dry 2 hrs. vs. 24 hrs. before rainfall was applied. However, a drying time of less than 1 hour was detrimental to all 3 insecticides tested. Certain surfactants may provide additional rainfastness for Indoxacarb particularly at its recommended lower use rates for cotton.
Analytical analysis of Indoxacarb found on cotton leaves in 1999 correlated reasonably well with biological mortality data. Thus, as is expected, the more active ingredient on the leaf the higher the mortality. A multi-variant model for Indoxacarb deposition based on the analytical data showed that rate, use of adjuvants, and plant part sampled (i.e. leaf vs. square) all had a significant effect on residual deposit of Steward^TM on leaves.