Impact of spirotetramat on the growth of beneficial microorganisms

Studies were conducted to evaluate the compatibility of spirotetramat 150 OD with beneficial microorganisms, viz., Trichoderma viride, Beauveria bassiana, Metarhizium anisopliae and Pseudomonas fluorescens under laboratory conditions in Coimbatore, Tamil Nadu, during 2007–2008. Radial growth of T. viride and M. anisopliae in spirotetramat at 75 g a.i. ha⁻¹ was 18.33 and 20.00 mm, respectively, at 72 h of inoculation with the untreated check recording 46.00–48.00 mm. Growth of B. bassiana in spirotetramat at 45, 60 and 75 g a.i. ha⁻¹ was 18.33, 14.00 and 8.67 mm, significantly lower than that in untreated check (28.00 mm) at 10 DAI. Spirotetramat was incompatible with T. viride, B. bassiana and M. anisopliae, but relative compatibility was significantly better than other insecticides at 45 g a.i. ha⁻¹. Spirotetramat at all the doses did not inhibit P. fluorescens and was highly compatible.