Pesticides, Insecticides, and herbicides do not generally pose a problem that would affect mycorrhizal activity. Fungicides, on the other hand, must be carefully selected as mycorrhizal fungi are susceptible to the effects of many of the compounds that have been developed to control root pathogens. RTI is continually testing and evaluating both soft chemical and bio-fungicides. For a current report on fungicidal contact Fernando Morell (fernando@reforest.com)  for an update.