Reactions of Mycorrhizal Fungi and Mycorrhiza Formation to Pesticides

Abstract

Agricultural chemistry blossomed after World War II, and increasingly sophisc ticated chemicals for pest control have since proliferated. In retrospect, chem­ ists, agronomists, and resource managers seem to have been overly optimistic about the promise of agricultural chemicals as simple solutions to complex pest problems during the early part of this new era in agriculture. It is now apparent that pesticides can have unforeseen effects on nontarget organisms and can thereby influence crop productivity as profoundly or even more so than do the pests they are intended to control (e.g. , 3, 4, 40, 99, 107a, 125, 132). As Rodriguez-Kabana & Curl (125) aptly phrased it: most pesticides act upon a great many organisms for which the chemicals were not specifically formu­ lated, and this has resulted in altered biological phenomena which can be favorable or unfavorable to pathogen activity and disease development. We have seen that nematicides affect fungi, fungicides affect nematodes and nontarget fungi, and herbicides affect both of these as well as host physiology.