MICROFLORA OF TURFGRASS TREATED WITH FUNGICIDES

Fungicides are used widely to manage high-quality turfgrass, but their use could adversely affect the composition of microbial populations. Fourteen fungicides, a nematicide, and five mixed fungicide programs were applied to turfgrass for 3 yr and were tested for their effects on numbers of bacteria, actinomycetes and fungi, and N concentrations. Combinations of fungicides suppressed fungi and stimulated bacteria and actinomycetes more than individual toxicants. Collective microbial groups were generally less affected by each fungicide than were individual species within each group. The rate of decrease of NH+4 concentrations in fertilized turf (presumably via nitrification) was only slightly influenced by fungicides. The more harmful effects of some fungicides to turfgrass may involve induced acidity rather than direct suppression of specific microbial groups. © 1979.