The use of benomyl to control infection by vesicular–arbuscular mycorrhizal fungi



The effect of the fungicide, benomyl, on vesicular arbuscular (VA) mycorrhizal infection and phosphorus uptake was studied in two pot experiments, using pea Pisum sativum L., mustard Sinapis alba L. and red clover Trifolium pratense L. Benomyl was either incorporated into the soil or sprayed on to the surface of the pot. Benomyl had no effect on concentrations of water-soluble P in soil but reduced VA mycorrhizal infection and P inflow in pea. Mustard plants were uninfected even in untreated pots and benomyl had no effect on P inflow in mustard. In clover, there was a positive correlation between shoot P concentration and percentage of root length infected with VA mycorrhizal fungi. Copper, zinc and manganese concentrations in clover shoots were affected by benomyl but this may not have been related to mycorrhizal infection. Benomyl is recommended as a treatment to control VA mycorrhizal infection, with many fewer undesirable consquences than result from soil sterilization.