Abstract
The addition of approximately 0.8 mM cobalt chloride to the casing in Agaricus bisporus cultivation causes a delay in the initiation of fruiting and a decrease in yield. Surprisingly, the addition of approximately 1.0 mM cobalt chloride to the casing often has far less apparent effect on mushroom initiation and yield. The cobalt from the casing is concentrated in the fruiting bodies. Ethylene is capable of reducing the cobalt-induced delay in the initiation of fruiting. However, since fruiting occurred even at high concentrations of cobalt, ethylene does not seem to be required for fruiting. The phenomena are reproducible, but some mushroom varieties are apparently more affected than others.