Also, fewer mushrooms are produced which reduces greatly the already weak biological efficiency of this mushroom. The yellow oyster is not as prolific as the other Pleurotus mushrooms in the conversion of substrate mass to mushrooms. Usuallly after the second flush very few mushrooms form. There was the first flush of oyster mushrooms back in May, as you might recall. Then, there was a second flush. Then, there was a second flush. And then a third.