Not taking time to do some research but are Black Oats a grass? Also not taking time to reread the Sharpen label which I have read many times in the past but I don't remember Sharpen by itself having much grass killing activity or preemerge activity on grass. I do know it is labeled on some grass crops. I am fairly sure the Sharpen on rye deal would be with other products in the mix. Are you asking about cereal rye or rye grass? Cereal rye should be killed fairly easily with glyphosate. Rye grass around here it doesn't look like anything is sure to kill it.