To my knowledge, no one has developed a method to separate wheat grains with karnal bunt from non-infected grains. One of the challenges is that karnal bunt is a 'partial bunt' disease---the fungus may form spores only in a small portion of the seed. Partial bunted grains are hard to see and that feature increases the difficulty in ensuring removal of 'bunted' seeds from healthy seed lots.

Finally, I do not know where you got your information that eating bunted seeds is damaging to humans. Consumption of wheat grains infected with a bunt or smut fungus does not cause disease in humans (or animals). One example of the lack of toxicity is corn smut---the smutted grains are considered delicacies by some. In Mexico, they sell 'corn smut' soup.

As far as wheat--the smut (or bunt) spores will result in wheat flour that is discolored (brown to tan) and it might smell like fish (due to polyamines in the spores), but it is not toxic--just unpleasant. Wheat seed lots with bunted wheat grains are not sold due to sensory defects.

Thanks virginia for such a valuable information. I have noticed few farmers complianing rashes on hands while handling afected seed lots. I will follow those in order to know what actual cause it may be, bunted seeds or any thing else.

Bunted grains could be separated by using salt solution.

I agree that floatation might be possible with a complete bunt (100% of grain filled with spores). Would that work for partial bunt (~0.1% of grain volume) containing spores?