Yes it did increase the risk. Before the green revolution there were a lot of very different wheat varieties around the world. In fact, if my memory is correct

Yes it did increase the risk. Before the green revolution there were a lot of very different wheat varieties around the world. In fact, if my memory is correct, during the selective breeding for high yields one of the breakthroughs came from a thick and sturdy stalked dwarf wheat from Japan. The stalk genes it had produced a stalk strong enough to carry the new large yields. The point being, we used to have a large variety of geno and phenotype around the world, and now we don't.