Well, I planted my first 2 patches of chufas this year and would have to say I'm puzzled a little. I planted 1/2 acre in 2 different areas, one was a pre-existing field and the other in an old grown up area. I was able to disc and till the old field into a great seed bed, while the other was turned and disc but was to rocky for the tiller. Both patched came up great, but the field one had lots of grass and broad leaf. I sprayer both with a generic 24d and clethodium, which killed the grass and weeds. Problem is that it killed the chufas in one field but not the other. Any ideas of how that could happen?