i've been back to 2 of my properties that i treat, i have seen a little henbit and poa. for first fall pre-emergent app i did a split app of pre-m, then second treatment 6 weeks later i used the split app rate for stonewall (i just was trying to use up what i had). I treat these 2 other yards at the same time as i do my own yard.. and my yard is clean as a whistle, i do nothing extra. can't figure this out. I used same product, same rate on my yard and the 2 others. I know that with first pre-emergent we had rain the next day,second time out no rain for a while. I remember after a few days with no rain i went and watered my lawn to make sure it would get into the soil. We have had alot of rain this winter, i started to think mabee it is breaking down the pre-emergent faster.. and the other mistake i think i made is that i put my first pre-m app down the first week in sept, but followed up with the second 6 weeks later, which was around mid october.. so thinking i was to early with the 2nd? but like i said, my lawn is clean as a whistle and i used same products at same time (still waiting for weeds to come up here, but none yet).. all i can think is the lack of water on those other lawns could have hindered the results, one is a rental and i know for a fact they don't water, the other has irrigation system, but i know it was broken for a while.. anyways, this definetly hasn't been good for the old self esteem. lol.