Poa Annua is a cold season weed. Once the temps get consistently warm/hot it will eventually die off. If you want to kill it before then you need to use a liquid treatment called Image. However, I would suggest not using Image at this point in the game because it is the growing season and all you want to do in the spring is apply positive things to your yard such as fertilizer, water, and soil enhancements. The best way to beat Poa Annua going forward is to use Pre Emergent. Pre emergent does NOT kill weeds, it simply prevents weed seeds from germinating. The best pre emergent for this is a liquid application called Dimension 2EW. It's a tad expensive, but a tiny bit goes a long way! I use this product March 1, June 1, September 1, and December 1 every year and I have like zero weeds, ever. Your basic yard needs 3 main ingredients including water, fertilizer, and pre emergent. If I had to choose only 1 of these 3 ingredients to apply to my Bermuda lawn it would be pre emergent hands down. Pre emergent is God's gift to Bermuda grass. Conquering weeds is about staying ahead of them and not waiting til they arrive. Anyway, I hope this helps. Good luck!