I have experience with poa annua. I am going to assume they behave the same way. The only think that makes me unsure it is pia is the lack of seed heads. If and when you see those, you'll know what I'm talking about and it is definitely poa. Poa will die off in the heat of the summer because of its shallow roots. Since it is in a shady area, I don't know if that will happen in your yard. I have heard to bag your clippings as that helps the seeds from spreading. I cannot speak to the effectiveness of this. The only thing I can tell you works for sure is a good pre-emergent. I used a leaving product faithfully since last fall and the only poa in my Bermuda lawn is where the grass is thin. Definitely a night and day difference from last year. Sorry as this may not give you much help for what to do to get rid of it this year now that you have it.

Ok, so I got my results of the soil test back from UMass. Here are the results: -------------------------------------- Linestone and fertilizer recommendations for established turfgrass Apply 50 lb of calcitic limestone/1000 sq ft. Lime may be applied at any time, but mid-autumn or early spring is best Recommendation: 3 lb/1000 sq ft P205, and 4 lb/sq ft K20. To provide the above recommendations you may follow the directions below, or you may devise your own fertilizer program using the recommended amounts of phosphorus (P205) and potassium (K20) along with one pound of Nitrogen per 1000 sq feet. It may necessary to raise nutrient levels over several applications. Apply a 20-3-12 fertilizer @ 5 lbs/1000 sq ft in late April, late June, and very late August. If more convenient you may substitute the late April recommendation with the same application made 1 to 2 weeks after your last fall mowing. Follow these recommendations for two years. Retest the following year. Consult the interpretation sheet enclosed or obtain one of the turf guides referenced on the backside of the interpretation sheet. Micronutrient(ppm) Boron: 0.1 Manganese 1.3 Zinc 0.5 Copper 0.3 Iron 31.0 Sulfur 15.0 Soil Ph 6.1 Nitrogen: No3-N = 0 ppm BUffer pH: 6.7 Organic Matter 3.1% (desirable range 4 - 10%) nutrient levels (ppm) Phosphorus: 1 Potassium 45 Calcium 219 Magnesium 83 Cation exch Cap 4.0 meq/100g Percent base saturation K = 2.4, Mg = 13.9, Ca = 22.5 Micronutrient levels : all normal Extractable aluminum 128 ppm (soil range: 10 - 250 ppm) THe lead level in this soil is low. --------------------------- If I want to use organic fertilizer, do you have any recommendations for brands? Since I have missed the recommended late april application, can I apply one now, and still apply another in late June? If I apply the suggested lime amount, how will that affect the pH level? I am thinking of overseeding with kentucky bluegrass in the fall. Also i noticed in their interpretation sheet they mention that a Cation exch capacity of 10 to 15 is typical. and values below 6 may indicate the soil will have trouble supporting good turf growth unless special management techniques are employed. Should I be concerned? how can I increase this value?

Thanks for identifying this plant. You seem to be right! I've started treating it and it appears to be killing it off.

here are few more photos these are in my backyard. seem like the same plant. 1st one is 7 inches tall and the other 2 photos seems like the same plant but fully matured.