I am getting a weed in my back yard that I can not kill and do not know what it is. The yard was once a wooded area. I have tried preemergent grab crass killer and weed killer, no luck. It grows in mid to late may. Can you help me? Picture provided
The photo is blurry, but we think it may be stiltgrass, a foreign invasive grass that has spread like wildfire in the past 10 years all throughout Maryland and the East Coast. Here is help: https://extension.umd.edu/hgic/problems/japanese-stiltgrass You'll notice that not all pre-emergents are effective on this grass.
If this does not look right to you, try sending another photo.