Lawn Problems Part 1
Have this weed growing between houses in generally shady area. Normal grass has died in this area. I do cut my grass short. Photo 1 and 1a taken today just after mowing. What weed is this? What treatment might be best?
Based on your photos this looks like it may be crabgrass. This is a summer annual weed and will dieback with the frost frost. Mowing the lawn too short favors its growth. At this point, you may want to overseed and fertilize to thicken your turf and mow at the proper height. See our key practices for a healthy lawn - seeding, fertilizing, mowing, etc. http://extension.umd.edu/hgic/lawn-and-garden/lawn-care
Select recommended tall fescue cultivars. Tall fescue grows best in full sun to part shade. Fine fescues such as hard fescue grows best in the shade. http://www.mdturfcouncil.org/resources/Documents/TT-77%202017.pdf
Also, if you have not tested your soil within the last several years, results will give pH, liming and fertilizer recommendations. http://extension.umd.edu/hgic/topics/soil-testing
Since crabgrass is a summer annual, the best way to control it is to apply a granular, preemergent crabgrass control product in the spring. Applying crabgrass preventer too early and too much spring rain are reasons why crabgrass can be a problem even though a preemergent was applied. For season long control two applications may be necessary. Make the first application when forsythia is blooming than again about 6 weeks later. Check the label of the product you select for information. Choose a product that does not contain nitrogen fertilizer. http://extension.umd.edu/hgic/topics/crabgrass