Is the given picture in the details crabgrass?

Question

Our lawn is starting to get some other type of grass growing and we can't figure out what it is. I took pictures of it and was wondering if someone can identify it and if so how to get rid of it. We think it is crabgrass, but not sure. Our original grass is tall fescue.

Here are the flickr pictures with the unidentified grass being highlighted:
http://www.flickr.com/photos/sgrobins/1150888264/in/set-72157601503077546/
http://www.flickr.com/photos/sgrobins/1150018547/in/set-72157601503077546/

Answer 1

Determine if this is crabgrass. Crabgrass is not shade tolerant, and grows best in full, hot, mid-summer sun. Cover a patch with light proof material for 10 days. Crabgrass will not tolerate the shade but well rooted perennial lawn grasses will recover if denied light only 10 days.

The presence of this weed usually indicates the original grass was mowed to short however your grass does not look either thin or short (less than 3 inches). But crabgrass will invade an overwatered lawn that has a shallow, weak root system.
Grass needs only 1inch of water per week.
Test your sprinklers output by placing several tuna cans about the yard and water just as you usually do. Measure the water's depth in each can. You may have areas that receive too much water.

Crabgrass is an annual in most areas unlike most other lawn grasses so is killed by freezing temps. Control is to use a preemergent. If it can't germinate it can't invade. Crabgrass seed germinates when forsythias are in bloom roughly mid-May. So you will need to apply pre-emergents sometime from late April to late May.
One last thing crabgrass likes a soil slightly more acid than most lawn grasses. Current "data indicate that crabgrass shoot and root growth was insensitive to soil pH values ranging from 4.8 to 6.3." So this annual is happy on any thing from very acid to slightly acid. Lawn grasses like a pH closer to neutral at 6.5. If you havn't done a pH test on your soil it might save you time, money and effort in the long run.
A soil test will give you a custom report for all your fertilizing needs: N-P-K & pH. This report will tell you how much lime and nutrients to apply for the year.

Answer 2

Young crabgrass looks like regular grass, just wider and more yellow-green. Crabgrass has a star-shaped growth pattern when it's mature. When you pull mature crabgrass, often part of the star clump will pull up and the rest will remain. All parts have their own roots. Conveniently (for the plant) each part can live on with its own roots after other parts are pulled. Devious, isn't it.

Answer 3

Yes it looks like the dreaded crabgrass for sure. I have tons of it in my lawn. I spray it with weed and feed, and other treatments, and it just stays. best bet is to dig up that patch and reseed.

Answer 4

http://www.abateaweed.com/images/photo-large-crabgrass2.jpg Picture of crabgrass