I know it is hard to determine a weed from a description, but maybe I will
get lucky. First a little background. I am in Zone 7. I have an El Toro
lawn, which was sodded 20 months ago. Last year was the first full year for
the lawn. Around July of last year, a weed or grass started growing in the
lawn, which I would like to identify and kill.

The weed has a cylindrical stem, sort of like a dandelion, but much thinner.
A couple inches up the stem several grass like leaves/limbs/branches branch
out. The top of the stem has a brown seed cluster. About 7 to 10 days
after mowing, the seed head will be visible and if I go about ten or more
days between mowings, it is taller than the El Toro, and then gives the
whole lawn a brownish look.

Any clue what this could be? I would like to see if I can identify it and
do something to prevent it from sprouting this year. Last year I should have
brought a sample to the extension office, but kept procrastinating.

Billy