Italian ryegrass will definitely blow out the back of a combine.  You'll have it to deal with next year too.  Birds can also spread it.

I prefer to go after it hard in corn because it is much cheaper to control there than it is in wheat.  I have a "zero plants go to seed" policy in corn.  If it is evenly scattered in wheat, then I will spray it there too.  If you ignore it, you will definitely be sorry because it is such an aggressive competitor.  In corn you should expect to spray it at least 2 times.  Once with a burndown and the second pre or post.