DO NOT use roundup or any other chemicals in your yard. People are always wanting the easiest way to get something done. But you expose yourselves, your children, myself, my children, your chickens, the watershed, your drinking water, my drinking water, etc. Anyone that tells you that using roundup is safe is a fool.
There are these things called 'hands' that people used in the good old days to pull weeds. And in case you haven't noticed, there were no cases of ADHD, ADD, asthma at unbelievable levels, etc., back in the good old days. People think chemical creations are technological advances, but in reality, they are a source of many sociological ills.