Man looking at roses: "What can I do about black spot on my roses?"
Frank: "Live with it"
Man looking at me -blankly.
Frank: "Check inside, I'm sure we have a fungicidal spray."
Man drives up in a big pickup, has straw hat.
Frank "You look ready for some serious gardening"
Man in straw hat: What do you know about weeds?"
Frank: "Some, try me"
Man in straw hat: "I've got plantains in my lawn, why?"
Frank: "Plantains thrive in compacted earth and produce bazillions of seeds"
Man in straw hat: "But it doesn't look compacted to me"
Make long story short: How big, how do you use, what kind of grass, did you seed it, how long ago, mow schedule, hmmn, rototill, black plastic, wait till autumn, add compost, reseed, stay off, corn gluten meal, internet....
Man in straw hat: "Nahh, I don't think so."
Frank: "or just use some weed and feed"
Chemical solutions are the easy answer that I find difficult to give, but end up giving anyway.