We have a couple big oak trees in our front yard, and the grass is pretty much crap. Lots of weeds and little shutes growing off the oak trees (little oak trees popping up). Well my wife put out a bird feeder, and she throws some seed on the ground as well. In that area all the oak things and weeds have dissapeared, and the grass is nice and healthy, there isnt much there it was all weeds before, but what is there looks good. Is the black oil sunflower the reason?