When most people envision their ideal lawn it is an even field of green grass, uniform in species, color, and length. And many people work very hard to achieve that fantasy yard. Unfortunately, there are many things that can ruin the perfection, from weeds to rogue grass types to discolored spots. If your otherwise healthy lawn is developing yellow to brown spots, there could be a variety of potential causes. Luckily, most of them are treatable, especially if you catch them early.