Try using different angels to take the picture. Sometimes it's inevitable, especially with plants, and thats okay. Try darkening that spot a little, to try and make it not stand out. Plenty of pictures have mergers, most actually, you just have to try to eliminate them by camera angles. Or darken the spot.
For your background, I see it a little bit. But it isn't that bad. I actually talked to the judge about it, and it wasn't a Factor when it came to placing.
Remember, the point of these contests is to learn
and therefore improve our photography
You can call me Bob