Filterstorm is a brilliant app for colour correction. Its a bit like a mobile version of Photoshop, and is great for colour correction on the move. Its available on IPhone and it rocks on an IPad. Would not worry about the pricey PRO version unless you want to batch process.
http://itunes.apple.com/gb/app/filterstorm/id363449020?mt=8
Start by cropping your shot down a bit, to remove unwanted details / distractions. The crop tool can be found under the option ‘Canvas Tools’.
Under Filters on the left hand side, select Hue/Saturation.
Select the top spectrum icon, and then move the slider down until the preview image looks more natural – this reduces the overall saturation.
Select the bottom blue / yellow icon, and then move the slider up – this removes yellow / adds blue.
If the image looks a bit flat, try the curves option. Move the middle of the curve upwards to brighten the mid-tones and give the image a bit more life.