Martin R Fletcher

Hi all I am pretty new to stock photography so after reading the photo requirements I went ahead and submitted some phtoto's. One was accepted and two were rejected for noise so not bad for first attempt. I was looking at the photo below to try and correct the noise but I am having difficulty in identifying the problem and was wondering if someone with more experience could lend a hand. The photo was shot 1/250 at f/5.6 with an ISO of 200, any help would be much appreciated.