In addition to Itai's answer, Photoshop's "Magic healing brush" or other-brand equivalent, can do this reasonably well, and gives you a greater degree of manual control than the fully automated tool. In most cases this is not necessary, but it's good to have "another string to your bow" when desired.
MHB is a clone tool that copies material from an area of your choice under user 'brush' control, but as well as being able to select brush diameter and % transparency of the written overlay, the tool melds the written and selected areas when you finish a "pass" (release mouse button usually). In examples like the one you have given the spot is far enough away from material which differs from what is going to be overlayed that you can do it without using a mask to restrict the writing behaviour. But, if you are near a boundary (eg grass to gravel transition in your image) the tool tends to include averaged material from the undesired area (eg here gravel colouring in grass). This can be overcome by using a selection tool to select an area in which writing will occur and this also stops material outside the selected area being auto-magically included. It's easier to do than to explain.
@MattDm would like me to suggest Irfanview for this - but it does not do it well.
I'd post an example removal on your image but I've just changed PC's and I have not yet reloaded Adobe's fine products on this PC.
Just for Matt:
This is what you can achieve with Irfanview with a little work. Much better if much longer taken.
Far harder and far less good than using MHB or Itai's method.
I've added a bonus 'deer' into your original :-) (more visible on large version).
Larger version here - a closeup look at the changed area on the larger version will show some fairly gross patching.