There are a couple different fungal leaf spot diseases which present similar symptoms similar to what is in the picture. I would guess that what you are experiencing is strawberry "Leaf spot" but it might also possibly strawberry "Leaf scorch". Thankfully the management is pretty similar for both issues.

Both fungi are more successful when conditions are consistently wet. So, if the weather is drier next year it many not be as big of any issue. Similarly anything you can do to keep the leaves of the plant dry will discourage the fungi. For example, using drip irrigation opposed to over head irrigation might be helpful.  Thinning the plants to allow more airflow through the patch would also help by lowering the humidity.

We have a factsheet on strawberry diseases which goes into more detail on the issues and list both organic and conventional chemical controls.   It can be found here:http://www.ext.colostate.edu/pubs/garden/02931.html
 

I hope this helps, please let me know if you have any further questions.