Nginx vhost website + wordpress alias in subfolder

I want to create a vhost for a php website in this folder:
/var/www/mydomain.com/home

and an alias for this folder for a wordpress blog:
/var/www/mydomain.com/public_html

I try this vhost:

server {
        listen   80;

        root /var/www/mydomain.com/home;
        index index.php index.html index.htm;
        charset UTF-8;
        server_name mydomain.com;

        access_log /var/log/nginx/mydomain.com.access.log;
        error_log /var/log/nginx/mydomain.com.error.log debug;

        location /blog {
                alias /var/www/mydomain.com/public_html;
                try_files $uri $uri/ /index.php?$args =404;
                location ~ .php$ {
                        fastcgi_split_path_info ^(.+.php)(/.+)$;
                        fastcgi_pass unix:/var/run/php5-fpm.sock;
                        fastcgi_index index.php;
                        include fastcgi_params;
                }
        }

        location / {
                try_files $uri $uri/ /index.php$is_args$args;
        }

        location ~ .php$ {
                fastcgi_split_path_info ^(.+.php)(/.+)$;
                fastcgi_pass unix:/var/run/php5-fpm.sock;
                fastcgi_index index.php;
                include fastcgi_params;
        }
}

With this configuration, my website work fine, the homepage of my blog is OK, static files are OK, the page like http://mydomain.com/blog/wp-login.php are OK, all the admin panel is OK :
http://mydomain.com/blog/wp-admin/
(wp-admin folder exist)

But the page in front of like

http://mydomain.com/blog/terms-and-conditions/

http://mydomain.com/blog/contact/

or all the page with / like blog/…/… always go to my /var/www/mydomain.com/home/index.php

What did I forget to do?