How to fix no texture trees?

I have this map in which i like to take screenshots in, but recently the tree texures have gotten outdated or something, when i look at them from far they look fine but if i get close to the trees the leaves turn into the no texture orange, any way to fix it? oh and the map is called Car Dealership (showroom) i dont wanna ask the author as that might be annoying for them, i want to fix the textures myself, could anyone just tell me how to do it.
Thanks

 

Surely good sir you are aware that nearly all authors within this community are merely human? They are beings just as you and I, and respond to those reaching out in a similar manner.
There is no annoyance to a message received unless it is inherently 'annoying,' they shall reply to it in their own time and at their own pace.

You will be surprised at the individuals you can approach in life, if you simply attempt to forge a connection.