Hello Jimbobbob,
welcome to the forum!
Good to see that you are interested in the vegan and vegetarian lifestyle
To answer your question, we try to do what we can.
Similarly as we normally do not refuse to drive our cars (which are made using animal products) on roads (that are made using animal products), we normally try to eat (preferably locally grown) fruits and vegetables, well knowing that some *might* have been grown using animal products. It is sad a reality of life that the animal industry is so insidious that they try to find whatever use for their waste products, thus contaminating a lot of other products.
So we normally try to avoid the large amount of animals being killed specifically to produce meat, dairy and eggs and accept the small amount of animal (waste) products that might have been used in producing the vegetables and fruits that we consume.
If the issue truly concerns you, however, you can search for "veganic agriculture" ... there are some, e.g. co-operatives that manage to grow fruits or vegetables without animal products. (On a sidenote, I have not heard so far about any fruit trees where animal waste products are used as fertiliser).
Or you could grow your own fruits and vegetables at home. You would be surprised to find out how much fruits and vegetables can be grown in small areas without having to use animal products.
I don't have time right now to search for the correct examples, but e.g., have a look here:
Lessons from an Urban Back Yard Food Forest Experiment - The Permaculture Research Institute
