Q.Gladiolus’ change to a pinkish color after two years
After my gladioli grow the second year, the third year all the flowers that grow are a pinkish rose in color. What causes this? We plant around 600 hundred each year. Also, what anti-fungal powder do you recommend to use on the gladioli when storing them for winter?

This is not uncommon for some flowers including Glads.
Here is a link that explains a few of the possible reasons.
https://www.gardeningknowhow.com/plant-problems/environmental/fixing-color-faded-flowers.htm
The corms can be dusted with any type of anti fungal power, found at most garden centers.
https://www.gardeningknowhow.com/ornamental/bulbs/gladiola/storing-gladiola-corms.htm