Where do I apply for the senior farmer vouchers?

I think you are referring to the program to use at at farmers markets for low income elderly folks. That provides coupons worth $40 for use during the summer at the markets. The applications are available at designated locations. Where I live the local senior center handles the paperwork. Try contacting your local Area Agency on Aging for where to.apply. It's a great program provided.by the federal government and helps local farmers.

I found this page online that describes the program. Contact your local area agency on aging to get more info - it is first come, first served.
http://www.agriculture.pa.gov/Encourage/food/Farmers%20Senior%20Farmers%20Market%20Nutrition%20Program/Pages/default.aspx