Question
What specific effects does the Panama disease have on banana plants? How does it harm the plants?

Answer
Dear Emma, Panama disease is a soil borne fungus, extremely resistant to fungicides, that apparently attacks the banana plant through the vascular system.  The first effects are a yellowing of the lower leaves, followed by continued yellowing of younger and younger leaves, eventually causing the collapse of the entire tree.  The stem of infected bananas turns red upon cross-section.  It is an extremely devastating disease and has been known to destroy entire crops of banana trees.  That being said, as you live in Massachusetts, you have nothing to worry about.  This disease is fairly specific to much warmer regions of the world.  Currently, I believe there is an outbreak in Southeast Asia, but the US should be safe as regards this disease.  I hope this answers your concerns.  Melissa