Kathy, I replied to your support form that you sent in about this issue.
If anyone else has this problem, I'll need the following information:
If your game restarted with a "quick infection message", please tell us what the message was (as precisely as possible, please)! There's a
seed catalog in the Plant Tycoon Guide forum. Is it possible for you to look at that and pinpoint which seed you believe was the cause?
Thank you!

~Heather