My parents are on vacation and left me to care for their house and garden. I've been watering their plants and fruit trees almost every day and noticed that some of their Asian Pears are turning black! I've never had a green thumb and usually unintentionally kill every plant I come in contact with. The pears are fine but start to turn black from the base then the blackness spreads to the rest of the fruit. Finally when the pear turns completely black they fall off the tree. They've had this tree for years and this has never happened. I had planted a pumpkin plant not too far away that grew white moss all over it. Yesterday I removed the pumpkin plant thinking it spread its disease to the tree. What could it be and how do I stop it?

Help!!