Answer.: An entire crop can be ruined due to late blight. Many fungus and bacteria are often touted to be carriers that spread this disease.  In the 1840s, the potato blight which now referred to as the light blight killed millions of people in Ireland. Fire blight is also contagious and causes damage to the entire forest area as well if the trees lie close by. The family members of Rosaceae like the loquat, crabapples, quinces, hawthorn, cotoneaster, Pyracantha, raspberry along apple trees and pears are highly affected by the contagious fire blight disease. And of such disease, the spread can be unpredicted as in extremities an entire orchard can be destroyed because of it.