In the 17th century, a term was coined to refer to any elusive malevolent force, but later it was used to describe a condition that afflicts plants, whose origin is not yet fully understood and believed to be caused by the atmosphere. This condition is commonly associated with the browning and discoloration of leaves and shoots, brought about by various factors, including infestations by aphids. In plant pathology, however, the term is only applicable to certain diseases that have the potential to cause severe outbreaks, such as Phytophthora infestans or potato blight and Erwinia amylovora, also known as fireblight, which attacks pear trees, among others.