The genus, currently thought to contain 51 species,[2] may be broadly divided into three ecologically based groups - mycopathogens, entomopathogens,[3] and plant pathogens and related saprotrophs.

[4] However, the genus has undergone recent revision into which most entomopathogenic and mycopathogenic isolates fall into a new (unrelated) group called Lecanicillium.

[6] First identified from potatoes in Germany in 1870, this disease affects a variety of cultivated plants and can persist as a saprotrophic soil organism for more than 15 years.

Identification can be made by looking for one-celled conidia, hyaline round to ellipsoid which are formed at the tips of whorled branches.

The sapwood has greenish or brownish streaks, and the infection can take a few years to progress to the rest of the tree or move rapidly.