Stem galls of coriander (Coriandrum sativum) is caused by

Stem galls of coriander (Coriandrum sativum) are caused by Protomyces macrosporus.
Stem gall caused by the fungus Protomyces macrosporus L. is a serious disease of coriander damaging all the aerial plant parts incurring heavy losses as the market value is reduced.
In India, the stem gall disease of coriander was reported for the first time from Pusa (Bihar) by Sydow and Butler (1911).