Crop-related charms were a series of Charm's devised to alter some characteristics of crops (most likely growth rate, shape, strength, etc.).
In mid-1998, the Ministry of Magic report A Study into Muggle Suspicions about Magic recommended that the International Confederation of Wizards impose an immediate ban on further crop-related charms until the fuss among Muggles about so-called "crop circles" — actually entries in the Annual International Wizard Gardening Competition — died down.
Behind the scenes
Crop circles are patterned formations made in crops such as wheat or barley, which look like merely flattened crops from the ground but can be seen properly from the air. Conspiracy theorists have believed these formations are caused by aliens or other paranormal sources, though most have been proven or are generally believe to be man-made.
- Daily Prophet Newsletters (Mentioned only)