Copper deficient plants have chlorotic younger leaves, stunted growth, delayed maturity, excessive tillering, lodging and sometimes brown discoloration. Copper deficient plants are prone to increased disease. 
 
Copper deficiency in barley
(photo courtesy of PPI)
Barley with yellowing leaves from copper deficiency
Copper deficiency in wheat
(photo courtesy of PPI)
yellow brown leaf tips of copper deficient wheat
Copper deficiency in wheat
(photo courtesy of PPI)
yellow poorly filled grain heads of copper deficient wheat
Copper deficiency in wheat
(photo courtesy of PPI)
Yellowing wheat leaves from copper deficiency
Copper deficiency in wheat
(photo courtesy of PPI)
Yellowing wheat leaves from copper deficiency
Copper deficiency in wheat; brown discoloration in the field.
(photo courtesy of R. Engel)
brown discolored wheat grain in section of field from copper deficiency