Molybdenum (Mb)

Marijuana Horticulture

by Jorge Cervantes

Molybdenum is seldom deficient. It is part of two major enzyme systems that convert nitrate to ammonium. This essential element is used by cannabis in very small quantities. It is most active in roots and seeds.

This micronutrient is almost never found deficient in cannabis. Deficiency promotes nitrogen shortage. First, the older and middle-aged leaves yellow, and some develop interveinal chlorosis; then the leaves continue to yellow and develop cupped or rolled up margins as the deficiency progresses. Acute symptoms cause the leaves to become severely twisted, die, and drop. Overall growth is stunted. Deficiencies are worst in acidic soils.

Excess is uncommon in marijuana gardens. An excess of molybdenum causes a deficiency of copper and iron.