What does it do?
Important for photosynthesis, as it is an enzyme activator during the production of chlorophyll. Manganese is also a component for the structure of chloroplasts and is closely related to Iron
What do you see?
A pattern of chlorosis on the newer leaves starting at the tips. This can be quite distinct, with leaf veins remaining green while interveins pale and yellow out.
What can you do?
Check soil pH. A high pH will make Mn uptake difficult. Foliar spray with an all-purpose micronutrient complex containing Iron and Manganese such as Spray-N-Grow or Mineral Matrix.