Symptoms
Leaves are small and pale green to yellow in color when nitrogen is deficient. Symptoms are first seen in the old leaves and gradually progress to new growth. The plant appears thin and upright.
With severe deficiency the old leaves become completely yellow or turn brown before dropping from the plant. Stems and veins look purple.
Reasons
Nitrogen deficiency.
Sulfur deficiency is similar in appearance to nitrogen deficiency, however it starts on younger leaves because sulfur is not as mobile as nitrogen within the plant.