Manganese deficiency
Nutritional Disorder
Symptoms
Deficiencies result in slow growth, delayed maturity and a high percentage of thick necked bulbs at harvest. The older leaves develop interveinal chlorosis, which progresses to a tip-burn, and they may curl and eventually become necrotic. Onions are very sensitive to manganese deficiencies.
Control
It is difficult to increase the amount of manganese available in the soil. For this reason, treat a manganese deficiency using foliar fertilizers. This is the most effective in a young crop. Foliar spray of MnSO4 @ 0.3% twice at fortnightly interval.