US (IA): How to tackle magnesium deficiency symptoms

Iowa is finally getting some nice warm, in some cases hot, sunny days. This reigns in the importance of irrigation and supply of nutrients to plants for rapid growth and development. Nutrient deficiencies often show up with rapid plant growth. One that's being observed now is magnesium deficiency.

A typical indicator of magnesium deficiency in vegetables is interveinal chlorosis which develops between the leaf veins (first image). Due to magnesium’s mobility in plants, symptoms will typically affect older leaves first. Prolonged deficiency will eventually lead to death of the tissue (second image).

Magnesium deficiency is widely observed in vegetable crops, particularly pepper and tomatoes due to their nutrient high requirements. To address deficiency soluble magnesium sources, for example Epsom salt, could be used both foliarly or through the drip. Foliar applications are effective but must be applied in low concentrations to avoid phytotoxicity. For smaller areas and backpack type operation, mix 1 lb of Epsom salt in 5 gallons of water and spray uniformly. For fertigation apply 15-25 lbs of actual magnesium per acre.

Source: Iowa State University