Also known as Epsom salts, MgO is necessary for the colouring of leaves. Heavy rain will readily wash MgO out of light soils and can also be low when potash or high-potassium fertilisers have been used.
MgO deficiency can affect vegetables like cabbages, lettuces and potatoes, fruit such as apples, cherries and grapes. Leaves turn yellow between veins and around the edges, and may eventually turn red, purple or brown. Apply as a foliar spray or spread over the soil.
Application rate: 17g sq. m. Rake in well.