Magnesium deficiency

• Role in the plant: magnesium is an essential element for the process of photosynthesis (because it forms part of the chlorophyll molecule) and is also involved in protein production. Magnesium is therefore essential to plant growth, particularly during tuber bulking.

• Symptoms of deficiency: the bottom leaves first present mild interveinal, pale-green to yellow chlorosis (photos 1 and 2) which subsequently turn brown and finally become necrotic (photos 3 to 5). Such lesions are not unusual on potato plants, during the last part of the growing season, particularly on some cultivars. Lesions are typically located on the central part of the leaflets, except on the veins of the older leaves (as magnesium is highly mobile in the plant).