Magnesium deficiency shows up as a yellow and / or browning around the outer part of the leaf, especially in older leaves. Organic based liquid magnesium chelates work faster than Epsom salts and can also be applied to foliage. Organic based liquid trace elements chelates can be applied as a foliar spray for better result Yates Magnesium Chelate is designed for correcting magnesium deficiency, a particularly common deficiency in gardenias, tomatoes, citrus and other fruit trees. The fast acting, easy to use liquid formula is suitable for watering can and foliar spray application for excellent results.