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Iron Deficiency


Iron Deficiency

Usually appear in

Summer to Autumn

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Caused By:-     Usually due to Soil ph being above 7


Iron deficiency is not a pest as such, but is a symptom that there is something wrong, usually with soil nutrients. It can easily be mistaken for manganese deficiency, but in this case all leaves are usually affected. All plants need iron to grow, but some plants have a higher need for iron and can easily show signs of iron deficiency. The most susceptible of these are plants that grow in acidic(ericaceous) soils such as Azaleas, Camellia, Gardenias, Hydrangeas and Citrus. Other plants like roses, raspberries and fruit trees also needs a high iron content in the soil otherwise apart from the usual symptoms the fruits will be of poor quality. If these plants do not receive enough iron for whatever reason they show signs of yellowing leaves, especially younger ones, starting with leaf tissue between the veins. The leaf veins are usually darker and the last to go yellow. If iron deficiency is severe the entire leaf may become yellow then the edges become brown eventually older growth of the plant is affected. This condition is known as Iron Deficiency or Iron Chlorosis. Iron Deficiency is more often found where soils are highly alkaline. If the pH of the soil is too high it ties up the iron making it unavailable to the plants. Iron is required for the formation of chlorophyll and for respiration and therefore photosynthesis. Iron deficiency in the soil is rare, but it is often unavailable for plants to absorb if soil pH is above a neutral ph of 7. The ideal ph for growing plants is a ph between 5 and 6.5. Also, iron deficiency can develop if the soil is too waterlogged, anaerobic or has been over-fertilised. Certain elements like calcium, zinc, manganese, phosphorus, or copper can tie up iron if they are present in too high concentrations in the soil. Watering ericaceous plants with water from sources where there is plenty of calcium, such as rain water from roofs with cement tiles, tap water or often well water will induce iron chlorosis. Iron can also be lost from the plants roots where there is excessive watering or long periods of rainfall. Iron is also essential for disease resistance. Picture by Division of Plant Industry Archive, Florida Department of Agriculture and Consumer Services,


Iron deficiency can be avoided by choosing appropriate soil growing conditions for example avoid growing acid loving plants on lime soils. If this is not an option grow them in pots sunken in the ground where the soil ph can be controlled. Adding well-rotted manure or compost to any soil will help prevent this deficiency. As a temporary quick fix iron sulphate can be used to correct the deficiency. Chelated forms(Ferrous Sulfate (FeSO4)) are preferable since they are created in a form that more readily gives up its nutrient. It is best to foliar feed this compound especially if the soil ph is above 7, because in such soils its iron will quickly transforms to Fe3+ and precipitates out as one of the iron oxides thereby becoming less available to the plants. If changing your soil ph to an acidic one is impractical the addition of acidic acidic mulches such as conifer leaves or bark or adding an acidifying fertilizer such as sulphur, aluminium sulphateAl2(SO4)3 or ammonium sulfate(NH4)2SO4 can be used to help maintain low soil pH levels. In some parts of the world some the use of these fertilisers are banned for various reasons.

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