recommends a foliar spray of Alpha Chelates Iron (Fe) to treat the symptoms of iron deficiency in plants.
One of the most common of trace element deficiencies, iron deficiency is associated with alkaline growing conditions and is also referred to as lime induced chlorosis. Too much phosphorus or high levels of calcium carbonate in the irrigation water have also been cited as reasons for this disorder.
With most plants requiring around 100 ppm of iron in leaf tissue, deficiencies develop when there is too little soluble iron in the soil solution, when root function is impaired or when a nutrient imbalance renders iron absorbed by the plant, unavailable for a physiological process. Deficiency symptoms may appear when roots are damaged or pruned. Other causes of deficiency are root disease, nematodes, water-logging and fertiliser burn.
Being very immobile within the plant, iron cannot be exported in large amounts from older to new tissues, which means that iron must be continuously absorbed by the roots.
Iron deficiency symptoms typically seen first in the youngest leaves show the deficient leaves developing a pale green to yellow colour because iron is essential for the synthesis of chlorophyll. This chlorotic symptom extends over the entire blade highlighting the veins, which in mild deficiency remain dark green, and in severe deficiency cases, turns the entire leaf a uniform yellow to white colour.
Iron deficiency also causes browning and death of roots starting from the tips, allowing pathogens to gain entry to the plant and result in secondary diseases. Iron toxicity generally only occurs when excessive rates of iron have been applied in a foliar spray or as a root drench, and which is characterised by brown necrotic spots on leaves.
Though iron deficiency is readily recognised from the distinctive leaf symptoms, it is important to know the cause of the disorder to correct the problem. The pH of the soil must be checked and the plant examined for signs of root injury. Leaf analysis can be done to establish whether the problem has been induced by a nutrient imbalance such as excess phosphorus or zinc.
Additionally, a sample of symptom leaves must be collected and the iron content compared with healthy leaves at the same stage of development. Iron deficiency should be treated by correcting any contributing environmental factors such as high pH, compaction, poor drainage or nutrient imbalance.
A foliar spray of Alpha Chelates Iron (10ml/L) will give quick response, with some re-greening of leaves evident within 5 days. It is important to ensure that the spray solution contacts all symptom leaves and is reapplied at regular intervals to satisfy the needs of new growth.
Provided the soil conditions have been rectified and the roots are healthy, a root drench of Alpha Chelates Iron will also assist a deficient plant recover. This treatment will satisfy the needs of the roots and the plant tops but the effect will be slower than can be achieved with a foliar spray.
Alpha Chelates Iron is very stable in high pH conditions and is ideal for use in hydroponic solutions and liquid feeds. This binary chelate of iron is also unusually stable at high concentrations of phosphorus. A concentration of 2ppm Fe in solution is satisfactory for growing most hydroponic crops.