April, 1995 Nutrient deficiency symptoms of AG0257 plants ISSN 1329-8062 David Beardsell, Knoxfield Plants must absorb certain elements to live and grow. Carbon (C), hydrogen (H), and oxygen (O) are the elements supplied from air and water. The growing media generally supplies the remaining nutrients required for plant growth. The major elements or macronutrients required by the plant are nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulphur (S). The minor elements, trace elements or micronutrients necessary for healthy plant production are molybdenum (Mo), copper (Cu), zinc (Zn), manganese (Mn), boron (B), iron (Fe), and chlorine (Cl). Deficiencies or imbalances in supply of these essential elements can cause growth reductions, and in more severe cases visual symptoms are expressed in leaves and flowers. Nitrogen deficiency (N) Nitrogen is required by plants in higher concentrations than any of the other elements, except potassium in certain instances. Plants grown without nitrogen grow very slowly. Plants are stunted and show a general yellowing of the foliage. The symptoms of nitrogen deficiency will first occur in the older leaves. The leaves turn from a pale green Figure 1. Symptoms of nitrogen deficiency include stunted plant colour to a yellow and eventually leaf drop occurs. The growth. The Eucalyptus gunni plant on the right hand side younger leaves remain green for longer periods of time but exhibits this symptom. The plant on the left hand side has an eventually the whole plant exhibits a pale green to yellow adequate supply of nitrogen. colour. Potassium deficiency (K) Phosphorus deficiency (P) Deficiency symptoms of potassium are also exhibited in Deficiency symptoms of this element, like nitrogen, are the older leaves of the plant first. A browning (dead tissue) always found in the older plant leaves first. The first occurs along the leaf margins. As symptoms become more symptom is a loss of sheen or shine of the older leaves severe, the browning progresses into the tissue between the (some report this as a darker green colour). Next the area leaf veins, and to younger leaves. Potassium deficiency can along the main veins of the underside of these leaves tends also be expressed in irregular brown spots throughout the to exhibit red, yellow and bluish pigments. This leaves. Potassium deficiency also causes a reduction in colouration eventually spreads to other portions of the plant growth. leaves. The young leaves generally remain green but are reduced in size. Calcium deficiency (Ca) Phosphorus-deficient plants are stunted. Maturity of the Calcium deficiency symptoms are most pronounced in plant is often delayed. Root development is poor. young plant tissue. The emerging leaves produce brownish- black (dead tissue) areas along the leaf margins. The newer or bud leaves are distorted at their tips or bases. This © State of Victoria, Department of Primary Industries Page 1 AG0257 causes later growth to have a cut-out appearance at these Zinc deficiency (Zn) points. As the leaf expands, the surfaces can become Disorders caused by zinc deficiency include reduction in puckered because of the injury to the leaf tips. With more leaf size and a shortening of internode lengths. Stem severe calcium deficiency, the new bud tissue or entire growth retardation is thought to be due to the deficiency of growing point may blacken and die. zinc prohibiting sufficient production of the growth hormone, auxin. Interveinal chlorosis (a yellowing of the leaf tissue between the veins) may also occur with zinc deficiency. Manganese deficiency (Mn) Deficiency symptoms first appear on young tissue and are very similar to iron deficiency, except that the persistent band of green along the leaf veins is broader. The interveinal chlorosis (yellowing of leaf tissue between the veins) is not as severe as with iron deficiency and there is little reduction in leaf size associated with this disorder. Severe cases of manganese deficiency symptoms are not Figure 2. This Banksia marginata plant exhibits the symptoms of common in ornamental foliage plants. potassium deficiency-browning along the leaf margin of older leaves. As symptoms become more severe the browning will Boron deficiency (B) progress into tissue between the leaf veins. Plant stems become thickened, tough and brittle and internode length is reduced, when a plant is deficient in Magnesium deficiency (Mg) boron. Other symptoms include the young leaves at the The symptom of magnesium deficiency occurs in the older terminal bud becoming light green at the base, which leaves first and then is exhibited in the middle leaves of the breaks down and causes leaves to become twisted in later plant. A bronze yellow colouring occurs in a V-shape and growth. the tongue of tissue along the midvein, towards the base of the leaf, usually remains green. This is a distinctive Iron Deficiency symptom of magnesium deficiency. In some cases these Iron deficiency (Fe), or lime-induced chlorosis, is often leaves may redden or develop dead areas along the leaf caused by an alkaline soil (high pH). As the pH of the soil margin or between the veins. increases above 6.0, the availability of iron to the plant gradually decreases. Sulphur deficiency (S) A wide range of ornamentals including both Australian Commercially sulphur deficiency is seldom a problem in native plant species and introduced species is affected by plant production. Whilst most soils contain sufficient iron chlorosis (see Table). sulphate, "soilless" potting media usually have a fertiliser such as ammonium sulphate or potassium sulphate added, Importance of iron in which case the sulphate is a "carrier" for another Iron is needed by all plants. It is an essential precursor for element. the formation of chlorophyll, which gives plant foliage its Sulphur deficiency causes the younger leaves of the plant green colour. Chlorophyll is an active element in to become pale green in colour, particularly between the photosynthesis, a process which allows the plant to grow, leaf veins. mature and produce flowers. Iron is also important for normal activity of enzymes involved in plant respiration. Molybdenum deficiency (Mo) Symptoms of iron deficiency Inadequate molybdenum causes yellowing between the leaf Plant growth and vigour are reduced when the iron supply veins; the older or mid-stem leaves are the first to be is limited. Since iron is not easily translocated within the affected. Sometimes a disorder commonly known as plant, the symptoms of reduced green colour, due to less "whiptail" may occur. In this case the plants may develop chlorophyll production, appear on the new leaves. The severely twisted young leaves, which eventually die. visual symptom on these new leaves is interveinal chlorosis, or yellowing of the plant between the leaf veins Copper deficiency (Cu) (see Figure 3). In severe cases the entire leaf may be white. Plants suffering from copper deficiency are severely This symptom is similar to that caused by magnesium stunted with exceedingly small terminal leaves (often only deficiency but iron deficiency is exhibited on the younger one fifth or less of normal size). Terminal leaves leaves, while magnesium deficiency is exhibited on the eventually die and multiple budding occurs immediately older leaves. Symptoms of iron deficiency tend to be more below the dead terminal. These buds will also die pronounced during winter. terminally and often multiple buds will develop on each break giving the plant a "witches broom" appearance. © State of Victoria, Department of Primary Industries Page 2 AG0257 Causes of iron deficiency Iron deficiency does not only occur in alkaline soils but very often develops in acid soils, frequently limiting the growth of such acid-loving species as azaleas and rhododendrons. This condition may result from an accumulation of the heavy metals, copper, manganese and zinc, relative to the amount of iron present. Other factors, which may cause iron to become unavailable for plant use, are: • high levels of calcium and magnesium carbonate • overwatering of plants, causing poor aeration • high or low temperature Figure 3. Symptoms of iron deficiency include interveinal • root damage chlorosis of the young leaves, as exhibited by the Eucalyptus • large amounts of bicarbonate ions in soil solution or leucoxylon plant above. irrigation water Table 1. Some of the plants commonly affected by iron • high nitrate nitrogen in fertilisers chlorosis • high phosphate levels Introduced species Australian native • a deficiency of iron itself. species Control Azaleas (Azalea indica) Acacia Iron deficiency causes plants to be less vigorous, less Camellia (Camellia japonica) Banksia (e.g. Banksia attractive and less saleable. To alleviate the problem of Cyclamen (Cyclamen persicum) ericifolia) Gerbera (Gerbera x jamesonii) Crowea (e.g. Crowea iron deficiency in a soilless potting media, one of the Hydrangea (Hydrangea exalata) following programmes may be useful. macrophylla) Dampiera • Short term crops (including many indoor plants) crop Magnolia (Magnolia x Eucalyptus (e.g. life of 3 - 5 months. soulangeana) Eucalyptus gunnii) Petunia (Petunia hybrida) Eriostemon (e.g. (a) 0.5 kg/cubic metre ferrous sulphate 0.5 kg/cubic metre Rhododendron Eriostemon "Micromax" or Rose (Rosa) myoporoides) (b) 0.2-0.4 kg/cubic metre "Sequestrene 138" iron chelate. Gloxinia (Sinningia hybriden) Grevillea (e.g. Grevillea Since there is only a small amount of iron sulphate, in Piggyback plant (Tolmeia rosmarinifolia) "Micromax", it is important to add extra iron in option (a) menzesii) Hypocalymma Blueberry (Vaccinium) Prostanthera in the form of ferrous sulphate. The iron in ferrous sulphate is not available to the plant for a long period of time since Chlorine deficiency (Cl) it is easily leached from the potting mix or complexed by Chlorine is rarely, if ever, deficient in plants growing in phosphate to form insoluble iron phosphates. nature because of its high solubility and availability in soils Option (b) provides available iron for the plant over a and because it is also transported in dust or in tiny moisture much longer period of time than option (a).