Keeping Native Plants Healthy

Iron deficiency is a very common disorder in native plants and examples may be found in most gardens which contain a reasonable selection of Australian plants.
Iron deficiency is easily recognised by a yellowing of the new shoots, accompanied by a slowing down in the rate of growth. If the plant is not treated, the yellowing may extend further back down the stem and eventually
the plant may become completely yellow and stop growing altogether.
Iron deficiency symptoms can result for a number of reasons, the most common being:

Alkaline soils
Alkaline soils tie up iron and render it unavailable to plants. Often plants close to concrete or brickwork suffer from iron deficiency because lime leaches out of the mortar and creates localised alkaline ‘ hot spots’ .

Poor drainage
Waterlogging renders iron unavailable to plants. This can be an important factor for plants in pots where drainage holes may be impeded or where a good quality potting mix is not being used.

Excessive levels of other elements
This is unlikely to occur in the garden but is a common reason for iron deficiency symptoms in potted plants where the plants have been fed too heavily with fertilisers, particularly phosphorus.

Treatment
Iron deficiency is easily treated with an application of iron chelates, which is applied through a spray pack or watering can, onto affected foliage. Apply a thorough coverage as only those parts of the plant sprayed will green up. The foliage should start to green up within two weeks, although one or two repeated applications may be necessary. Applying iron to the soil is unnecessary and generally wasted, as the iron is quickly transformed into a state where it is rendered unavailable to the roots of plants.

Commonly affected plants.
While iron deficiency symptoms have been observed in almost every Australian plant genus, the following plant groups have shown themselves to be particularly frequent offenders.

Baekia
Banksia
Boronia
Brachysema
Calytrix
Chamaelaucium
Correa
Crowea
Darwinia
Dilwynia
Eriostemon
Eutaxia
Grevillea
Hakea
Hibbertia
Hovea
Hypocalymma
Persoonia
Phebelium
Pultenaea
Thryptomene

Further information
Talk to your local Garden Centre about caring for your
native plants and garden.

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