Iron is needed for chlorophyll formation, plant respiration and the formation of some proteins.
- Young leaves first affected
- Yellowing between the small leaf veins, eventually turning almost white
- Fading begins at the leaf margins but progresses interveinally with dead tissue at leaf margins curling upwards
- Leaves may dry and fall
- Often symptoms are seen in only one area of the plant
- Shoots may die back if iron deficiency is not corrected
Often Confused With
Zinc deficiency - interveinal areas turn light green to yellow in mosaic pattern and can become reddish in black and red cultivars while leaf veins become clear with narrow borders of green
Mg deficiency - leaf margins will curl and with severe deficiency the leaves may drop prematurely
Mn deficiency - leaves maintain a normal size and shape
Symptoms first occur on young leaves and in cold, wet soils. Short-term, reversible iron deficiency symptoms may develop in the spring.
Factors associated with iron deficiency include soils with high pH or high magnesium and calcium content, and gross imbalances with other micronutrients like molybdenum, copper or manganese. Deficiency can be caused by high levels of lime in the soil (lime-induced chlorosis). Few soils are deficient in iron but high pH levels restrict availability to the vine. Ensuring good soil structure, aeration and adequate organic matter levels can help make iron more available. Foliar sprays may be used but should be confirmed with tissue analyses before use.