P&PDL Picture of the Week for
April 6, 2009

Symptoms of Iron Deficiency

Roberto G. Lopez, Ph.D., Assistant Professor & Floriculture Extension Specialist, Purdue University

Symptoms of iron (Fe) deficiency typically appear as interveinal leaf chlorosis (Figure 1) on shoot tips and then progress throughout the entire plant.  In extreme case, the leaves of some plants will turn almost white (Figures 2 and 3).  Fe deficiency can be prevented by controlling pH and alkalinity and using an iron chelate fertilizer.  Irrigation water with high alkalinity (commonly found in the Midwest) typically has a high pH.  Many micronutrients, including Fe, are not available to plants when the root zone pH is high. The acceptable pH range for plants that are susceptible to iron deficiency such as calibrachoa, pansy, petunia, scaevola, snapdragon (Figure 4), and sutera is between 5.5 to 5.8.  Growers can lower substrate pH by acid injection. They can also apply iron sulfate or iron chelates such as Sprint 330® (10% iron) or Sprint 138® (6% iron) to "green up" plants quickly.

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Iron deficiency in petunia

Figure 1. Petunia with interveinal chlorosis due to high pH.

Iron deficiency in calibrocha

Figure 2. The yellow to white foliage in this calibrachoa is an iron deficiency due to high substrate pH.

Iron

Figure 3. Iron deficiency in Northern sea oats (Chasmanthium latifolium).

Iron deficiency in snapdragon

Figure 4. Iron deficiency in snapdragon.

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service