An Iodine-Based Starch Test to Assist in Selecting Leaves for HLB Testing

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Material Information

Title:
An Iodine-Based Starch Test to Assist in Selecting Leaves for HLB Testing
Physical Description:
Fact sheet
Creator:
Etxeberria, Ed
Publisher:
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication:
Gainesville, Fla.
Publication Date:

Notes

Acquisition:
Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status:
Published
General Note:
"Original publication date December 2007. Reviewed February 2011."
General Note:
"HS1122"

Record Information

Source Institution:
University of Florida Institutional Repository
Holding Location:
University of Florida
Rights Management:
All rights reserved by the submitter.
System ID:
IR00004230:00001


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Ed Etxeberria, Pedro Gonzalez*, William Dawson and Timothy Spann2

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An Iodine-Based Starch Test to Assist in Selecting Leaves for HLB Testing 2Figure 1. [Type a quote from the document or the summary of an interesting point. You can position the text box anywhere in the document. Use the Text Box Tools tab to change the formatting of the pull quote text box.] A. B. C. D. Figure 1. Citrus leaves showing HLB symptoms (A), m anganese (B), zinc (C) and iron (D) deficiency symptoms. Photo credits: Tim Spann (A) and Tom Obre za (B, C, and D), University of Florida.

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An Iodine-Based Starch Test to Assist in Selecting Leaves for HLB Testing 3 Iodine solutions commercially available at most pharmacies and drugstores Betadine, Xenodine or generic equivalent Povidone-Iodine 10% (PVP) No Iodine tincture USP Iodine 2% (may or may not also include sodium iodide 2.4%) Yes Lugol's iodine* Iodine 2%, potassium iodide 4% Untested, but should react *This is a dietary supplement sold to alleviate iodine deficiency in humans, and thus is expensive and impractical to use for this test. not entire cut surface (Figure 4). Nutrient-deficient leaves generally stain similar to a healthy green leaf (Figure 5). ureA citrus leaf with the vein corking symptom of HLB properly sectioned for the iodine test. The arrow indicates the symptomatic section to be used for testing.

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An Iodine-Based Starch Test to Assist in Selecting Leaves for HLB Testing 4 Figure 3. A healthy citrus leaf will show no (A) or very little (B) staining after immersion in the iodine solution for 2 minutes. Note how the staining that does oc cur in a healthy leaf (B) is limited to a couple of cell layers along the leaf surface (arrow). A. Healthy B. Healthy Figure 3. A healthy citrus leaf will show no (A) or very little (B) staining after immersion in the iodine solution for 2 minutes. Note how the staining that does oc cur in a healthy leaf (B) is limited to a couple of cell layers along the leaf surface (arrow). A leaf that showed strong blotchy mottle symptoms of HLB infection stains very dark grey to black along cut surfaces when immersed in iodine solution for 2 minutes. Note that all cell layers of the leaf are stained unlike in a healthy leaf (see Figure 3B). Upper leaf surface

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Figure 5. Leaves showing various yellowing symptoms, not typical of HLB, probably due to nutrient deficiency (A) do not stain darkly whe n immersed in iodine solution (B), indicating that thes e would not be good samples to submit for PCR analysis. A. B. does not not An Iodine-Based Starch Test to Assist in Selecting Leaves for HLB Testing 5 Phytophthora does not