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NC State Extension

Diagnostic Samples

This is an Extension project to support efforts by Cooperative Extension agents to diagnose specific crop nutritional or disease problems. This project fund a limited number of samples to be submitted by Cooperative Extension agents for analysis at the N.C. Department of Agriculture and Consumer Services Agronomic Division plant tissue or nematode lab, and at the NC State University Plant Disease & Insect Clinic.

When a problem is detected in the field, attempt diagnosis based only upon visual symptoms can be misleading. Problem diagnosis is an important tool that cooperative extension agents use in advising producers to select appropriate corrective management approaches.


  • Pull a soil sample from the problematic area and another from an adjacent spot with normal plant growth. This will permit a comparison between them. Sometimes the problem can be stratified in the soil profile, as high acidity or salt injury. In this case, separate samples should be taken from the surface soil (0-4 inches depth) and subsoil (4 – 8 inches depth). However, for most of the cases, samples from the 0 to 8 inches depth are sufficient for a reliable diagnostic. Fill out the form for soil fertility diagnostic samples to NCDA&CS.
  • Collect tissue samples from the affected plants and from plants of an adjacent spot with normal growth. This will permit a comparison between them. See specific procedures and forms for diagnostic tissue samples to NCDA&CS. For nematode samples, the paperwork is on the Submitting Samples for Problem Diagnosis page.
  • ***IMPORTANT*** All samples need to be identified with the name “Extension Diagnosis” and informing the escrow account number “301600”. Without this identification, it is not possible to use the budget from the Extension Diagnosis project.
  • When sending diagnostic samples, please send an email to Luke Gatiboni ( informing the number of samples submitted.

Written By

Luke Gatiboni, N.C. Cooperative ExtensionDr. Luke GatiboniExtension Soil Fertility Specialist and Assistant Professor Call Dr. Luke Email Dr. Luke Crop & Soil Sciences
NC State Extension, NC State University
Page Last Updated: 9 months ago
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