Agriculture & Natural Resources

UD Plant Diagnostic Clinic

The Plant Diagnostic Clinic at the University of Delaware accepts plant samples showing signs or symptoms of disease. The Clinic is housed in the Department of Plant and Soil Sciences at the University of Delaware in Newark , and operates as a function of Delaware Cooperative Extension. Plant pathology is the study of plant disease and the control of plant diseases.

The UD Plant Diagnostic Clinic is a part of  the National Plant Diagnostic Network (NPDN). The mission of the network is to enhance national agricultural security by quickly detecting introduced pests and pathogens. This system links diagnostic laboratories with common strategies and tools, and increases communication among plant pathologists and the public.

Click here for the Delaware Plant Diagnostic Form Nov2014 (click blue type to download) that should accompany any sample, with information filled in as completely as possible. A copy of the sample submission form may be downloaded and printed from this site. Many homeowner samples may not need to be sent to the Clinic, but may be diagnosed by Master Gardeners or County Agents in the county Extension offices. The Nematode Assay Service is a different fee based service provides identification and enumeration of plant parasitic nematodes in soil and plant tissue (requires Nematode Assay Information Sheet). See the web page:

New! Here are some helpful hints and suggestions to help all of us to accurately and quickly diagnose plant disease and insect samples that come in.

  1. If a sample consists of just one or two leaves of an unknown plant or a dead brown branch, we probably will not be able to tell much.  Please request a new sample from the client.
  2. Samples should be placed in a ziplock plastic bag.  Samples in open plastic bags from grocery stores or paper are usually too dry by the time they get to Newark.
  3. Wet, soft fruits or vegetables should be placed in dry paper towels and then double bagged in case they break down and leak.
  4. Turfgrass samples should contain a margin between healthy and diseased, and should be a section of turf with a bit of soil underneath (4 x 4 inches is good). Plastic containers such as butter tubs or for left-overs work well as containers.
  5. Anything sprayed with a pesticide should not be sampled and sent for at least 24 hours.
  6. Insect identifications can be made from plants, household, or foundation habitats.  Anything from a human body is not appropriate to send to Newark, and should be sent to the Department of Health.
  7. Information filled in on the forms can be very helpful. Remember, this work is like doing a jigsaw puzzle.  The more pieces we have, the easier it is to complete!