Disease Control in the Landscape

Bulletin 614

Chapter 3

Using the Plant and Pest Diagnostic Clinic at The Ohio State University

The C. Wayne Ellett Plant and Pest Diagnostic Clinic (PPDC) is located at The Ohio State University in Columbus, Ohio. It is a comprehensive clinic in that it integrates the disciplines of plant pathology, entomology, crop science, horticulture, and natural resources into a comprehensive program centered on plant disease and pest identification. Services available through PPDC include plant disease diagnosis, insect and mite identification, plant and weed identification, and nematode extractions.

The accuracy of any diagnosis depends upon the information supplied, the specimen material selected, and the condition of the specimen when it arrives.

Specimen Information

PPDC specimen forms are available through county Extension agents or at the clinic. To make best use of the forms:

1. Complete a form for each specimen. Materials that are part of the same problem will be considered as one specimen. Different kinds of plants or plants from different sites usually have different problems and should be considered as different specimens.

2. Describe symptoms as you observe them on the plant or in the planting. After a specimen is packaged and shipped, many of the original symptoms may be obscured.

3. Send the completed form along with the specimen, either inside the package or in an envelope attached to the outside of the package. Make sure that the record form and other enclosures are separated from the specimen material by a waterproof barrier if needed.

Selecting Specimen Material

Select material showing the symptoms in question. Send several samples in different stages of disease development. Be generous, but do not send totally rotten or decayed material, plants that are completely dead, or material that has been dead a long time.

1. Send entire plants, including roots if possible. Dig plants to keep roots intact. Do not pull them out of the ground. Remove excess soil from the roots by shaking gently or washing with water. Do not wet leaves or stems. Wrap roots so that soil clinging to roots will not be loose in the package. Do not ship wet plants.

2. When entire plants cannot be shipped, include the part showing symptoms. Also, include one pint of roots, soil, and fine rootlets.

3. When only localized parts of plants are affected (leaf spots, stem cankers, or swellings), ship several examples of the affected parts. Stem and branch sections should include a short section of healthy tissue so that the transition area between diseased and healthy tissue is included.

4. If oak wilt, Dutch elm disease, or Verticillium wilt are suspected, select samples from branches with wilted, yellow, or dying leaves. Do not select samples that are completely dead. Cut several sections 6 inches long and one-half to 1 inch in diameter.

Packaging and Delivery of Specimens

Careful packaging and quick delivery of the specimens is essential. Please follow these suggestions:

1. Select specimens fresh from the field. Carefully shake off dew or excess water and allow to air-dry before packing.

2. Press non-woody plants or leaves on small branches between paper and place between two pieces of stiff cardboard. Place the sample in a padded envelope.

3. Soft, succulent plants that are packed in airtight plastic frequently decay before their arrival. Package these plants so they may "breathe." Place leaves between dry paper towels before packing.

4. For mailing, use strong containers such as corrugated boxes or mailing tubes that will not crush in transit.

5. Fill empty spaces in mailing cartons with crushed or shredded paper to protect the specimen.

6. Use overnight mail services or mail packages early in the week to avoid weekend layovers at the post office.