How To Collect and Package Plant Disease Specimens

The accurate diagnosis of specific plant diseases depends upon several factors. The specimen must arrive at the laboratory in a fresh condition, but just as important, it also must be representative of the symptoms expressed in the field, lawn, or yard. Also, the complete description of the area, its history of cultural or chemical practices, and other facts pertinent to the disease occurrence must be supplied in order to facilitate complete diagnosis of the cause. When specimens arrive in a crushed, wilted condition, or if they are in advanced stages of decay, diagnosis is often difficult. If nonrepresentative or incomplete specimens (roots, stems, and soil) are accompanied by insufficient information, accurate diagnosis becomes impossible.

Leaf Spots

  1. Collect leaves showing all stages of infection. Make sure compound leaves are collected with leaflets attached to petioles. Also include twig segments with leaf samples.
  2. Use the plant press to transport from field to office. Once ready to ship (within 24 hours), place the leaves between heavy paper or thin cardboard and place them in an envelope. They will arrive in a pressed state, making processing easier.

Galls or Cankers

  1. Select several galls along with small portions of twigs or limbs if possible. Include intact leaves if possible.
  2. Make sure you include healthy portions of the plant.

Wilts

  1. Send whole plants when possible. Collect several plants, showing all stages of the disease.
  2. Dig the plants; do not pull them up. Include a small amount of soil with root system. Keep soil and aboveground plant parts separate by placing roots in a plastic bag and sealing with a rubber band. Do not add moisture to the root sample.
  3. Send a soil sample along with the plant. Use the Nematode Soil Sample bag (Form 591) to send a soil sample. Fill out the Nematode Soil Sample Form (Form 448A).

Fruits and Fleshy Organs

  1. Do not send specimens of advanced stages of fruit rot. Select plants showing early to intermediate symptoms.
  2. Keep specimens cool until shipped. Wrap several sheets of dry paper towel around the fruit. Do not add moisture. Pack specimens so that they are not crushed during shipping.

Turfgrass Samples

Turfgrass samples should be taken from the edge of the affected area and include both dying and healthy plants. Collect several 3by3inch squares of sod with at least 1 inch of soil. Place these in sealed plastic bags.

Packaging and Mailing

Samples submitted to the diagnostic lab should be accompanied by a check in the amount of $6 made payable to Extension Plant Pathology.

  1. When mailing plant specimens for disease diagnosis, wrap a dry paper towel around the specimen and place it in a zipperseal plastic bag. The purpose of the paper towel is to absorb any moisture released from the plant tissue, thus avoiding bacterial soft rot prior to arriving in the laboratory.
  2. Use regular mailing envelopes whenever possible to save money on postal fees.
  3. Mail early in the week, and be sure to mark the package “First Class.” This will allow us to get the sample as fast as possible and it will be less likely to spend the weekend in the post office.
  1. Fill out the Plant Disease Diagnosis and Insect Identification Form (Form 205) as completely as possible, or have the grower fill it out. The extra five or ten minutes it might take to fill out the form could save us an hour or more of “barking up the wrong tree” when examining the specimen in the lab.
  2. Make sure packages are wrapped in heavy paper. Mail samples to:

Extension Plant Pathology/Nematology Lab 190 Bost North, Room 9 Mississippi State, MS 397629655

Copyright 2007 by Mississippi State University. All rights reserved. This publication may be copied and distributed without alteration for nonprofit educational purposes provided that credit is given to the Mississippi State University Extension Service.

By David M. Ingram, Extension/Research Professor, Plant Pathology.

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Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. MELISSA J. MIXON, Interim Director (POD1007)