Collecting of plant samples:
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. 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
non representative or incomplete specimens (roots, stems, and soil) are accompanied
by insufficient information, accurate diagnosis becomes impossible. Following are general guidelines for collecting plant samples.
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 laboratory.
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 to send a soil sample. Fill out the Nematode Soil Sample