When the most beloved landscape or garden plant begins to show symptoms of a problem, or commercial crops start to decline, panic may set in. The two things on everyone’s mind: what is the cause of the problem and what can be done about it? Since disease is often the prime suspect, the first step for many homeowners and growers is to contact the county Extension office. An agent may then assist in preparing a sample to submit to a University of Kentucky Plant Disease Diagnostic Laboratory.
Selection and packaging of a sample sounds like a straightforward and easy concept…put part of the affected plant in a box or envelope and send it away, right? Wrong! Sample quality and care in packaging can make the difference between receiving a rapid diagnostic report and receiving one of those dreaded “insufficient sample” replies. Avoiding common sample submission errors can result in more timely and accurate diagnoses.
Common Sample Submission Errors
1. Avoid packaging fruit or vegetable samples in sealed plastic bags, which promote decay; no diagnosis can be determined from rotted material (Figure 1). Wrap fruit or vegetables in several layers of newspaper and with extra padding to avoid damage during shipping (Figure 2).
2. Samples submitted with little or no packing material are often further damaged during shipping (Figure 3). Differentiation between symptoms and shipping damage can complicate diagnosis. Wrap rootballs in a plastic bag, leaving leaves and stems exposed; this also keeps foliage from becoming contaminated with soil from the rootball. Use an appropriate sized box that can be padded and secured (Figure 4).
3. Dead is too late. Samples that contain only dead material are often impossible to accurately diagnose (Figure 5). Once a plant has died, secondary pathogens and other organisms invade tissues, complicating diagnosis and making it difficult to isolate the primary pathogen. The best samples include dead, dying, and healthy plant tissues (Figure 6).
4. Providing insufficient information can also hinder a diagnosis. Details about the plant, planting site, and symptoms can be as important as the physical material collected. Provide as much information as possible on the diagnostic forms submitted with samples (Figure 7).
- Submitting Plant Specimens for Disease Diagnosis (PPFS-GEN-09)
- Plant Pathology Publications (Website)
By Kimberly Leonberger, Extension Associate; Julie Beale, Diagnostician; Brenda Kennedy, Diagnostician; and Nicole Ward Gauthier, Extension Plant Pathologist