Tomatoes are a favorite vegetable crop in Kentucky gardens. However, this staple of the home garden often falls victim to diseases, insect pests, or abiotic conditions, such as poor site characteristics and planting practices, mechanical damage, chemical damage, etc. When problems arise, the two questions on gardeners’ minds are:
- What caused the problem?
- What can be done about it?
The first step toward answering these questions may be contacting the local county Extension office. An Extension agent may be able to quickly diagnose the problem, or if not, can then assist in preparing plant samples for submission to the University of Kentucky Plant Disease Diagnostic Laboratory.
Selection and packaging of a sample might sound straightforward, but a few common mistakes can result in an “insufficient sample” response and delays in determining the cause of problems. The tips below can lead to a more timely and accurate diagnosis of tomato problems, as well as problems on other vegetable or herbaceous crops. These guidelines are appropriate for commercially produced crops, as well as home garden samples.
Tomato Sample Submission
- When possible, submit the entire plant including roots. Dry packing material should be used to pad the sample and reduce damage during shipping. Wrap the rootball in a plastic bag, leaving leaves and stems exposed; this also keeps foliage from becoming contaminated with soil from the rootball (Figure 1)
- In the event that a whole plant cannot be sent as a sample, provide the portion of the plant that appears to be affected along with healthy tissue for comparison.
- When symptoms are present on tomato fruit grown in the garden, an entire plant with fruit may be submitted. If only tomato fruit are to be submitted for diagnosis, then each tomato should be wrapped in several layers of dry newspaper. The box should be packed with several layers of extra padding to avoid damage during shipping (Figure 2). Do not seal fruit in plastic bags. If fruits are softening or becoming “leaky,” these samples may not be useable for diagnosis if deterioration is severe.
- Provide detailed information, such as plant age, variety, planting site, and symptoms. This information is often as important as the physical material collected. Provide as much information as possible on the Plant Disease Identification Form submitted with samples (Figure 3). Enclose forms in a plastic bag to protect them from soil and plant debris during shipping. In some cases, photos of entire planting and surrounding sample area may be submitted by the Extension agent.
- Submitting Plant Specimens for Disease Diagnosis (PPFS-GEN-09)
- Plant Pathology Publications (Website)
Kimberly Leonberger, Plant Pathology Extension Associate; Julie Beale, Diagnostician; Brenda Kennedy, Diagnostician; and Emily Pfeufer, Extension Plant Pathologist