Diagnostic Test Kits

Tomato Spotted Wilt Virus (TSWV) on Tomato Plant
Agdia immunostrip tests. The strip on the left is positive; the one on the right is negative.
Pepper leaves with INSV

On-site test kits have come a long way. Test kits are easy to use and are available for several plant pathogens (viruses, fungi and bacteria) important to floriculture crops. Growers should consider stocking up on a few test kits for the spring growing season. Test kits will confirm your disease diagnosis, allow you to detect diseases early, provide you the option to treat only when necessary, and use the proper management for the disease. As a result you will maintain good crop quality.

Easy to use ImmunoStrips (dip-stick tests) are available from Agdia to detect viruses such as Impatiens Necrotic Spot Virus (INSV), Calibrachoa Mottle Virus (CbMV), Tobacco Mosaic Virus (TMV), Tomato Spotted Wilt Virus (TSWV),and Cucumber Mosaic Virus CMV) to name a few. There is also a combination kit for INSV/TSWV/TMV/CMV. Immunostrips are also available for several important bacterial pathogens such as Xanthomonas campestris pv . pelargonii, Ralstonia solanacearum and Clavibacter michaganensis subsp. michiganensis.

Pocket Diagnostics produces tests for Phytophthora, Ralstonia, and potato virus Y (PVY).

ALERT-LF kits from Neogen Corp. are available for Pythium, Phytophthora, and Rhizoctonia.

How Test Kits Work

Each company's kits are used a little differently, but the same principles apply. Tests are based on antibodies that are designed to recognize antigens specific to each pathogen. Any antigen present in the plant sample is extracted by grinding in the extraction solution. The extracted antigen then reacts with antibodies in the test strip that capture specific antigens when they are present. A dye in the test strip enables the captured antigen to be visualized.

Taking Samples for Testing

Early detection and success using test kits are only as accurate as the sample taken.

For example, if a plant has symptoms of INSV, a quick test will confirm your suspicions. Collect a sample from the part of the plant showing symptoms, including green or chlorotic tissues adjacent to the necrotic area. Do not use plant material that is completely dead. Follow package directions. Using too much plant material can result in false negatives.

Companies That Manufacture Test Kits

Kits need to be refrigerated and expiration dates observed.

ImmunoStrips from Agdia Inc.: http://www.agdia.com

ALERT-LF Kits from Neogen Company:  http://plant.neogeneurope.com

Pocket Diagnostic: https://www.pocketdiagnostic.com

See also: "Western Flower Thrips and Tospovirus" .

Author: 
Tina Smith, UMass Extension (Retired); updated by Angela Madeiras
Last Updated: 
June 2019