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Test, Don't Guess. How to submit plant and insect samples for diagnosis.

Worth the time and money?

Proper diagnosis is essential to managing an insect pest or plant disease. Inappropriate methods—or techniques applied at the wrong time—can waste time and money and might be hazardous to the applicator and the environment. They could even compound a pest problem.

Identification isn’t always easy, even with a specimen in hand. For example, pathogens (disease-causing agents) often have complex life cycles. Once a plant is stressed, secondary agents may take advantage of its weakened condition, masking the presence of the pathogen that initially caused the problem.

The Plant Disease Diagnostic Clinic analyzes plants and soil for pathogenic bacteria, fungi, viruses, and nematodes; the clinic also identifies plants. The Insect Diagnostic Laboratory identifies insects and insect damage (many specimens are pests of plants, animals, stored foods or buildings). Reports usually include pest management suggestions. (For more information about integrated pest management, contact your Cornell Cooperative Extension offices or the NYS IPM Program).

Both clinics strive to identify problems as quickly as possible. In most cases, the laboratories provide results in one to three days by e-mail or fax, or one to two weeks by mail (a written copy is always sent). Of course, some mysteries take longer to solve.

To allow the diagnosticians to do their best work, please follow the guidelines for collecting and shipping all samples, plus the suggestions specific to plant or insect samples. If you have questions, check the website or contact the clinic for advice first.

Both clinics have received problematic submissions. Imagine trying to work with a single insect that’s been crushed into shards, a tomato that’s become juice, or the wrong part of a plant. The diagnosticians are not psychics! The accuracy of their analysis depends on the quality of the sample.

A reasonable guess can be risky...

Yellowing and reduced growth might lead you to suspect a plant disease, but there could be another cause: nematodes. These microscopic worm-like animals feed mainly on plant roots, causing symptoms that mimic plant diseases. In addition, the wounds they inflict predispose plants to infection by pathogens, which further complicates the situation.

Without expert diagnosis, you could try to solve the wrong problem. Would you know to submit a soil sample for nematode analysis–and how to properly collect one?

Hone your sampling expertise to get the most out of our expertise.  Inside are tips about how to collect and submit plant and insect samples.