How to Properly Diagnose Plant Problems

By Nora Catlin|April 2, 2024

Correctly identifying the cause of a problem in your greenhouse crop is the first step in effective and economic management practices. Correct identification prevents costly mistakes such as further spread of a pathogen or insect, or the failure of management methods if a problem is mis- or undiagnosed. For example, you wouldn’t want to treat a nutritional imbalance with a fungicide, or use a pesticide to manage what you think the issue might be when that pesticide will be ineffective for the problem that is actually happening.

In a recent e-GRO alert, Nora Catlin of Cornell University notes that it is good practice to always inspect incoming plants and cuttings and to continue to regularly scout crops. When you notice something is amiss, make sure you get close and really look. You’ll want to look carefully at leaves and stems, flip leaves over, and check out the roots. Taking a look at some symptom-less plants is also a good idea for comparison. Look for any and all signs, symptoms, insects, mites, and so on. Good light and magnification helps.

You should also look for patterns as they usually help tell the story. Remember that something caused by a biological or biotic agent, such as a pathogen or insect, will tend to occur in a random pattern. In a broad view (e.g., on a bench or in a crop), plants with symptoms caused by a biotic agent will generally be scattered and not uniformly occurring. Symptoms caused by an abiotic or non-living cause, such as a nutritional or cultural issue, will have a more uniform or consistent pattern.

For more tips and advice from Catlin, check out the original e-GRO alert here.