Tomato Leaf Mold in Greenhouses: What to Photograph and Record
Turn the leaf over. Pale yellow patches on the upper side of a greenhouse tomato leaf tell only part of the story. Olive-brown, velvety growth beneath those patches makes tomato leaf mold a possibility worth investigating.
Leaf mold often starts on older leaves. It is associated with greenhouse and high-tunnel production, where humid conditions favor disease. The University of Minnesota leaf mold guide includes photographs of both leaf surfaces.
Photograph both surfaces
Begin with a view of the plant in its row. Show where affected leaves sit in the canopy. Then photograph the upper surface of an affected leaf and the underside of the same leaf.
Keep the leaf in focus and avoid a bright reflection that hides its surface. Include a less affected leaf for comparison. If you use a fixed camera, remember that it can repeatedly miss the underside, even when its images look sharp.
The header illustration is decorative. Use the extension photographs and an actual plant examination to compare symptoms.
Treat humidity as context
Minnesota Extension reports that relative humidity at or above 85% favors severe leaf mold outbreaks. Disease can also occur below that level. A sensor reading therefore cannot confirm leaf mold or rule it out. The fungus that causes the disease is Passalora fulva.
Save the sensor location with its readings. A measurement near a doorway describes that location. It does not automatically describe the air around a crowded lower leaf.
A useful observation record links three things:
| Record | What to include |
|---|---|
| Plant observation | Plant or row identifier, date, affected leaf position, and visible changes |
| Photo | Whole plant, upper leaf surface, and the corresponding underside |
| Conditions | Sensor location, humidity and temperature history, irrigation, and ventilation changes |
This is a suggested record for your own workflow. PlantLab’s photo request does not accept these sensor readings as diagnosis inputs.
Respond to the conditions and inspect the plants
Review airflow and moisture management while you investigate. Minnesota Extension recommends monitoring for leaf mold during humid periods. Its management guidance also explains why a resistant variety is not protection against every race of the fungus.
For a spreading problem, ask a local extension adviser or plant clinic to help identify the cause. Send the two leaf views and the growing history. Ask about sample handling before removing material for testing.
A yellow patch alone is not enough to choose treatment. Keep any treatment decision separate from a camera alert or a humidity threshold.
Connect photos to a greenhouse workflow
PlantLab supports tomato leaf mold diagnosis. A developer can submit a photo through the plant health API and store the returned request identifier beside the observation record.
Use the result to bring a plant to someone’s attention. For example, a dashboard can show the photo, the returned condition and confidence, and the environmental record together. A person then inspects the plant and decides what to do.
Handle an unsupported or uncertain result explicitly. An empty result does not mean that the greenhouse is healthy. One photo also cannot establish the health of every plant in a row.
For a first trial, sign in and submit a tomato photo. For machine integration, start with the agent quickstart and OpenAPI contract. OpenAPI describes the request and response fields that software can use.