Yellowish spots on leaf tops, grey coating underneath

Editorial diagnosis

Diagnosis overview

Yellowish spots on leaf tops, grey coating underneath is a visible plant sign, not a diagnosis on its own. The affected plant part, distribution of the pattern, and its progression help narrow down the possible causes.

The symptom is documented in the available plant profiles for crops including Leafy Goosefoot, marjoram, Radicchio. Also check weather, watering, soil moisture, and any changes appearing at the same time.

Compare healthy and affected plants directly and record whether young or old leaves, individual shoots, or the whole plant are affected first. Photos taken several days apart can also show whether the pattern is progressing or remains stable.

A common diagnostic mistake is to assign one visible sign immediately to a specific deficiency, pest, or pathogen. Compare several plausible causes before fertilising or treating the plant.