Why Are There Spots on My Beetroot Leaves?

Discrete spots or lesions on beetroot leaves — usually appearing from midsummer onward — are most commonly caused by Cercospora leaf spot (Cercospora beticola) or Ramularia leaf spot (Ramularia beticola). Both are fungal diseases that produce characteristic spots in warm, humid conditions. On their own, leaf spot diseases rarely kill the plant or prevent root development, but in severe cases they cause significant defoliation that slows root growth. Identifying which disease is present is straightforward from the spot appearance.

Cercospora leaf spot — tan centres with purple borders

Cercospora beticola produces the most distinctive spots of any beetroot disease: small (3–8 mm), roughly circular spots with a tan or pale grey-brown centre and a clearly defined dark purple-red border. In warm, moist conditions (above 20°C with high humidity) the spots are numerous and may coalesce, defoliating entire outer leaves. The fungus overwinters on infected plant debris and reinfects the following season. Remove and bin (do not compost) all beetroot debris at the end of the season; practice crop rotation; choose resistant varieties where available.

Ramularia leaf spot — white centres with yellow halos

Ramularia beticola produces slightly different spots: smaller, with white or pale cream centres and yellowish or pale-brown halos. Like Cercospora, it is most active in warm, humid conditions. In wet summers with warm temperatures, both diseases can be severe enough to cause significant defoliation. Management is the same: remove affected leaves, improve airflow, avoid overhead watering, and clear all debris at the end of the season.

Are the roots usable?

Yes — both Cercospora and Ramularia are leaf pathogens that do not penetrate into the root. Beetroot grown beneath heavily spotted foliage is entirely safe to eat. However, severe defoliation does reduce root development, because leaves are the source of the sugars and carbohydrates that fill the root. Harvest promptly if leaf loss is severe — plants with very little remaining leaf area will not continue developing the root further.