Dr. Phyto

French marigold

Tagetes patula

Diseases & pests on this plant

• marigold leaf & flower blight (Alternaria)Alternaria tagetica

  Dark brown to black spots, often with concentric rings and a yellow halo, appear on the lower leaves first and enlarge until the leaf shrivels; the blight runs up the stem and into the flower buds and petals, which rot and turn brown. Worst in warm, wet, humid weather and on crowded plants.

• slugs & snailsGastropoda

  Irregular holes with smooth (not jagged) edges eaten from leaves, flowers and soft stems, often starting at the margins; whole seedlings can vanish overnight; tender hostas, lettuces and bedding are stripped; the tell-tale sign is a silvery dried slime trail on leaves, soil and pots. Damage is worst at night and in mild, wet weather.

• grey mould (Botrytis)Botrytis cinerea

  Fuzzy grey mould on leaves and stems.

• two-spotted spider miteTetranychus urticae

  Yellow stippling on upper leaf surface, fine webbing.

• sclerotinia stem rotSclerotinia sclerotiorum

  White cottony growth on stems at flowering height, stems split open to show black sclerotia (1–5 mm) embedded in pith, premature ripening of affected plants.