Dr. Phyto

delphinium (larkspur)

Delphinium elatum

Diseases & pests on this plant

• powdery mildew (ornamentals)Golovinomyces sp.

  A white-to-grey powdery coating spreads over the upper leaf surface, shoots and flower buds; under it the tissue yellows, and young leaves may pucker, curl or be stunted; severe attacks brown and shrivel the leaves. Unlike downy mildew the growth is on the UPPER surface and rubs off; worst in warm days with cool, humid nights and crowded, shaded 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.

• bacterial blight / canker (multi-host)Pseudomonas syringae pv. syringae

  Brown-black angular leaf spots with yellow halos, blackened buds + young shoots that fail to open, sunken brown cankers on stems with bacterial ooze in spring, blossom blight in cool wet bloom periods, branch dieback in heavy infections.

• 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.