Some varieties of lupines are very susceptible to Lupine anthracnose, caused by the fungus Colletotrichum gloeosporioides. On young seedlings, tips begin to die back forming a shepherd's crook. Leaf blights that start with a half-circular brown spot at the edge of the leaf can develop into stem cankers. Severe losses can occur on both seedlings and mature plants ready for sale. Fungal spores are spread by water splashed from overhead irrigation or rainfall.
Remove infected plants and discard. Drench adjacent plants with a fungicide. Champ, Champion, Kocide, KOP-Hydroxide, Bayleton,Cygnus, Eagle, Fosphite, Heritage, Systhane, and Manzate 80 WP are registered for outdoor ornamentals and Colletotrichum diseases. Start with healthy transplants in a well drained soil, provide balanced nutrition, and avoid over-watering. Grow plants on raised benches to prevent contamination from native soil and start with sanitized pots, flats, and benches.