Type: Caulicolous Fungi; Description: Conidiomata acervular, often confluent; setae absent; on lesions on stems, leaves, petioles and pods. Conidia cylindrical, straight; apex rounded, base often truncate; 0-septate, 14–17 x 3–4 μm, smooth, hyaline; conidial masses pink, abundant; appressoria irregular in shape.

Distribution: Northland, Auckland, Coromandel, Waikato, Bay of Plenty, Taupo, Gisborne, Hawkes Bay, Taranaki, Rangitikei, Wanganui, Wairarapa, Wellington, Nelson, Marlborough, Mid Canterbury, Dunedin, Southland, Stewart Island.; 1st Record: Williams (1993).

Notes: The fungus causing blight or anthracnose of lupins has been previously identified in New Zealand as Colletotrichum gloeosporioides, based on morphological characters (Dick 1994). However, molecular analyses (Lardner et al. 1999; Guerber et al. 2003) demonstrated that it belongs within C. acutatum sensu lato. Nirenberg et al. (2002) identified the worldwide lupin anthracnose clade as a separate species, C. lupini.

Significance: This fungus is of major significance to forestry as the cause of lupin blight. The fungus infects lupin plants of all ages and all above-ground parts are susceptible to infection. Infected leaves and petioles wither and much of the foliage is cast. Lenticular lesions develop on branches and stems, particularly at branch axils, and branches often break at the site of infection. Formation of cankers at ground level, leading to death of the whole plant, is common. The fungus also infects developing seed pods which become necrotic. In warm and wet weather, pink conidial masses develop on the pods and on lesions. Until the late 1980s, Lupinus arboreus was a successful secondary coloniser of coastal sand dunes, and was an important component of the planting succession used to establish Pinus radiata forests on mobile sand. It provided shelter for the young trees and its ability to fix atmospheric nitrogen increased the nitrogen status of the ecosystem, thus enhancing tree growth and productivity (Mead & Gadgil 1978). Lupin blight was first noticed in 1988 in Woodhill Forest (Auckland). A survey in early 1989 showed that the disease was present in coastal areas throughout the country, from Spirits Bay in the far north to Masons Bay, Stewart Island. Mortality was estimated to be 90–95% in the North Island and the northern half of the South Island and 60–65% in other parts of the South Island (Dick 1994). Loss of most of the lupins from fixed sand dunes means a substantial reduction in the availability of nitrogen to primary stabilising plants and to the forest crop. There is a risk of reversion to drifting sand and reduction in the productivity of sand dune forests unless fertiliser is applied or other nitrogen-fixing plants able to take the place of L. arboreus in the ecosystem are found (Gadgil et al. 1999). The origin of Colletotrichum lupini is not known. The only other records of Colletotrichum on Lupinus spp. from New Zealand are those of C. acutatum and C. acutatum f.sp. pineum on L. arboreus and C. acutatum f.sp. pineum on L. angustifolius. These fungi are morphologically quite distinct from the lupin blight pathogen. The sudden appearance of the fungus suggests that it was a recent introduction.; Host(s): Lupinus angustifolius, L. arboreus, L. cosentinii, L. pubescens.