¹ NSW Agriculture, Orange Agricultural Institute, Forest Road, Orange, NSW 2800, Australia.
² NSW Agriculture, Wagga Wagga Agricultural Institute, Private Bag, Wagga Wagga, NSW 2650, Australia.
³ Present address. Agriculture Victoria, Victorian Institute for Dryland Agriculture, Private Bag 260, Horsham, Victoria 3401, Australia.

*alex.nikandrow@agric.nsw.gov.au

Accepted for publication 12/07/01

A root and basal stem rot disease has occurred in narrowleaf lupin (Lupinus angustifolius L.) in New South Wales (NSW) since at least 1993. Leaves of affected plants wilt, become chlorotic and fall. Symptom progression is acropetal and plants die within a few days. Taproots are completely rotted with a dark-brown to black sunken lesion frequently extending up the stem. Symptoms develop usually at pod filling.

In 1999, L. angustifolius cv. Wonga growing in a field trial at Temora, NSW was severely affected by this disease. An undescribed species of Phytophthora was consistently isolated from all symptomatic plants (DAR 75401). The isolates were characterised by non-papillate, ovoid to obpyriform sporangia, nearly spherical oogonia with markedly aplerotic oospores, and amphigynous antheridia. Many of these characters are shared with P. vignae Purss., P. erythroseptica Pethybridge, and the P. megasperma group. However, this fungus also differs significantly from each of these species and is not adequately encompassed by any described species in Erwin & Ribeiro (1996).

The fungus was inoculated into pasteurised potting soil and the pots sown with L. angustifolius cv. Merrit. The plants were grown in a screen house under field temperatures, where they developed typical disease symptoms at flowering to early pod set. Noninoculated controls did not develop disease. The fungus was reisolated from all diseased plants.

A survey of narrowleaf lupins in 2000 showed that this disease was widely distributed in NSW and a Phytophthora identical to the Temora isolates was consistently isolated.

Trapero-Casas et al. (2000) reported a similar disease on three lupin species in Spain caused by P. erythroseptica. Brittlebank & Fish (1927) reported P. cryptogea Pethybridge & Lafferty associated with root rot of Lupinus sp. in an Australian garden, but this is the first report of Phytophthora causing a widespread disease of narrowleaf lupin in Australia.

Brittlebank CC, Fish S, 1927. A Garden Fungus Disease. A Wilt of Tomatoes, Iceland Poppies, and other Garden Plants in Victoria caused by the Fungus Phytophthora cryptogea (Pethy. and Lafferty). Journal of Agriculture, Victoria 25, 380-1.

Erwin DC, Ribeiro OK, 1996. Phytophthora Diseases Worldwide. St Paul, MN:The American Phytopathological Society Press.

Trapero-Casas A, Rodriguez-Tello A, Kaiser WJ, 2000. Lupins, a New Host of Phytophthora erythroseptica. Plant Disease 84, 488.

The British Society for Plant Pathology