Gilmour (1957b) recorded a resinous disease of roots, a collar rot, and a stem canker of young larch trees in Golden Down, Nelson. Later (1966a) he stated that this condition was associated with Pythium undulatum and Phytophthora cinnamomi. Bassett (1961) found Pythium undulatum in soils from nursery beds from which these trees had been propagated.

Type: Radicicolous Fungi; Description: Colonies on corn meal agar submerged, no aerial mycelium, main hyphae up to 7 μm wide. Chlamydospores present, terminal or intercalary, subglobose, 20–60 μm in diameter, dark yellow, thick walled (2–5 μm). Sporangia terminal, ellipsoidal, 80–160 × 40–60 μm, with an apical papilla, proliferating internally with 1 or more sporangiophores. Oogonia, antheridia, and oospores not known.

Distribution: Wairarapa, Nelson.; 1st Record: Bassett (1961).

Significance: Found to be closely associated with resinosis of roots and lower stems of Larix decidua and L. kaempferi in Golden Downs Forest (Nelson region). This condition was first discovered in 1935, when many 3-year-old trees that had wilted and died were found to be exuding resin from the roots and butts. Between 1935 and 1937 over 4000 diseased trees were pulled up and burnt. In 1950, planting of larch was resumed and the disease again became apparent (see Bassett 1960). The connection between larch resinosis and P. undulatum was established later by Bassett (Rawlings 1962).; Host(s): Larix decidua, L. kaempferi.