The combination of an Australian species of scale insect, Eriococcus orariensis Hoy,and the fungus Capnodium walteri is known as manuka blight (Mulcock, 1954). This relationship of fungus and scale insect killed areas of Leptospermum scoparium in Canterbury, and infested plant material was subsequently distributed in many parts of the North Island in attempts to control Leptospermum in pastures, but Eriococcus orariensis never became established in heavy enough infestation to kill the Leptospermum. An endemic fungus species, Angatia thwaites (Petch) von Arx (syn. Myriangium thwaites Petch), attacked the scale insect and restricted its establishment (Hoy, 1961). Leptospermum ericoides has proved to be resistant to Eriococcus orariensis.

Type: Sooty Moulds and Similar Fungi; Description: Subiculum superficial, floccose, black; on branches, twigs, and leaves. Mycelium composed of dark brown, smooth, moniliform hyphae, up to 15 μm wide. Ascomata perithecial, dark brown, globose, 0.1 mm in diameter. Asci obclavate. Ascospores clavate, 2–5-septate (mainly 3-septate), 20–28 × 6–11 μm, dark green-brown. Conidiomata pycnidial, scattered or in small groups, partly immersed, ampulliform, 0.1 mm in diameter. Conidia fusiform, slightly curved, 7–13-septate (mainly 9-septate), 21–36 × 3–4 μm, golden brown.

Distribution: Northland, Auckland, Bay of Plenty, Taupo, Mid Canterbury.; 1st Record: Mulcock (1954).

Significance: This sooty mould is a highly visible, but non-parasitic, partner in the disease complex known as ‘manuka blight’. The parasitic partner and the principal villain responsible for damage to the plant is the introduced scale insect Eriococcus orariensis Hoy (Eriococcidae), which can be found all parts of the host plant but is generally more numerous on the stem where the flaky bark affords protection. ‘Honey dew’ exuded by the insect is washed down the plant by rainwater. The sooty mould lives on nutrients in the honey dew. If insect infestation is severe the whole plant may become covered with mycelium, giving it a fire-blackened appearance. The first outbreak of the scale insect has been traced back to 1936–37 in the Orari Gorge, South Canterbury (Hoy 1961). By 1950, large areas of Leptospermum scoparium (manuka) in Canterbury had been killed (Mulcock 1954). Although manuka blight had spread to most of the North Island and the eastern side of the South Island by the late 1950s, the amount of damage caused was declining as the insects became parasitised by an endemic fungus, Angatia thwaitesii (Petch) Arx (Hoy 1961). At present, manuka blight is common but rarely severe enough to cause death of the host. Leptospermum scoparium is very susceptible to E. orariensis attack but the closely related Kunzea ericoides (kanuka) is resistant. Capnodium walteri has been reported on Pinus spp. (Gilmour 1966a) but is of no importance.; Host(s): Coprosma lucida, Dracophyllum subulatum, Kunzea ericoides, Leptospermum scoparium, Ozothamnus leptophyllus, Pinus sp.

On living leaves and branches, (1) Cassinia fulvida, Canterbury Prov., Broken River, near Enys, Craigieburn Range, 16. V. 1963, S. J. H., PDD 21313 (DAOM 96214); (2) Dracophyllum subulatum. Auckland Prov., Hatepe, near Lake Taupo, 4. III. 1963, J. M. Dingley, DAOM 96728; (3-5) Leptospermum scoparium, (3) Auckland Prov., Hatepe, near Lake Taupo, 4. III. 1963, J. M. D. & S. J. H., PDD 21329 (DAOM 96215): (4) Auckland Prov., Cossy's Creek Dam, Hunua, 12. 11. 1963, J. M. D., DAOM 160054; (5) North Auckland, Waipu, 21. VI. 1963, J. M. D., PDD 212 2 (DAOM 96218).
Collections (1) and (5) bear Capnodium ascostromata as well as the Phaeoxyphiella pyenidia; the others bear ceratopycnidia only. Ascostromata and ceratopycnidia have also been seen on two collections from New Zealand, preserved in Herb. K,-(a) ' Antennaria robinsonii. New Zealand [scr. M. C. Cooke]. 273. On Cassinia, Te Karaka [scr. presumably T. Kirk]', and (b) 'Antennaria robinsonii. M. 3645 on Coprosma lucida [scr. M. J. Berkeley: coll. presumably Colenso]'.

Ascospores 3-septate, 21.5-25 5 x 8-10 µm; conidia usually up to 15-septate, 45-81 x 6.3-9.5 µm.
Associated anamorph: Phaeoxyphiella morototom Batista et Ciferri (1963).

This species was illustrated and redescribed from New South Wales by Fraser (1935b) and from Formosa by Yamamoto (1954, 1957). Both authors verified the connection between [Phaeoxyphiella] ceratopycnidia and Capnodium ascostromata by cultural methods. Mulcock (1954) and Hansford (1954) redescribed the fungus from New Zealand and Java respectively. Hughes (1976) illustrated and redescribed the Phaeoxyphiella anamorph and discussed synonymy and earlier accounts. This species is apparently widely distributed: besides collections from New Zealand and New South Wales I have seen others from Western Canada and U.S.A., South Eastern U.S.A., Bahama Islands, Puerto Rico, Jamaica, Brazil, Chile, Corsica and South Africa.
Mulcock (1954) and Hoy (1961) presented information on the association of C. walteri with an insect, which causes a disease of Leptospermum scoparium.