Fusarium tumidum Sherb. 1928

New Zealand: COROMANDEL: Coromandel-Whitianga Rd, 2 km from turnoff, coll. P. R. Johnston 166, P. G. Broadhurst, 2 Mar. 1993 (PDD 62184 - holotype; ICMP 11589, 11590); Coromandel-Whitianga Rd, 7 km from turnoff, coll. P. R. Johnston 167, P. G. Broadhurst, 2 Mar. 1993 (PDD 62186; ICMP 11595, 11596,11597); Coromandel-Whitianga Rd, between Matarangi and Kuaotunu, coll. P. R. Johnston 168, P. G. Broadhurst, 2 Mar. 1993 (PDD 62185; ICMP 11602, 11603); Vic. Thames, 8 km along Kauaeranga Valley Rd, coll, P. R. Johnston 163, P. G. Broadhurst, 2 Mar. 1993 (PDD 62183; ICMP 11581, 11582, 11583); Vic. Whitianga, John Riddle's farm, coll. P. R. Johnston G254, 28 Mar. 1992 (PDD 60094; ICMP 11775); Vic. Kuaotunu, Myndermen Rd, coll. P. R. Johnston G249, 29 Mar. 1992 (PDD 60096; ICMP 11773); Vic. Whangapoua, coll. P. R. Johnston 150-2, 29 Mar. 1992 (PDD 60522); WhangapouaCoromandel Rd, coll. P. R. Johnston G248, 29 Mar. 1992 (PDD 60097; ICMP 11554); Coroglen-Whenuakite Rd, coll. P. R. Johnston G252, 28 Mar. 1992 (PDD 60095; ICMP 11774). NORTHLAND: Russell Forest Park, Punaruku Rd, coll. P. R. Johnston G81, S. L. Parkes, 4 Sep. 1991 (ICMP 11763). AUCKLAND: Waitakere Ranges, Huia, coll. P. R. Johnston G46, S. L. Parkes, 27 Aug. 1991 (ICMP 11762; IMI 351950). BAY OF PLENTY: Highway between Katikati and Tauranga, coll. P. R. Johnston G127, S. L. Parkes, 9 Sep. 1991 (ICMP 11764). BULLER: Vic. Reefton, Tawhai Forest, Soldiers Rd., coll. P. R. Johnston G224, G225, 3 Feb. 1992 (PDD 59747; ICMP 11768, 11769); Vic. Reefton, Crushington, coll. P. R. Johnston G221, G222,3 Feb. 1992 (PDD 59748; ICMP 11766, 11767). WESTLAND: Haast Beach, forestry road behind rubbish dump, coll. P. R. Johnston G234, 5 Mar. 1992 (PDD 60162; ICMP 11770); Haast Beach, Track to beach opposite store, coll. P. R. Johnston 140-4, 5 Mar. 1992 (PDD 60134); between Ross and Hokitika, coll. P. R. Johnston G244, G245,6 Mar. 1992 (PDD 61679; ICMP 11771, 11772). CHATHAM ISLANDS: Te Matarae, coll. J. Grindell G212, 3 Nov. 1991 (ICMP 11765).

On Cytisus scoparius

New Zealand: Bay of Plenty: Mamaku Plateau, near summit, coll. E. H. C. McKenzie B84, B86, 12 Dec. 1991 (ICMP 11760, 11761). TAUPO: Kinleath Forest, state highway 30 near junction with state highway 1, coll. P. R. Johnston B47, S. L. Parkes, 10 Sep. 1991 (ICMP 11549; IMI 351951); Vic. Hatepe, coll. P.R. Johnston B51, B52, S. L. Parkes, 10 Sep. 1991 (ICMP 11750, 11757; IMI 351949). Tongariro National Park, vic. Taurewa, coll. P. R. Johnston B57, B58, S. L. Parkes, 10 Sep. 1991 (ICMP 11758, 11759). Buller: Vic. Kumara, coll. P. R. Johnston B97, 3 Feb. 1992 (ICMP 11551).

Description

Perithecia subglobose to broadly pyriform, 200-240 µm wide, 240-260 µm high, nonpapillate, collapsing laterally when dry, dark purple to black, not changing colour in 3 % KOH, becoming red in 100% lactic acid, surface warted, especially near ostiole; solitary or in small groups on small basal stroma; stroma erumpent through host tissue. Perithecial wall 20-40 µm thick (up to 65 µm through warts), comprising cells with 1.5-2 µm thick walls, globose, dark-walled and 10-15 µm diam. near outside, increasingly paler, narrower and more elongate towards the inside, the innermost rows of cells cylindrical, up to 30 x 4 µm, extending to outside of wall near ostiole. Periphyses lining the ostiole in a well-developed layer, cylindrical, 2-3 µm diam. Stroma of similar structure to outside of perithecial wall, comprising hyaline, cylindrical cells up to 25 x 10 µm. Asci 85-100 x 14.5-19 µm, clavate, 8-spored. Ascospores (25-)29-36(-39) x 5.5-7.5(-8.5) µm, cylindrical to elliptical, tapering to rounded ends, curved in side view hyaline, 3(-4)-septate, barely constricted at septa.

Colonies on PDA with white, floccose aerial mycelium, sometimes becoming greyish-yellow with age, usually with abundant orange sporodochia. Undersurface greyish-orange, most cultures also producing distinctive yellowish-brown to brown pigment in agar, Some colonies derived from single ascospores developing dark perithecial initials, but these remaining sterile. Fertile perithecia produced only once in culture using other methods (see discussion). Colony diameter on PDA after 3 d in dark 2.8-4.4 cm at 25 C, and 0.9-2.7 cm at 30 C. Macroconidia on CLA robust, straight to slightly curved, apical cell notched or papillate, basal cell slightly notched to distinctly foot-shaped. Isolates from broom 3-7 septate, 28-80 x 6-10 µm (Figs 7-8), those from gorse 3-12 septate, 30-122 x 6-12.5 µm, occasionally branched (Figs 5-6).

Microconidia absent. Chlamydospores not observed on 4-wk-old CLA cultures.

Latin

Ab. G. pulicaris ascosporis (25-)29-36(-39) x 5.5-7.5 (-8.5) µm differens.

Notes

Gibberella tumida is similar to G. pulicaris (Fr.) Sacc. (anamorph F. sambucinum) and G. cyanogena (Desm.) Sacc. (anamorph F. sulphureum Schltdl.) but can be distinguished by ascosporesize, mostly 29-36 µm x 5.5-7.5 µm for G. tumidum, 20-28 x 6-9 µm for G. pulicaris and 20-25 x 5-7 µm for G. cyanogena (Booth, 1971). Booth (1971) has noted collections of G. pulicaris with larger ascospores, 26-34 x 8-10 µm and although similar to those of G. tumida in length they are different in width. Booth also noted that the wider ascospores of G. pulicaris produce F. sambucinum-type cultures which are not morphologically distinct from those obtained from the smaller-spored forms. The robust macroconidia of G. tumida are quite distinct from those of G. pulicaris and G. cyanogena which have narrower macroconidia measuring (3-)4-5.6(-7) µm and (3.5-)4.5-6(-7) µm in width, respectively (Gerlach & Nirenberg, 1982). Nelson et al. (1983) have placed F. sulphureum in synonomy with F. sambucinum.

Macroconidia of New Zealand material are similar to previously published descriptions and illustrations of F. tumidum (Wollenweber & Reinking, 1935; Gerlach & Nirenberg, 1982; Nelson et al., 1983; Brayford, 1987). The isolates derived from broom had conidia restricted to the lower end of the size range and whilst some isolates from gorse had conidia of similar size to those from broom, most were at the upper end of the range. In all other respects the isolates from broom and gorse were indistinguishable. Between 1% and 5 % of conidia in some isolates were branched (Fig. 5), a feature we have not previously noted in other species of Fusarium. Although chlamydospores were not observed in cultures in this study, Gerlach & Nirenberg (1982) reported them rarely formed by some isolates.

In his description of F. tumidum, Sherbakoff (1928) noted that the fungus resembles F. culmorum (W.G.Sm.) Sacc. but has much larger conidia. The two species can also be distinguished by the relatively slow growth rate of F. tumidum at 25 C, 2.8-4.4 cm after 3 d, compared with 5.5-6.8 cm after 3 d for F. culmorum (Burgess et al., 1988). In addition, F. culmorum usually produces a reddish pigment on PDA (Nelson et al., 1983; von Arx, 1987; Burgess et al., 1988) which has not been reported for F. tumidum and was not observed in any of the isolates examined during this study. A teleomorph has not been reported for F. culmorum.

Fertile perithecia of G. lumida were produced once in culture. Four single ascospore isolates from gorse (ICMP 11582, 11583, 11590, 11597) were grown on petri dishes of corn meat agar with dextrose (Difco). Perithecial initials developed on the culture of ICMP 11590. After 4 wk a suspension was made containing a mixture of conidia from the four culture plates. The mixed suspension was poured over all four plates and excess suspension drained off. Eight weeks later, perithecia with ascospores typical of G. tumida were observed on the ICMP 11590 culture plate. The culture was dried and deposited as PDD 62312.

Fusarium sarcochroum has also been reported from broom and gorse, amongst other hosts (Wollenweber & Reinking, 1935), and from published descriptions appears to develop similar colony pigmentation to that of the isolates of F. tumidum found in New Zealand (Gerlach & Nirenberg, 1982). It was found on dead host plant material associated with a teleomorph described by Wollenweber as Gibberella pseudopulicaris Wollenw. However, sizes reported for the conidia (3-7 septate, 27-63 x 3.7-5.7 µm) and ascospores (3-septate, 18-25 x 5.3-6.5 µm) by Wollenweber & Reinking (1935), clearly distinguish it from the present species. Although Gerlach & Nirenberg (1982) follow Wollenweber & Reinking (1935) in regarding F. sarcochroum as a distinct species in section Lateritium, Brayford (1987) noted that it is not a generally accepted species and Booth (1971) placed it in synonymy with F. sambucinum.

Typification

PDD 62184.