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United States Department of Agriculture

Agricultural Research Service

Trichoderma stromaticum sp. nov., a parasite of the cacao witches broom pathogen
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Samuels, G.J., Pardo-Schultheiss, R.A., Hebbar, K.P., Lumsden, R.D., Bastos, C.N., Costa, J.C., & Bezerra, J.L. Mycol. Res. 104: 760-764 (2000)

T. stromaticum on infected cacao twig

Abstract: A new species, Trichoderma stromaticum, was isolated from 'witches' broom' of cacao (Theobroma cacao) in Brazil caused by Crinipellis perniciosa. The Trichoderma was reported earlier as T. viride and T. polysporum. Trichoderma stromaticum reduced new inoculum through the suppression of basidioma formation. It is characterised by having conidia that slowly become yellow-green in agar culture and by stout, 'Pachybasium-like', phialides formed on the surface of stromatic structures. The closest relations of T. stromaticum are T. harzianum and T. virens. Visit the Trichoderma Identification Aid for an interactive key, images, descriptions, distributions, literature and nomenclature for the genus Trichoderma

Description of the species:

Trichoderma stromaticum Samuels & Pardo-Schultheiss

Type: BRAZIL. PARÁ: BELEM, from dead cocoa broom, C. N. Bastos, TVC, GJS 97-183 (BPI, dry culture. Live cultures: ATCC 204426, CBS 101875. ITS sequence: AF097913).

Optimum temperature for growth: 25 C. Radius of colonies grown on PDA 48 h at 25 C 29 ± 1.1 mm. After 72 h mycelium dense, appressed, off-white, with conidia forming in a dense white shelf around the center and more or less dense broad band around the margin of the colony (dependent on the strain). Conidia white, slowly becoming yellow, green, or yellow-green (3B-E8 or 27C4 and then in the middle of the colony). Radius of colonies grown on SNA after 64 h at 25 C 10.5 ± 2.5 mm. After 72 h aerial mycelium lacking, conidia formed abundantly in 1--3 mm diam., pulvinate to hemispherical pustules. Conidia grey-green (27E4-5).

Colonies grown 7 d on CMD at ca. 25 C in ambient light and for 14 d on oatmeal agar (Difco) and malt extract agar (Difco) at 20 C in alternating darkness and cool white fluorescent light > 9 cm diam. Aerial mycelium, diffusing pigment and odor lacking. Conidia forming in discrete 1--2 mm diam. pustules with little or no conidial production from mononematous conidiophores apart from the pustules. Conidia on all media slowly becoming green (26E5-6) on oatmeal agar and CMD but remaining cream colored or more yellow after two weeks on malt extract agar. Pustules compact and very easily dislodged from the agar surface, formed of vesicular or pseudoparenchymatous, thin-walled, 4.0--4.5 mm wide cells arranged in chains that tend to branch dichotomously near the surface of the pustule. Phialides clustered on terminal cells of the chains of cells, subglobose to ampulliform and sharply constricted toward the tip, 5.5-7.0 mm long, 3.5--4.0 mm in the middle, 3.0--3.5 mm at the base. Awl-like, terminally fertile, ca. 50 mm long extensions of conidiophores conspicuously arising from each pustule, each ca. 5 mm wide at the base and bearing a single, terminal, ca. 15 mm long, subulate phialide tapering from ca. 3 mm wide at the base. Often short branches bearing ampulliform phialides arising from near the base of the long conidiophores. Conidia oblong to ellipsoidal, 4.0--4.5 x 2.5--3.0 mm, smooth, lacking a visible basal abscission scar. Chlamydospores abundantly formed, globose to subglobose, ca. 8 mm diam., terminal and intercalary in hyphae, solitary or aggregated into clusters.

Known distribution. Colombia, Brazil (Rondónia, Pará)

Cladogram of Trichoderma stromaticum and related species:

cladogram


Last Modified: 2/29/2012