Bombacopsis quinata: a new host for Oidiopsis haplophylli in Brazil

B.A. Halfeld-Vieira*, L.M.M. Ferreira and K.L. Nechet

Embrapa Roraima, BR 174, km 8, Distrito Industrial, CP 133, 69301-970, Boa Vista-RR, Brazil

*halfeld@cpafrr.embrapa.br

Accepted for publication 04/01/07

Bombacopsis quinata (Spiny Cedar, Cedro-Doce, Pochote, Saqui-Saqui, Cedro Espino) is a fast-growing native tree from central and northern South America, and grow naturally in a forest ecosystem in Roraima, Brazil.  This valuable species is used for wood exploration (Barbosa, 1990) and more recently has been cultivated in an agroforestry system.

Figure 1: Leaf spots in spiny cedar leaves infected by O. haplophylli.	Figure 2: Conidia and conidiophores of O. haplophylli. Bar = 100 µm.

In April 2006 at Mucajaí, Roraima, small necrotic spots were observed on spiny cedar plant leaves.  Symptoms ranged from mild chlorosis, to more severe necrotic spots (Fig. 1).  Early senescence of affected leaves was common.  Microscopic examination of the fungus on the abaxial leaf surface revealed conidiophores (180-250 µm x 7 µm, 3-4 septa, hyaline, occasionally branched) emerging through stomata (Figs 2 & 3).  Conidia were dimorphic, hyaline and smooth; primary conidia were lanceolate, 52-81 x 15-18 µm, mean length-to-width ratio 3.9; secondary conidia cylindrical 52-65 x 13-15 µm, mean length-to-width ratio 4.0 (Fig. 4).  The teleomorph was absent in our observations.  The anamorphic structures conform most closely to Oidiopsis haplophylli (Braun, 1987; Braun et al., 2002).

Figure 3: Conidiophores emerging from stomata. Bar = 50 µm.	Figure 4: Primary (A) and secondary (B) conidia of O. haplophylli. Bar = 50 µm.

Leveillula taurica, the true state of Oidiopsis haplophylli, has a wide host range covering many plant families.  However, until now the pathogen has only been recorded on a single Bombacaceae species, Adansonia digitata (Ebbels & Allen, 1979).  This is the first record of Oidiopsis haplophylli on Bombacopsis quinata.

References

Barbosa RI, 1990. Análise do setor madeireiro do Estado de Roraima. Acta Amazônica 20, 193-209.

Braun U, Cook RTA, Inman AJ, Shin H-D, 2002. The taxonomy of the powdery mildew fungi. In: Bélanger RR, Bushnell WR, Dik AJ, Carver TLW, eds. The Powdery Mildews: A Comprehensive Treatise. St. Paul, MN, USA: APS Press, 13-55.

Braun U, 1987. A monograph of the Erysiphales (powdery mildews). Nova Hedwigia 89, 1-700.

Ebbels DL, Allen DJ, 1979. A supplementary and annotated list of plant diseases, pathogens and associated fungi in Tanzania. Kew, UK: Commonwealth Mycological Institute.

The British Society for Plant Pathology