African Journal of Biotechnology Vol. 5 (8), pp. 648-652, 18 April 2006   

ISSN 1684–5315 © 2006 Academic Journals        

Full Length Research Paper

Bioassay of Geniculosporium species for Phytophthora megakarya biological control on cacao pod husk pieces

P. R. TONDJE¹*, K. P. HEBBAR², G. SAMUELS⁴, J. H. BOWERS³, S. WEISE⁵, E. NYEMB¹, D. BEGOUDE¹, J. FOKO⁺ and D. FONTEM⁶

¹ Regional Biological control and Applied Microbiology Laboratory, Institute of Agricultural Research for Development ( IRAD ), P.O. Box 2123 Yaoundé, Cameroon.

²MARS Inc./US Deparment of Agriculture, Agricultural Research Service, Plant Science Institute, Alternate Crops Systems Lab, Beltsville, MD 20705, USA.

³ US. Deparment of Agriculture (USDA), Agricultural Research Service (ARS), Plant Science Institute (PSI), Alternate Crops Systems Lab. Beltsville, MD, 20705 USA.

⁴ US. Deparment of Agriculture (USDA), Agricultural Research Service (ARS), Plant Science Institute (PSI), Systematic and Mycology Lab. Beltsville, MD, 20705 USA.

⁵International Institute of Tropical Agriculture (IITA), HFS- P.O.Box 2008 Yaounde, Cameroon.

⁶University of Dschang,  Faculty of Agronomy and Agricultural Science, P.O.Box 222, Dschang - Cameroon.

^*Corresponding author: Email: prtondje@yahoo.com.

Accepted 17 March, 2006

Fungal endophytes (Geniculosporium sp.) isolated from cacao leaves were screened for biological control of Phytophthora megakarya the cacao black pod disease pathogen, using Cacao Pod Husk Pieces (CPHP).  CPHP were pre-treated with spore suspensions of Geniculosporium sp. [BC13 (GJS 01-196), BC108 (GJS 01-192), BC118 (GJS 01-197), BC177 (GJS 01-198)], and were infected with P. megakarya zoospore suspensions (10⁵ zoospores/ml). Effects on P. megakarya were noticed at pod infection, mycelia growth inside infected tissues, and fungal sporulation, that are major stages of the black pod disease cycle on cacao pods. CPHP pre-treated with BC108 expressed the lowest early Infection Index (EII), but could not control disease progress into infected cacao pod husk tissues. On CPHP pre-treated with BC13, average growth rate of the necrosis was significantly reduced, but no control on P. megakarya sporulation was observed, while CPHP pre-treated with BC177 significantly reduced P. megakarya sporulation.

Key words: Cacao, biological control, Geniculosporium sp, endophytes, Phytophthora megakarya, pod husks pieces.