Biological Control Of Powdery Mildew On Cucurbits Using Telletiopsis pallescens In Egypt

• Shawky M. El-Desouky, Plant Pathology Research Institute, Agricultural Research Center, Giza, Egypt.
  E-mail: shawkidesouki@yahoo.com

Abstract

Telletiopsis pallescens Gokhale is a naturally occurring basidiomycetes fungus isolated from powdery mildewed squash leaves grown in open fields at Giza during the dry summer of 2001. The efficacy of T. pallescens was evaluated as a biocontrol agent against powdery mildew (Sphaerotheca fuliginea) on squash and cucumber. Control trials were conducted under a greenhouse conditions and open fields by spraying T. pallescens spore suspension or spraying with culture filtrate. Mildew severity and conidial density were assessed weekly starting one week from the first spray till the end of the growing period. Spore suspension or culture filtrate of T. pallescens provided complete control of powdery mildew on both squash and cucumber plants. Both hosts treated with a spore suspension or culture filtrate had a significant reduction (P< 0.05) in the severity of powdery mildew infection compared with plants treated with distilled water or those untreated. Also, the density of S. fuliginea conidia was significantly reduced. There were no significant differences between plants treated with spore suspension and the others treated with culture filtrates. The hyphae and conidiophores of S. fuliginea were shrunked, collapsed and disintegrated within 24 h after treatment. Mildew structures were absent on the surface of leaves 72 h after treatments. Biocontrol activity of T. pallescens appears to be as eradicant was and associated with enzymes or metabolites produced in the culture filtrate. Results demonstrated the potential of T. pallescens for biological control of cucurbit powdery mildew under commercial growing conditions.