Biological Control of Rambutan Post-Harvest Anthracnose (Colleotrichum gloeosporioides) by Combined Treatment of Trichoderma harzianum-TrH40 Culture Filtrates and Calcium Salts

Abstract

Trichoderma harzianum-TrH40 isolated from soil samples from rambutan (Nephelium lappaceum) orchards had antagonistic effects with combination of CaCl₂ salts on growth, activity, and infection of rambutan fruits by anthracnose (Colleotrichum gloeosporioides). Lower growth rate of spore germination, radial mycelial growth, and infectivity of anthracnose pathogen was observed at higher molar concentration of CaCl₂ by in vitro studies. Germination rate was 0.5% when 1M CaCl₂ was combined with T. harzianum-TrH40 spore suspension. The disease incidence and severity of anthracnose were least on wounded fruits that had been dipped in a solution containing of 1,100 mg of CaCl₂ per liter and T. harzianum-TrH40, which contained 10⁶ spores/ml. Furthermore, disease incidence and severity with combined treatments were correlated significantly and effectively reduced infection in vivo in rambutan fruits.

Key Words:

• Trichoderma harzianum
• anthracnose
• Colleotrichum gloeosporioides
• CaCl₂
• rambutan
• Nephelium lappaceum
• post harvest

ACKNOWLEDGMENTS

The financial support of the Sri Lanka Council of Agricultural and Research Policy (CARP) is greatly acknowledged.