Trichoderma from Aceh Sumatra reduce Phytophthora lesions on pods and cacao seedlings

Publication date: October 2015 Source:Biological Control, Volume 89 Author(s): Rina Sriwati , Rachel L. Melnick , Rizky Muarif , Mary D. Strem , Gary J. Samuels , Bryan A. Bailey The cocoa tree, Theobroma cacao L., suffers large yield losses in Aceh Indonesia due to the disease black pod rot, caused by Phytophthora spp. Despite having the largest area under cacao production in Sumatra, farmers in the Aceh region have low overall production because of losses to insect pests and black pod rot. Trichoderma spp. were isolated from the roots and leaves of cacao trees and screened as potential biological control agents. Isolates used in the study were Trichoderma asperellum isolates T2 and T4, Trichoderma longibrachiatum isolates T15 and T16, and Trichoderma virens isolates T1 and Tv. T1, T2, T4, and Tv completely colonized and destroyed Phytophthora tropicalis and Phytophthora palmivora mycelium in precolonized plate assays. All six isolates reduced P. tropicalis, but none reduced the growth of P. palmivora in dual plate assays. Phytophthora growth was suppressed on MIN media amended with sterile heat inactivated Trichoderma culture filtrates, with Tv best suppressing growth of both Phytophthora spp. T. virens isolate Tv was the only isolate observed coiling around P. tropicalis mycelium and disrupted the formation of P. palmivora sporangia. Of all six isolates, only Tv reduced P. palmivora lesion expansion in a detached pod assay, reducing severity by 71%. Tv also reduc...

Source: Biological Control - June 10, 2015 Category: Biology Source Type: research