Survival capacity of cacao top grafted with scions infected by vascular streak dieback pathogen: potential source of ceratobasidium theobromae long-distance spread

Authors: ADI, ASMAN - Hassanudin University; ROSMANA, ADE - Hassanudin University; AMIN, NUR - Hassanudin University; Bailey, Bryan; ALI, SHAHIN - University Of California, Davis

Submitted to: Archives of Phytopathology and Plant Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/7/2019
Publication Date: 11/13/2019
Citation: Adi, A., Rosmana, A., Amin, N., Bailey, B.A., Ali, S. 2019. Survival capacity of cacao top grafted with scions infected by vascular streak dieback pathogen: potential source of ceratobasidium theobromae long-distance spread. Archives of Phytopathology and Plant Protection. 52:13-14.

Interpretive Summary: Vascular streak dieback is a significant pathogen on cacao in Indonesia causing severe branch dieback and death of susceptible trees. The fungus Ceratobasidium theobromae causes the disease by invading the stems and killing the affected branches. Grafting of selected genotypes onto various rootstocks is used to rapidly propagate superior planting materials. Unfortunately, vascular streak dieback has potential for spread through grafting. This work proves that the pathogen causing vascular streak dieback can be transmitted through use of infected grafting materials. Infected grafts can survive long enough to be carried long distances to new planting areas spreading the disease. Care must be taking to avoid use of infected planting materials to limit spread of the pathogen. This knowledge gives producers of planting material, either commercially or on the farm, added incentive to insure their planting materials do not carry the pathogen. Cacao researchers and farm managers can use these results to guide their inspection and evaluation processes when introducing new grafted planting materials.

Technical Abstract: Vascular streak dieback (VSD) disease, caused by Ceratobasidium theobromae, is a significant cocoa diseases in Indonesia. Planting materials are often produced by top grafting raising the possibility that VSD may be spread through the use of infected grafting materials. When scions from VSD infected stems were used in grafting, both the rootstock and new growth from the scion developed symptoms of VSD. Infected scions often failed to establish when used for top grafting. This finding proves that the use of infected scions when top grafting can result in infected planting material with potential for spreading VSD.