Effectiveness of Trichoderma spp. secondary metabolites formulation in controlling vascular streak dieback of cacao

Abstract

Vascular-streak dieback (VSD) is the main disease of the cacao plant caused by Ceratobasidium theobromae. The VSD disease can potentially reduce cacao yields by up to 45%. VSD control using secondary metabolites of Trichoderma spp. can suppress the disease incidence in the field. The research aimed to study the effectiveness of secondary metabolites of Trichoderma spp. in controlling VSD diseases in field conditions. This research performed in cacao fields owned by a farmer in Rahmat Village, Palolo Subdistrict, Sigi Regency, Central Sulawesi, Indonesia, that were infested by VSD. Treatments were applied using a randomized block design and replicated 5 times with 10 plants of each. The formulations used in the treatment were; liquid of T. virens, liquid of T. amazonicum, powder of T. virens, powder of T. amazonicum, granulates T. virens, granulates T. amazonicum, chemical fungicide (as a comparison), and control. The liquid formula formulated with molasses as carrier material, the granulate formula used zeolite, compost, and peat, whereas the powder formula used lactose. The liquid formula was applied through root infusion, granulated formula was sprinkled around the rooting area, and the powder by spraying on all parts of the plants. The observation was about the infection symptom, disease incidence, and cacao production/yield. The result showed that T. virens and T. amazonicum secondary metabolites can suppress the disease incidence of VSD by 8.61–19.50% and improve cacao production by 12.19-37.01%. The most effective formulation suppressing the disease’s incidence is a liquid formula applied through root infusion.