Lasiodiplodia theobromae and Lasiodiplodia brasiliensis associated with dieback and canker in cupuaçu trees (Theobroma grandiflorum) in Brazil

Abstract

Cupuaçu (Theobroma grandiflorum) is a tropical fruit tree native to Northern Brazil. For decades, dieback symptoms have been observed in cupuaçu trees, leading to significant reductions in productivity. Between 2019 and 2020, during phytosanitary surveys conducted in orchards across the states of Acre and Amazonas, fungal isolates belonging to the Botryosphaeriaceae family were collected from the wood tissues of symptomatic plants. Based on morphological and multigenic analyses (TEF1-α, ITS, and TUB2), the isolates were classified as Lasiodiplodia theobromae and L. brasiliensis. Disease incidence was estimated at 15 % among plants showing canker and dieback symptoms, from which 20 isolates were obtained. Seven representative isolates from three distinct geographic regions were selected for species identification and pathogenicity testing. Multilocus phylogenetic analysis revealed that four isolates clustered with the reference strain of L. theobromae, while three clustered with L. brasiliensis. Pathogenicity tests demonstrated that both species were capable of inducing canker symptoms and dark lesions on wood tissues. This study is the first report of L. theobromae and L. brasiliensis causing dieback and canker on cupuaçu trees in Brazil.