Espécies de Lasiodiplodia associadas aos restos de poda de videira em três tipos climáticos do Nordeste brasileiro

Abstract

Botryosphaeria dieback, mainly caused by species of Lasiodiplodia, is considered one of the main grapevine trunk diseases in Northeastern Brazil and worldwide. The grapevine pruning debris left in the field are important source of inoculum for disease epidemics. Considering the importance of the disease and the pathogens involved in the colonization of pruning debris, the present work aimed to: a) identify the species of Lasiodiplodia associated with pruning debris in orchards located in three climatic types in Northeast Brazil; b) investigate the prevalence, distribution and diversity of the species; and c) evaluate the pathogenicity and aggressiveness of representative isolates of Lasiodiplodia species. Samples of grapevine pruning debris were collected in 22 orchards located in the regions of Vale do São Francisco (semi-arid climate), Vale do Siriji (tropical with dry summer climate) and Cariri in Ceará (savannah climate). Ninety-six Lasiodiplodia isolates were identified from grapevine pruning debris from DNA sequence data (tef1-α, ITS e tub2), with 11 species found: L. brasiliense, L. crassispora, L. euphorbiaceicola, L. hormozganensis, L. iraniensis, L. laeliocattleyae, L. mahajangana, L. newvalleyensis, L. pseudotheobromae, L. theobromae e L. viticola. Two isolates (Lasiodiplodia sp. and Lasiodiplodia sp. 2) did not cluster with any known taxa of this genus. It is the first report of L. mahajangana, L. newvalleyensis and L. viticola in grapevine in Brazil. Lasiodiplodia pseudotheobromae was the most prevalent, followed by L. brasiliensis. In the semi-arid climate, 10 species were recorded, predominantly L. hormozganensis and L. theobromae. In the savanna climate, seven species were observed, predominantly L. brasiliense and L. pseudotheobromae. In the tropical climate with dry summer, only three species were recorded, predominantly L. pseudotheobromae. A high diversity of species of Lasiodiplodia was observed in the pruning debris of the semi-arid and savannah climates, compared to that observed in the tropical climate with dry summer. The species of Lasiodiplodia were inoculated on detached branches of grapevine (cv. Vitória) and isolated from L. euphorbiaceicola and Lasiodiplodia sp. 2 were not pathogenic. The other species differed in terms of aggressiveness, with L. viticola being the most aggressive. The results show the great diversity of Lasiodiplodia species associated with grapevine pruning debris in Northeast Brazil and possible differences depending on the climate type.