A re-examination of Ceratocystis canker in California almond orchards

L.A. Holland, M.T. Nouri, D.P. Lawrence, R. Travadon, F.P. Trouillas
Ceratocystis canker of almond, caused by the fungal pathogen Ceratocystis fimbriata, has been found throughout California for over 50 years and is unique to California almond production systems. The disease appears to be ubiquitous in mechanically harvested almond orchards that repeatedly suffer bark injuries. However, factors that have promoted the widespread occurrence of this disease in almond orchards are still poorly understood and questions remain as to the origin, sources of inoculum and host range, as well as whether the pathogen can be transmitted directly from tree to tree by mechanical harvesters. Field diagnosis of Ceratocystis canker is challenging as symptoms of this disease are similar to other canker diseases of almond such as those caused by Botryosphaeriaceae spp. and Phytophthora spp. Research efforts in our laboratory have allowed the development of an effective protocol for the detection and isolation of C. fimbriata from diseased bark and cambium tissues, which has permitted the assembly of a broad collection of Ceratocystis strains throughout California almond-producing counties. The objectives of this study were to revisit the taxonomy and explore the genetic diversity of C. fimbriata from California almond to gain insights into its biology and epidemiology. Multi-locus phylogenetic analyses (β-tubulin, TEF1-α, 60S, MCM7 and cerato-platanin genes) indicates a new species and revealed no genetic variation within isolates obtained from almond in California.
Holland, L.A., Nouri, M.T., Lawrence, D.P., Travadon, R. and Trouillas, F.P. (2018). A re-examination of Ceratocystis canker in California almond orchards. Acta Hortic. 1219, 311-318
DOI: 10.17660/ActaHortic.2018.1219.47
almond, Ceratocystis, pathogen, disease, wood, damage

Acta Horticulturae