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The rise of fungal canker and vascular diseases in cultivated and native woody plants: a California case study.

Florent Trouillas: Department of Plant Pathology, UC Davis

<div>California leads the world in the production of many fruit and nut crops. Fungal canker and vascular diseases that affect these crops have long been known in California, however, their proliferation in recent years has been of increasing concern. Most California vineyards and orchards are likely to become affected by at least one or more canker or vascular diseases, impacting their yield, longevity and profitability. Canker and vascular diseases are caused by taxonomically unrelated fungal pathogens belonging mainly to the families Botryosphaeriaceae, Diatrypaceae, Diaporthaceae, Togniniaceae and Valsaceae. These pathogens generally infect vines and trees through wounds including pruning wounds, cracks and other injuries and may act alone or jointly to cause disease, sometimes referred as a disease complex. Landscape and native trees in California can also be impacted by similar canker diseases. Alternatively, canker causing fungi may occur as saprophytes or endophytes (latent pathogens) on the native vegetation, which may serve as natural inoculum reservoir for canker diseases affecting fruit and nut crops. In recent years, California has been severely affected by climate change, resulting in long periods of drought. Increased plant stress due to water limitation and heat, increased acreage of fruit and nut crops and the general intensification of agricultural practices are factors that may have contributed to the expansion of fungal canker diseases.</div>