Source: FreshPlaza [summ. Mod.DHA, edited]https://www.freshplaza.com/article/9449161/avocado-dieback-is-an-increasingly-worrying-disease-for-subtropical-producers/
Dieback is becoming an increasingly important problem for avocado producers in Spain. Symptoms first become visible at the ends of branches, with progressive death of tissues towards the base of the trees. The disease has been present for a long time, but incidence and severity in the region are increasing steadily.
In 2022, the disease is especially concerning due to the dry weather and high temperatures. Levels of dieback resistance appear to vary between the locally grown avocado varieties. Research is being carried out at the University of Malaga to establish protocols for better control of the spread of the fungus.
[Dieback diseases of avocado and other fruit trees can be due to fungal species in several genera. The disease referred to above is the dieback caused by _Neofusicoccum parvum_ which has been spreading in southern Spain since the early 2000s (see link below). Symptoms progressively include death of twigs and branches; death of the whole tree may follow, especially for younger plants or if the host is already weakened by environmental or other stress factors. The pathogen has also been reported from other woody hosts and on avocado in other areas; it can also cause black spots on avocado fruits. Elsewhere, avocado dieback due to other species in the genus is also known.
The fungi can be spread by wind borne spores, contaminated materials, or mechanical means. Some species may be able to survive as endophytes in the plant, to emerge and cause disease when the host is exposed to external stress factors. Fungicides may be helpful in disease management if applied quickly enough.
Fungal dieback symptoms on avocado:https://ucanr.edu/blogs/Topics/blogfiles/30934_original.jpg
Additional news stories:https://www.freshplaza.es/article/9448928/la-muerte-regresiva-del-aguacate-es-una-enfermedad-cada-vez-mas-preocupante-para-los-productores-de-subtropicales/
(in Spanish) and viahttps://www.costanachrichten.com/spanien/politik-wirtschaft/avocados-aus-spanien-malaga-wassermangel-monokultur-axarquia-anbau-nachhaltigkeit-91707873.html
Information on avocado dieback due to _Neofusicoccum_ spp.:https://doi.org/10.1094/PDIS-91-8-1052B
, and viahttps://doi.org/10.1094/PDIS-02-11-0136
Fungal taxonomy viahttp://www.indexfungorum.org/names/names.asp