Indagini sugli endofiti patogeni in materiale vivaistico di piante forestali ornamentali e sulle misure per ridurne l’azione sulle crisi da trapianto
Author(s)
Rocco, Eleonora
Date Issued
February 27, 2009
Type
Doctoral Thesis
Abstract
This PhD Thesis has brought meaningful contributions to the knowledge on the endophytic fungal pathogens in nursery ornamental forest plants and on the related repercussions on the death of the plants in the new plantations (transplant crisis). With reference to the deciduous Populus genus, considering clonal materials, and to the evergreen Quercus ilex, as seed populations, researches were carried out on the presence of endophytic pathogens in the propagation material (cuttings and acorns), on their “infections” in the nursery plants with time, also in connection with the site, the genetic material, the water regimes and the fertilization, on the influence of the hydration or dehydration of the plants during the transplantation toward their chance to be isolate after the transplanting, the possible induction of bark necrosis and the transplant crisis.
The research has first of all evidenced that the acorns (holm oak) are free from endophytic pathogens, while the cuttings (poplar) can contain great amount of them, however without any means of access to the new seedlings.
It was furthermore observed that, in the poplar seedlings, the infections of endophytes agents of bark necrosis, as Phomopsis, Cytospora, Discosporium, Fusarium, primarily triggered by the rains, is mainly reliant on the local inoculum, it fluctuates with the host genus and it increases with the water stress of the plants.
The studies have finally shown as whereas a loss of the water content of the plants during the transplantation, as it happens by the air exposure, strongly increases the possibility to isolate endophytic bark pathogens, the appearance of their symptomatic attacks and the incidence of transplant crisis, on the other side a rehydration of the same plants by water immersion drastically reduces the aforesaid phenomena.
The investigations on Quercus ilex, in which bark endophytic pathogens of the genera Biscogniauxia, Discula, Phomopsis, etc. have been found, basically confirmed the results obtained on poplar, with the exception of a decrease in the bark endophytic pathogens by the intervention of balanced manurings and a very limited production of fruiting bodies by above mentioned mycetes during the transplant crisis.
To the light of these researches, by a practical point of view, the risks of transplant crisis therefore could be in most cases reduced by: setting up, whenever possible, the nurseries in areas with a low inoculum pressure; practicing balanced fertilization and avoiding any water stress in the nurseries; completely avoiding any dehydration of the plants during transplanting and, however, promoting their good hydration before transplantation.
Additional information
Dottorato di ricerca in Protezione delle piante
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