Doença de Petri da Videira - UTL Repository - Universidade Técnica ...

EXTENDED ABSTRACT
Several species of Phaeoacremonium and the species Phaeomoniella chlamydospora are
the causing agents of Petri disease in grapevines. These fungi also play an important role
in the esca complex pathology. In recent years, these diseases have been responsible for
sizeable damages and losses in the production of table grapes and wine production.
Therefore, it becomes imperative to advance the knowledge on these diseases, for better
understanding of their behavior and possible disease control.
In the present study, the pathogenicity of seven isolates of Pa. chlamydospora was
studied. For one of these isolates, studies were also carried out in the field to assess the
efficiency of new fungicidal products. Pathogenicity tests were carried out with all the
seven isolates in potted grapevine plants (in vivo assays) of the cultivar Touriga
Nacional, growing under greenhouse conditions during four months in order to register
canker development and to perform re-isolations. Two infection methods were tested,
using either mycelial fragments as inoculum (agar plugs) or spore suspensions (from
liquid cultures). Pathogenicity was confirmed for all the isolates of Pa. chlamydospora,
relative to control plants, which were not inoculated. It was possible to re-isolate Pa.
chlamydospora from all inoculated plants, while the percentage of re-isolation for not
inoculated plants was null. Isolate PL 2 produced the longest necroses. The highest
percentages of re-isolation were obtained with isolate T21 L330 when inoculation
occurred with spore suspensions or with isolate T16 L299 when inoculation occurred with
mycelial disks. The best percentage of re-isolation was observed when mycelial disks
were used as inoculum.
The efficacy of six new fungicide formulations was tested under field conditions for the
cultivars Syrah and Touriga Nacional. Results were compared to those obtained from
plants treated with carbendazim+flusilazol (Escudo ® ), which was used as a standard.
Products were applied once on the pruning wound. For each treatment, 18 replicates (1-
yr-old shoots) were used, which were inoculated with a spore suspension prepared from
250 mL malt extract medium inoculated with 3 mm diameter agar plugs cut from the
edge of colonies growing under darkness at 20ºC. Liquid cultures were incubated for 14
days on a reciprocal shaker at 90 rpm, filtrated and then diluted with SDW to a final
concentration of 10 5 spores mL -1 . Inoculation of test plants occurred one day after
fungicidal application. Approximately 50 µL of the spore suspension of Pa. chlamydospora
were applied on each pruning wound and the inoculated wounds were protected with
“Parafilm”.
Assessments were performed six months after inoculation by observation of the internal
symptoms, browning tissues or presence of necroses. The length of the shoots, the
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