13 research outputs found
Post-infection activity of fungicides against Phytophthora infestans on tomato (Solanum lycopersicum L.)
Abstract Late blight caused by Phytophthora infestans
is the most devastating disease of tomato (Solanum lycopersicum
L.) and causes important economically losses
if not properly controlled. Control is achieved mainly by
preventive fungicide applications. However, even if curative
applications are discouraged because they increase the
risk of resistance development in the target pathogens, in
practice fungicides may be applied also when the disease
is already present, a situation that commonly occurs in the
field. The aim of this work was to study the curative activity
of several fungicides toward P. infestans to determine
their efficacy when applied after the infection process. Nine
trials were performed in greenhouse using potted tomato
plants that were treated 24 h after inoculation. Disease
severity was assessed three times from the development
of the symptoms on the untreated plants and data analysed
using a linear mixed model. Differences in post-infection
control between the different chemical classes were found.
Metalaxyl-M and cymoxanil showed the best curative
activity while among the CAA fungicides, a good efficacy
was expressed by dimethomorph. Interestingly, evidence of
synergy between active ingredients having different modes
of action was observed such as in the mixtures containing
dimethomorph + ametoctradin, dimethomorph + pyraclostrobin
and fosetyl-Al + propamocarb. This study provided
useful information on the post-infection activity of some
fungicides used to control tomato late blight and should be
taken into account to perform more in depth studies at the field level and to improve the management strategies of the
disease