A non-destructive method for quantifying Cu, monitoring its residues, and downy mildew incidence on grapevine leaves after the application of copper-based antifungals

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Cu concentration (µg/cm² ) in Young leaves
Cu concentration (µg/cm² ) in Adult leaves
Introuduction & Main goals
Material & Methods
Results & Discussion
A non-destructive method
for quantifying Cu, monitoring its residues, and downy mildew incidence on grapevine leaves
after the application of copper-based antifungals
Fateme Sadeghian(1), Giovanni Mian(1), Piergiorgio Comuzzo(1), Lucilla Iacumin(1), Roberto Zanzotti(2),
Oscar Giovannini(2),Gianni Trioli(3), Nicola Pio Torraco(1), Emilio Celotti(1)
(1) Department of Agricultural, Food, Environmental and Animal Science, University of Udine, via delle scienze 206, Udine (UD), 33100.
(2) Fondazione Edmund Mach, via E. Mach 1, San Michele all’Adige (TN)(3) Vinidea srl, Ponte dell’Olio (PC)
Perennial crops such as grapevine are often sprayed with copper-based antifungals against one of the most critical diseases in viticulture, downy mildew (DM), caused
by the biotrophic oomycete Plasmopara viticola. Although the European Union has restricted the use of copper-based fungicides in organic farming since 2002, the
likely adverse eects on the environment, human health, wine quality, and soil contamination from diuse sources in some agricultural regions should be considered.
The aim of this work, funded under the INTAVIEBIO project (PSR - FVG) and in collaboration with AIAB FVG, was 1) to minimize the copper use by investigating
the variance of Cu coating on vine leaves and 2) to develop a non-destructive and rapid method to detect Cu on treated leaves using a new chemical probe that can
detect the presence of Cu through image analysis.
This study was carried out on ve organically managed vineyards in
north-eastern Italy. Copper-based fungicides were applied to the canopy
at dierent times during two growing seasons. The Cu dose applied to the
grapevine leaves ranged from 1.00 to 3.6 kg ha-1 .
The leaves were collected and washed
with a 1% nitric acid solution (HNO3).
For direct Cu analysis of the leaves, we also used
Cuprotesmo™ papers, which are particularly
sensitive to the presence of copper salts and
turn pink in the presence of the chemical
(the colour changes when the paper is moistened).
Monitoring Plasmopara viticola Conducted from June to August.
Percentage data collection for single adult leaf through visual
observation (diusion and severity) Data processing for each vineyard
reported with Meteorology data (rain ) and ICP -AES data.
After Cuprotesmo™ papers were well
dried under a laminar ow hood, images
of the coloured papers were taken with
a smartphone camera.
Table 1- The Average Infection Copper in ve studied vineyards during the second vegetative season.
The Average Infection Copper value is an important index that can hypothetically be achieved on a single-leaf vineyard over time.
Each agronomic situation is dierent from the others.
R2 of two vineyards was very low.
Totally 972 photos were tested by the mobile application(developed by image analysis based on photos have
taken from cupertesmo TM paper) and compered by ICP-AES data (Fig .5 - A ,B, C, and D)
Fig .1
Fig .2 Linear correlation
Fig .4
Fig .3
The data demonstrate that this approach (once well developed) can be used as a non-destructive, rapid and minimal knowledge required method for Cu measurement by farm managers.
Mean values of accumulated Cu on leaves ranged from 1.67 to 7.91 (μg/cm2), with different Cu concentrations on young and old leaves. Consequently, the effectiveness of Cu protection
against DM and the correlation between concentration and disease incidence were evaluated. A method defined for copper on leaves by image analysis with corresponding data previously
obtained from ICP-AES (young and adult). Climatic changes have increased the difficulty in preventing fungal infections. This has led to an increasing need for effective and rapid tools to
evaluate an intervention. The average value of copper from preventive coverage (≥ 3.53 μg /cm2 ) determined in this work is theoretically a parameter that would ensure adequate protection
while meeting regulatory limits and minimising environmental impact.In this context, an app based on mathematical models is developed to define active residual copper thresholds on the
leaf required to protect the crop. In this context, our work is a preparation for the development of this app, the initial results of which are promising.
The Cu concentration data obtained from a mobile
device application developed in the INTAVIEBIO project
(by image analysis)and that measured with ICP-AES were
compared on the same leaves.
A mobile device application developed in the INTAVIEBIO
project based on photos of Cuprotesmo™ paper moistened
by Mili-Q water on treated leaves by copper-based antifun-
gals during two vegetative seasons.
Cu concentration was analysed in the laboratory using ICP-AES
(Inductively Coupled Plasma - Atomic Emission Spectroscopy).
R
2
= trend of related infection intensity to the amount of average
residual copper on the adult leaf.
D
AB
C