Usage of the relationship between the application rates of the active ingredient of fungicides and their residue levels in mature apples to creating a coherent system of MRLs
J Plant Dis Prot (2016) 123:101–108
DOI 10.1007/s41348-016-0015-2
ORIGINAL ARTICLE
Usage of the relationship between the application rates
of the active ingredient of fungicides and their residue levels
in mature apples to creating a coherent system of MRLs
Stanisław Sadło1 • Stanisław Walorczyk2 • Przemysław Grodzicki3 •
Bartosz Piechowicz1
Received: 12 October 2015 / Accepted: 18 April 2016 / Published online: 9 May 2016
Ó The Author(s) 2016. This article is published with open access at Springerlink.com
Abstract Setting of maximum residue levels (MRLs; tolerances in the USA) in crops requires a big amount of data
concerning residues from a number of supervised field trials
for each pesticide/crop combination. This task is time-consuming, costly and fairly complicated. Therefore, we initiated a study on the utilization of the interpolation method in
supporting and facilitating of assessing the value of the
MRLs which are now being in use, and in creating their
consistent system in the future. A mathematical formula for
predicting the initial pesticide residue level in mature apples
was developed by establishing the relationship between
application rates and residue levels of the pesticide active
ingredients in mature apples. This dependence was described
by a linear equation R0 = 1.2593 9 D, with coefficient of
determination r2 = 0.984, where D is an application rate of a
given substance. This relationship makes it possible to predict a residue level of other substances of fungicidal activity.
Thus, residue levels (both predicted by the formula and
obtained in the frame of Polish National Monitoring Program) of fungicides now used in apple orchards, in mature
apples were typically lower than those of the statutory
MRLs. Bearing in mind that the European Union policy is
directed towards substantial reduction in pesticide use, the
& Bartosz Piechowicz
1
Institute of Applied Biotechnology and Basic Sciences,
University of Rzeszów, Werynia 502, 36-100 Kolbuszowa,
Poland
2
Department of Pesticide Residue Research, Institute of Plant
Protection – National Research Institute, Władysława
We˛gorka 20, 60-318 Poznań, Poland
3
Department of Animal Physiology, Faculty of Biology and
Environment Protection, Nicolaus Copernicus University,
Lwowska 1, 87-100 Toruń, Poland
MRLs might be reconsidered in order to be set at lower
values.
Keywords Application rate Mature apples Maximum
residue levels Pesticide residues
Introduction
Among the food safety hazards for the consumers, pesticide residues, some bacterial pathogens (e.g. Salmonella
enterica) and foodborne viruses (e.g. norovirus) have been
identified as three most important risk factors [4]. In order
to safeguard consumers’ health and to promote principles
of good agricultural practice (GAP) in the use of pesticides,
maximum residue levels (MRLs; tolerances in the USA) of
pesticides have been set by all EU Member States applying
the same evaluation procedures and authorization criteria
in order to put a plant protection product (PPP) on the
market. These MRLs represent the highest concentrations
of pesticides (expressed in mg of active ingredient per kg)
which are legally permitted in food commodities, and they
are interpreted as the highest residue of a given substance
which may be found if a pesticide, registered and authorized, is applied according to label and, therefore, also to
principles of GAP [8]. So defined MRLs can be established
only when the residues in a crop resulting from particular
use pattern of the pesticide meet the public health risk
assessment criteria [8, 14, 19]. Despite international discrepancies between food safety regulations, compliance
with MRLs is still an essential prerequisite in trade of food
and agricultural products [6, 23, 24].
The residue levels of pesticides occurring in crops at
harvest time are dependent on many factors and are susceptible to influence of parameters such as a spray
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equipment used, a spray quality and conditions, crop
management, crop varieties, practices of growing, growth
stages at time of application and weather conditions [8].
But the most important determining factors are application
rate of the active ingredient (AI) per hectare and an interval
between the last application and the harvest (pre-harvest
interval PHI). It appears fairly obvious that relatively high
residues may be expected when pesticides are applied at
high doses later in growing season when plant growth rate
is slow [17].
For setting MRLs, residue data obtained from a number
of supervised field trials are required for each pesticide/
crop combination. This task is time-consuming, costly and
fairly complicated to perform [2, 3, 8, 16]. However,
development of a consistent approach for supporting and
facilitating estimation of the MRLs based on effective
application rate (dose) of the AI appears to be feasible. For
this reason, we initiated the field trials to investigate
whether the interpolation method may be efficient in predicting of the residue levels of fungicides now used in
apple orchards against diseases that potentially may
develop during fruit storage. Apples are particularly
interesting study object, since these fruits are heavily
exposed to pesticide contamination due to numerous pesticide treatments to whom they are subjected, and because
they are the most highly consumed fruits (along with
oranges) in the European Union countries and the USA.
Materials and methods
Field trials
The field trials were carried out in a commercial orchard
which was located near the Kraśnik town (Lublin Province,
south-eastern Poland) in 2011–2012. The orchard is specialized in providing apples for baby food production and
was certified in compliance with Integrated Pest Management (IPM) system by the Main Inspectorate of Plant
Health and Seed Inspection (PIORiN—Państwowa
Inspekcja Ochrony Roślin i Nasiennictwa).
Trial 1: To protect apples against fungal diseases that
develop during the cold storage, apple trees of Gloster
variety were sprayed with Switch 62.5 WG, a commercial
product containing 375 g kg-1 of cyprodinil and
250 g kg-1 of fludioxonil in the form of water dispersible
granules (WG), at a dose of 0.8 kg ha-1. Switch 62.5 WG,
which is a mixture of compounds belonging to anilinopyrimidine and phenylpyrrole chemical groups, exhibits a
protective and systemic activity against infections of fruits
and vegetables by Botrytis cinerea (grey mould).
Trial 2: One week before harvesting mature apples, and
submitting them to the storage room, apple trees of Lobo
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J Plant Dis Prot (2016) 123:101–108
variety were sprayed with Zato 50 WG, at a dose of
0.2 kg ha-1. Trifloxystrobin, the AI of this plant protection
product, belongs to the family of strobilurin fungicides and
exhibits systemic mode of action.
Trials 3 and 4: These two field trials were carried out on
the apple trees of Gloster and Lobo varieties, which were
sprayed with fungicides Merpan 80 WG and Captan 8 (...truncated)
