| 2.1. Review of sensitivity monitoring
2.1.1. Cereal diseases
Powdery mildew (Erysiphe graminis f.sp. tritici),
wheat
BASF, Bayer
In 2002 high frequencies of resistant isolates were
found in UK, Germany, Northern France, Belgium, Denmark
and Sweden. The G143A mutation was found consistently.
No resistance was found in Italy, Austria and very
low frequencies in Southern France.
Powdery mildew (Erysiphe graminis f.sp hordei), barley
BASF, Bayer, Syngenta
In general the frequency of resistant isolates increased
in 2002 compared to 2001, however the spread of resistant
barley powdery mildew isolates is slower than that
observed previously for wheat powdery mildew. No resistance
was detected in Denmark, Italy or the South of France.
Medium frequencies of resistance were detected in UK
and Scotland. The picture in Germany is rather heterogeneous
with higher values found in the northern regions. Higher
frequencies of resistance were found in Northeast and
eastern France and in Belgium. Field performance was
good when QoI products were applied in mixtures as
recommended by the QoI FRAC guidelines.
Septoria leaf spot (Septoria tritici), wheat
BASF, Bayer, Syngenta
Extensive monitoring programmes were carried out throughout
the wheat growing areas of Europe in 2002 using both
regional monitoring approaches and targeting analysis
of strains from high risk trial sites.
Field performance across Europe was good under high
disease pressure. However, in a few locations in South
West Ireland disease control was lower than expected.
This was associated with severe disease infections,
which were accentuated by agronomic factors coupled
with adverse weather conditions. In these sites, resistant
isolates were found.
In the monitoring programmes the vast majority of
tested isolates was sensitive across Europe. A low
frequency of resistant isolates was detected at specific
sites in the UK and to a lesser extent in Germany and
France.
The G143A mutation was identified for the individual
resistant isolates in 2002. In retrospective PCR analysis
of some isolates collected in 2001 a very low frequency
of the G143A was found indicating that the 2002 observations
are the result of an ongoing selection process. Also,
in 2001 the field performance has been good.
Due to the epidemiology of Septoria, the spread of
resistance is expected to be much slower than that
observed for wheat powdery mildew. Nevertheless, it
is critical in order to maintain the effectiveness
of QoIs to strictly implement, in practice, the guidelines
given below (see 2.2.1).
Brown rust (Puccinia recondita), wheat
BASF, Bayer, Syngenta
Performance of QoI fungicides against brown rust was
good. No resistant isolates were detected from widespread
monitoring studies in Europe in 2002, confirming the
fully sensitive picture already established.
Net blotch (Pyrenophora teres), barley
BASF, Syngenta, Bayer
Performance of QoI fungicides against net blotch was
good. Monitoring data from 2001 showed a fully sensitive
picture. 2002 monitoring data were not available at
the time of the meeting.
Leaf scald (Rhynchosporium secalis), barley
BASF, Syngenta
Performance of QoI fungicides against leaf scald was
good. Monitoring data from 2001 showed a fully sensitive
picture. 2002 monitoring data were not available at
the time of the meeting
2.1.2. Vine diseases
Downy mildew (Plasmopara viticola)
BASF, Bayer, DuPont, Syngenta
In 2002, disease pressure was high in the main grape
growing areas of Europe.
All companies carried out major monitoring programmes
in 2002 in France, Italy, Germany, Austria, Switzerland,
Spain, Greece and Portugal. Both semi-quantitative
bioassay and PCR techniques were used to generate data.
A frequency of 1-2% G143A identified through PCR diagnosis
was usually reflected as a resistant phenotype in bioassay
tests.
No resistant strains were detected in Austria, Portugal
and Greece. For the first time resistant strains could
be found in South West Germany and North West Spain.
In general, an increase in the frequency of detection
of the resistant strains was observed in France, Italy
and West Switzerland.
In less than 1% of isolates a second target site mutation
has been detected (F129L), however this mutation is
of minor importance due to both the low resistance
factors associated with this mutation and its low frequency
in the population.
Field performance of QoI fungicides, where the QoI
FRAC guidelines were followed, was good across Europe.
Powdery mildew (Uncinula necator)
Bayer, BASF, Syngenta
Disease pressure was rather low in 2002 and performance
of QoI fungicides was good.
No resistant isolates were detected in monitoring
programmes in France, Italy, Portugal, Germany and
Austria.
2.1.3 Pome fruit diseases
Apple scab (Venturia inaequalis)
BASF, Bayer
Disease pressure was high across Europe.
Monitoring was carried out in Germany, France, Italy,
UK, Netherlands, Belgium, Switzerland, the Czech Republic,
Poland, Spain and USA. Decreased sensitivity was found
throughout Germany, Italy and Poland using bioassays
and was linked to 2 different types of resistance mechanism:
metabolism and target site mutation (G143A).
Target site mutants (G143A) were found in trial sites
from Northern Italy and commercial orchards from Poland.
Compared to 2001, resistant isolates were not detected
at any additional sites in Northern Germany in 2002.
Performance of QoI fungicide programmes under both
trial and commercial conditions was generally good.
A clear lack of correlation between detection of target
site mutants and disease control was evident. Performance
complaints linked to target site resistance were only
recorded from Poland in 2002.
2.1.4. Cucurbit diseases
Powdery mildew (Sphaerotheca fuliginea)
BASF, Syngenta
High frequencies of resistant isolates have previously
been detected in Japan, Taiwan, Spain, Israel and Southern
France, and in these countries field performance was
affected. Resistance has also been previously detected
at several locations in the UK, Netherlands, North
West France, Italy and Korea.
Downy mildew (Pseudoperonospora cubensis)
BASF, Syngenta
Resistance has previously been detected in Japan and
Taiwan and field performance in these countries has
been reduced. No additional data was reported in 2002.
2.1.5. Potato/tomato diseases
Late blight (Phytophthora infestans)
Bayer, DuPont
No resistance was detected in all isolates collected
from potato crops in France, Germany, Netherlands,
UK, Belgium, Scandinavia, Portugal and Poland. Performance
remains good.
Early blight (Alternaria solani)
Syngenta
In 2001 reduced sensitivity isolates were detected
in USA. These isolates were collected from areas with
high incidence of early blight. The F129L mutation
was identified in these isolates and conferred a low
resistance factor. Studies are in progress in order
to investigate the significance of these isolates under
practical conditions.
2.2. Review of guidelines
2.2.1 Strategies and Guidelines for the 2003 season
Strategies for the management of QoI fungicide resistance,
in all crops, are based on the statements listed below.
These statements serve as a fundamental guide for the
development of local resistance management programs.
Resistance management strategies have been further
enhanced in order to be proactive and to prevent the
occurrence of resistance to QoI fungicides developing
in other areas and/or pathogens. Specific guidelines
by crop follow the general guidelines given here.
A fundamental principle that must be adhered to when
applying resistance management strategies for QoI fungicides
is that:
The QoI fungicides (azoxystrobin, famoxadone, fenamidone,
kresoxim-methyl, picoxystrobin, pyraclostrobin, trifloxystrobin,
fluoxastrobin, dimoxystrobin and oryzastrobin) are
in the same cross-resistance group.
1.
|
Fungicide programs must deliver effective disease
management. Apply QoI fungicide based products
at effective rates and intervals according to manufacturers
recommendations. Effective disease management is
a critical component to delay the build-up of resistant
pathogen populations. |
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2.
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The number of applications of QoI fungicide based
products within a total disease management program
must be limited whether applied straight or in
mixtures with other fungicides. This limitation
is inclusive to all QoI fungicides. Limitation
of QoI fungicides within a spray programme provides
time and space when the pathogen population is
not influenced by QoI fungicide selection pressure. |
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3.
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A consequence of limitation of QoI fungicide
based products is the need to alternate them with
effective fungicides from different cross-resistance
groups. |
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4.
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QoI fungicides, containing only the solo product,
should be used in single or block applications
in alternation with fungicides from a different
cross-resistance group. Specific recommendation
on size of blocks is given for specific crops. |
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5.
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QoI fungicides, applied as tank mix
or as a co-formulated mixture with an effective
mixture partner, should be used in single or block
applications in alternation with fungicides from
a different cross-resistance group. Specific recommendations
on size of blocks are given for specific crops. |
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6.
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Mixture partners for QoI fungicides should be
chosen carefully to contribute to effective control
of the targeted pathogen(s). The mixture partner
must have a different mode of action, and in addition
it may increase spectrum of activity or provide
needed curative activity. Use of mixtures containing
only QoI fungicides must not be considered as an
anti-resistance measure. |
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7.
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An effective partner for a QoI fungicide is
one that provides satisfactory disease control
when used alone on the target disease. |
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8.
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QoI fungicides are very effective at preventing
spore germination and should therefore be used
at the early stages of disease development (preventive
treatment). |
2.2.2 Specific Crop/Pathogen guidelines
2.2.2.1 Cereal diseases
Guidelines for using QoI fungicides on cereal crops
1.
|
Apply QoI fungicides according to manufacturers
recommendations for the target disease (or complex)
at the specific crop growth stage indicated. Effective
disease management is a critical parameter in delaying
the build-up of resistant pathogen populations. |
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2.
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Apply use rates recommended by the manufacturer
in order to ensure solid disease control and resistance
management. The FRAC QoI working group is concerned
with the trend towards the application of decreased
dose rates. |
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3.
|
Apply a maximum of 2 QoI fungicide containing
sprays per cereal crop. Limiting the number of
sprays is an important factor in delaying the build-up
of resistant pathogen populations. |
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4.
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Apply the QoI fungicide preventively or as early
as possible in the disease cycle. Do not rely only
on the curative potential of QoI fungicides. |
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5.
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Apply QoI fungicides in mixtures
to control cereal pathogens. At the rate chosen
each mixing partner on its own has to provide effective
disease control. Refer to manufacturers recommendations
for rates. |
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6.
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Split / reduced rate programmes, using repeated
applications, which provide continuous selection
pressure, must not be used. |
The companies, represented at QoI working group of
FRAC, emphasized again the importance of full adherence
to the above guidelines as well as to the label text
recommendations, full implementation of which must
be considered as necessary for effective disease control.
2.2.2.2 Vine diseases
Guidelines for using QoI fungicides on vines
Powdery mildew (Uncinula necator)
1.
|
Apply QoI fungicides according to manufacturers
recommendations for the target disease at the specific
crop growth stage indicated. Effective disease
management is a critical parameter in delaying
the build-up of resistant pathogen populations. |
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2.
|
Apply a maximum of 3 QoI fungicide containing
sprays per vine crop, solo or in mixture with effective
mixture partners from different cross-resistance
groups. |
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3.
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For table grapes, a maximum of 4 QoI fungicide
containing sprays per crop may be used when 12
or more fungicide applications are made. |
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4.
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Apply QoI fungicides preventively. |
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5.
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Apply QoI fungicides in single or
block application in alternation with fungicides
from a different cross-resistance group. |
Downy mildew (Plasmopara viticola)
1.
|
Apply QoI fungicides according to manufacturers
recommendations for the target disease at the specific
crop growth stage indicated. Effective disease
management is a critical parameter in delaying
the build-up of resistant pathogen populations. |
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2.
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Apply QoI fungicides preventively. |
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3.
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Apply a maximum of 3 QoI fungicide containing
sprays per vine crop, only in mixture with effective
partners from different cross-resistance groups. |
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4.
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Apply QoI fungicides in single or block application
in alternation with fungicides from a different
cross-resistance group. |
2.2.2.3 Pome fruit diseases
Guidelines for using QoI fungicides on pomefruit
Apple scab (Venturia inaequalis)
1.
|
Apply QoI fungicides according to manufacturers
recommendations for the target disease (or complex)
at the specific crop growth stage indicated and
adapted to size of trees. Effective disease management
is a critical parameter in delaying the build-up
of resistant pathogen populations. |
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2.
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Apply QoI fungicides preventatively. Under high
disease pressure the spray interval should not
exceed 7-10 days. |
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3.
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Apply a maximum of 3 QoI fungicide containing
sprays per crop. A maximum of 4 QoI fungicide applications
may be used where 12 or more applications are
made per crop. |
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4.
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QoI fungicides should preferably be applied in
mixture with partners contributing to the effective
control of the target pathogens. |
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5.
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A maximum of 2 consecutive QoI fungicide
sprays is preferred. |
Guidelines for using QoI fungicides on pomefruit where
target site mutants (G143A) of apple scab (Venturia
inaequalis) have been detected and simultaneously performance
was adversely affected (see section 2.1.3 for details)
1.
|
Apply QoI fungicides according to manufacturers
recommendations for the target disease (or complex)
at the specific crop growth stage indicated. Effective
disease management is a critical parameter in delaying
the build-up of resistant pathogen populations. |
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2.
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Apply QoI fungicides preventively at spray intervals
not exceeding 7-10 days. |
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3.
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Apply a maximum of 2 QoI fungicide containing
sprays per crop. A maximum of 3 QoI fungicide applications
may be used where 12 or more applications are
made per crop. |
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4.
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Do not apply consecutive QoI fungicide sprays. |
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5.
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Always apply QoI fungicides in mixture
with partners contributing to effective control
of the target pathogens. |
2.2.2.4 Potato and tomato diseases
Guidelines for using QoI fungicides on potatoes and
tomatoes
Late blight (Phytophthora infestans)
1.
|
Apply QoI fungicides according to
manufacturers recommendations for the target disease
(or complex)
at the specific crop growth stage indicated. Effective
disease management is a critical parameter in delaying
the build-up of resistant pathogen populations. |
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2.
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Where QoI fungicide products are applied alone
do not exceed 1 spray out of 3 with a maximum of
3 sprays per crop. Do not use more than 2 consecutive
applications. |
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3.
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Where QoI fungicide products are applied in
mixtures (co-formulations or tank mixes) do not
exceed 50% of the total number of sprays or a maximum
6
QoI fungicide applications whichever is the lower. Do not use more than 3 consecutive
QoI fungicide containing sprays. |
Early blight (Alternaria solani)
Where QoI fungicide products are applied solo do
not exceed 33% of the total number of sprays or a maximum
of 4. Where mixtures (co-formulations or tank mixes)
are used do not exceed 50% of the total number of sprays
or a maximum of 6 QoI fungicide applications, whichever
is the lower.
2.2.2.5 Cucurbit diseases
Guidelines for using QoI fungicides on cucurbit vegetables
Apply QoI fungicides according to manufacturers recommendations
for the target disease
(or complex) at the specific crop growth stage indicated. Effective disease
management is
a critical parameter in delaying the build-up of resistant pathogen populations.
1.
|
Apply a maximum of 3 QoI fungicide sprays per
crop. |
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2.
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Use a maximum of 1 QoI fungicide spray out of
every three fungicide applications. |
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3.
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Do not use consecutive applications of QoI fungicides. |
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4.
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Apply QoI fungicides in alternation with fungicides
from a different cross-resistance group with satisfactory
efficacy against the targeted pathogen(s). |
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5.
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Continue QoI fungicide alternation
between successive crops. |
2.2.2.6 Guidelines for using QoI fungicides on greenhouse
grown non-cucurbit vegetables
1.
|
Apply QoI fungicides according to manufacturers
recommendations for the target disease (or complex)
at the specific crop growth stage indicated. Effective
disease management is a critical parameter in delaying
the build-up of resistant pathogen populations. |
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2.
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Use a maximum of 1 QoI fungicide spray out of
every 3 fungicide applications. |
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3.
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Do not use consecutive applications of QoI fungicides. |
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4.
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Apply QoI fungicides in alternation with fungicides
from a different cross-resistance group with satisfactory
efficacy against the targeted pathogen(s). |
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5.
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Continue QoI fungicide alternation
between successive crops. |
2.2.2.7 Guidelines for using QoI fungicides on other
multiple spray crops (non-cucurbit field vegetables
and ornamentals)
1.
|
Apply QoI fungicides according to
manufacturers recommendations for the target disease
(or complex)
at the specific crop growth stage indicated. Effective
disease management is a critical parameter in delaying
the build up of resistant pathogen populations. |
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2.
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Observe spray limitations in the spray guideline
table shown below. |
Spray guideline table:
Total
number of spray applications per crop |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
11 |
12 |
>12 |
Maximum
recommended
Solo QoI fungicide sprays |
2
|
2 |
2 |
2 |
3 |
3 |
3 |
3 |
4 |
* |
Max.
recommended QoI fungicide sprays in mixture |
2 |
2 |
3 |
3 |
4 |
4 |
5 |
5 |
6 |
* |
* Where more than 12 fungicide applications are
made, do not use more than one third of all fungicide
applications with QoI fungicides solo or 50% where
used in mixture.
When using a QoI fungicide as a solo product,
the number of applications should be no more than
1/3 (33%) of the total number of fungicide applications
per season.
For QoI mixes in programs in which tank mixes
or premixes of QoI with mixing partners of a different
mode of action are utilized, the number of QoI
containing applications should be no more than ½ (50%)
of the total number of fungicide application per
season.
In programs in which applications of QoI are made
with both solo products and mixtures, the number
of QoI containing applications should be no more
than ½ (50%) of the total number of fungicide
applied per season.
2.2.2.8 Banana
Guidelines for using QoI fungicides on banana
Black Sigatoka (Mycosphaerella fijiensis)
The following guidelines were updated following
a FRAC meeting held in San Jose, Costa Rica on
August 8th, 2000. This meeting was called specifically
to discuss what changes to the guidelines should
be recommended by FRAC in response to the detection
of strains of Mycosphaerella fijiensis resistant
to the QoI fungicides in multiple locations in
Costa Rica. Revised guidelines for QoI fungicides
are listed under items 16 to 23.
1.
|
Field experience
in bananas in Central America has shown that
M. fijiensis can develop resistance to the
DMI fungicides. The DMIs are and will continue
to be very key tools for the efficient control
of Black Sigatoka in bananas. An effective
anti-resistance strategy must be followed
when using these materials, in order to protect
their fungicidal performance over the long
term.
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2.
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In general terms, the use of fungicides with
a different mode of action applied in tank
mixtures or in alternated sprays are both suitable
approaches to diminish the risk of resistance
development. These use strategies are particularly
valuable in the case of site specific systemic
fungicides and in situations when there is
a need to cope with a shift towards decreased
sensitivity. The anti-resistance strategies
only allow a limited number of sprays with
the systemic fungicides (see items 9-10). Therefore,
the use of these materials in alternation with
fungicides belonging to other classes seems
to be the best approach in order to allow the
necessary total number of sprays which are
required with the systemic fungicides, for
efficient Black Sigatoka control over the whole
high pressure period. |
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3.
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The use of the full recommended label rate
of DMIs is strongly urged (straight DMI use). |
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4.
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The DMIs must be used at least ¾ (75%)
of their full recommended label rates when
they are applied in tank mix with other systemic
fungicides. When tridemorph is the partner
compound, it must be added at least at 2/3
(67%) its commercially recommended label rate.
In the case of tank mixtures with benzimidazoles,
these fungicides must be used at their full
recommended label rates. Finally, when mancozeb
is used as the partner material for site specific
systemic fungicides, these DMIs must be applied
at their full recommended label rates. |
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5.
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Single alternation of DMIs with other systemic
fungicides is recommended. Repeated (sequential)
applications of DMIs (either alone or in tank
mixtures with other systemics) must be limited
to no more than 2 consecutive sprays (i.e.
block of 2 sprays). The same recommendation
is also applicable to tridemorph. |
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6.
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All the fungicides belonging to the DMI’s
class are considered to be a single product
group, amongst which there is in general some
degree of cross-resistance. Therefore, alternation
or mixtures of DMIs must not be recommended
for the purpose of resistance management. |
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7.
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The benzimidazole fungicides must not be
applied in consecutive sprays. The applications
of benzimidazole fungicides should not exceed
a total of 6 sprays in a period of 12 months.
It is also recommended that this class of fungicides
must be always used in mixtures with mancozeb. |
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8.
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In the case of straight applications of
the DMIs, the number of sprays against Black
Sigatoka must not exceed a total of 8 cycles
during any 12 month period (a maximum of 6
total sprays in the case of Yellow Sigatoka). |
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9.
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The maximum number of DMI's sprays for controlling
Black Sigatoka might be increased to a total
of 10 applications in a 12 month period, if
the DMIs are always applied in mixtures with
other systemics (7 maximum sprays in the case
of Yellow Sigatoka). |
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10.
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The number of tridemorph sprays with this
fungicide used either alone, in mixture with
the DMIs or other classes of fungicides must
not exceed a total of 12 applications within
a 12 month period. |
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11.
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Protective (preventative) fungicides are
considered to be a very valuable and necessary
tool for the banana Sigatoka control programs. |
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12.
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The systemic fungicides must only be applied
in oil or oil-water emulsions. |
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13.
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A DMI-free period of at least 2 (and if possible
3-4) consecutive months, during the periods
of lower disease pressure is recommended. |
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14.
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DMIs should be applied to achieve as early
a curative control as possible. |
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15.
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Eradicative use of DMIs should be avoided. |
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16.
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A maximum of 4 cycles of QoI fungicides should
be used during a 12 month period. |
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17.
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QoI applications should be limited to a maximum
of 3 exposure periods per calendar year. |
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18.
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QoI fungicides should only be applied
in April, August and December in Costa Rica.
In other countries, exposure periods should
be defined locally, with 3 months between
exposure periods as a working guideline.
In regions where high levels of QoI resistance
have been detected, QoI sprays should be discontinued
until there is evidence of a significant increase
in the frequency of sensitive strains.
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19.
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Do not exceed recommended label spray intervals. |
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20.
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Do not apply QoI fungicides in successive
sprays |
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21.
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Apply full recommended label rates of the
QoI fungicides alone or in mixtures. Mixtures
with fungicides with different modes of action
are valuable for disease control and resistance
management. |
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22.
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QoI fungicides should be applied to give
as early a curative control as possible. |
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23.
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The eradicative use of QoI fungicides should
be avoided. |
2.3.
Communication plans
The above WebPages will serve as the main communication
vehicle for the group.
Details of sensitivity monitoring methodology
for various diseases will be edited to a common
template and be available on the web by the end
of Q2 2003.
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