| Grape Powdery Mildew (Uncinula
necator)
Disease pressure was normal to high in 2005.
Performance of DMIs and “amines” was
as expected. Spiroxamine monitoring data have
been reported for 2004. The sensitivity of the
populations stayed in the range observed in the
previous years.
Recommendations:
DMI´s should only be used as preventative
and not in a curative manner. “Amines” should
preferably be used as preventative and not in
a curative manner.
The existing strategy for effective disease
control and resistance management continues to
be successful and the use recommendation is a
maximum of 4 applications per season, before
symptoms occur. The strategy includes the use
of mixtures or alternation with non-cross resistant
fungicides.
To ensure that SBI's can remain as the effective
basis for Uncinula control in vines, the use
of the full-recommended rate (either alone or
in mixture), recommended timing, application
volume and accurate treatment of each row should
be adhered to.
Apple Scab (Venturia inaequalis)
The performance of DMI’s
was good on this disease
in 2005 when compounds were
used according to the manufacturers’ and
FRAC recommendations. Sensitivity
data (2005) indicated that
no new sensitivity classes
have appeared since 1993,
although the most sensitive
class have disappeared as
shown from 2003 compared
to 1993.
Recommendations:
DMI fungicides, which are
labelled for scab control,
are not recommended for season
long use and a maximum of
4 DMI sprays either alone
or in mixture is recommended.
Where repeated fungicide
applications are required,
DMI's should be used in mixtures
or (block) alternations with
a non-cross resistant fungicide.
Application of recommended
label rates is important.
Preventative applications
should always be the first
choice with DMI’s.
Curative applications are
only recommended when accurate
disease warning systems are
available.
Apple Powdery Mildew (Podosphaera
leucotricha)
No complaints were received
on the performance of DMI’s
when compounds were used
according to the manufacturers’ recommendation
and FRAC recommendations.
For recommendations see General
Recommendations.
Soybean rust (Phakopsora
pachyrhizi)
See the FRAC-Brazil website
for information (frac@frac-brasil.org.br)
when available.
Monitoring methods for baseline
establishment and follow-up
are being developed.
Banana Sigatoka (Mycosphaerella
fijiensis)
The conclusions and guidelines
of the Feb. 2004 meeting
of the FRAC Banana Working
Group are available on the
FRAC Website.
Apple Powdery Mildew (Podosphaera
leucotricha)
No complaints were received
on the performance of DMI’s
when compounds were used
according to the manufacturers’ recommendation
and FRAC recommendations.
For recommendations see General
Recommendations.
Soybean rust (Phakopsora
pachyrhizi)
See the FRAC-Brazil website
for information (frac@frac-brasil.org.br)
when available.
Monitoring methods for baseline
establishment and follow-up
are being developed.
Banana Sigatoka (Mycosphaerella
fijiensis)
The conclusions and guidelines
of the Feb. 2004 meeting
of the FRAC Banana Working
Group are available on the
FRAC Website.
Fenhexamid (Hydroxyanilides)
Considered a SBI with activity
on Botrytis cinerea, which
is a high-risk disease. New
biochemical mode of action
and no cross-resistance with
other botryticides. Targets:
4,4-dimethylfecosterol and
4,alpha-dimethylfecosterol
in Sterol Biosynthesis pathway
(C4 demethylation). Regarded
as an inhibitor of C3-ketoreductase.
2005 monitoring studies are
in progress
Recommendations for use
of Fenhexamid: use fenhexamid
only protectively.
Straight product:
Spray schedules with a maximum
of 3 treatments per season:
max. 1 application with fenhexamid
Spray schedules with 4-5
treatments/season: max. 2
applications with fenhexamid
Spray schedules with 6 and
more treatments: at the maximum
one third of all Botryticide-applications
Mixtures:
Both partners - if applied
alone at the dose used in
the mixture - must have sufficient
activity against Botrytis.
Not more than 50% of all
Botryticide-treatments should
be made with fenhexamid-containing
mixtures.
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