For healthy potatoes - Bayer CropScience

Azoles inhibit fungal
sterol synthesis
Azoles are organic chemical compounds
containing a five-membered ring structure,
including at least one nitrogen atom. If the
ring contains three nitrogen atoms and two
carbon atoms, one speaks of a triazole. In
the strictest sense, triadimefon, triadimenol,
tebuconazole and all of the other
azole fungicides Bayer has brought onto
the market belong to the class of triazoles.
Because of their mode of action, azole
fungicides are classified as DMIs, sterol
demethylation inhibitors. They block fungal
biosynthesis of sterols, components of
fungal cell membranes that are indispensable
for their stability and function. No
functional sterols – no intact cell membrane
– no fungal growth. Pharmaceutical
azoles act on the same principle.
The invention of tebuconazole meant a
further leap forward in azole development.
Like the older azole fungicides, tebuconazole
interferes with sterol biosynthesis, but
it is active against more fungal pathogens
in a greater number of crops than the earlier
azoles.
Back in August 1981, nobody in the
Bayer pharmacology labs anticipated that
the substance would eventually take the
market by storm. But Bayer had wisely
patented tebuconazole in European countries
and the USA soon after synthesis.
Years of development work followed, now
under the aegis of plant protection specialists
in Monheim. Finally, in 1988, the time
was ripe for market launch: the foliar fungicide
Folicur ® made its debut.
Tailored products
from the Folicur family
Folicur started as a fungicide intended
mainly for cereals. But, step by step, the
product became ever more diversified in
terms of formulation, application range
and mixtures. Today, it is registered and
sold in some 100 countries and applied to
more than 90 different crops. Various formulations
and mixtures are tailored to the
special needs of each crop and country.
Whether for tropical fruits such as mango
or banana, coffee or tea, vegetables in temperate
climates, potatoes, grapes, soybean
or oilseed rape – with its extraordinary
spectrum of activity, Folicur reliably protects
all of these crops against fungal diseases.
As indicated by the Folicur
slogan “It works. Year after year”,
DMI fungicides have been proving
their efficacy for 30 years
now. To preserve the current spectrum-of-control
and the performance
of azoles, guidelines
on Resistance Management
should be followed. One
tool for proactively
managing resistance
is the alternation or
combination of
DMIs with fungicides
from other classes
of active ingredients with different modes
of action. For example, the product
Nativo ® combines tebuconazole with the
strobilurine fungicide trifloxystrobin,
which acts as a respiration inhibitor in the
pathogen. Many other Bayer CropScience
products containing tebuconazole in
mixture with other fungicides that inhibit
different targets are sold around the world.
To name only a few, examples include
Folicur Multi, Falcon ® , Teldor ® combi and
Pronto ® Plus.
As this huge product range only
accounts for foliar fungicides. At the same
time, tebuconazole is being used very successfully
in seed treatment. In the early
1990s, Bayer introduced these products
under the brand of Raxil ® . Today, Raxil is
sold in some 50 countries around the globe
for the control of all of the major soil- and
seed-borne diseases of wheat and barley
seedlings. In Raxil Ultra, tebuconazole
comes at a double concentration; in other
seed treatment products, the fungicide is
mixed with the blockbuster insecticide imidacloprid.
Heavyweights on the
fungicide market
Whether used as a spray, as a seed
treatment or for special applications
such as turf protection or as a wood preservative,
tebuconazole is still a world-class
fungicide – even 25 years after first synthesis.
“Folicur and Raxil can be rightly
regarded as milestones in fungicide development”,
says Horst Stauff, Brand Communication
Manager Fungicides with
Bayer CropScience in Monheim. “And
although nearly twenty years on the market,
both products still represent the state
of the art”, Stauff adds.
With more than 300 million Euro sales
in 2005, Folicur is number two in the Bayer
CropScience portfolio, surpassed only by
the insecticide Confidor ® . “The massive
occurrence of Asian soybean rust in Brazil
gave Folicur another boost quite recently”,
explains Karin Wieczorek, Product Manager
Fungicides.
Taking the share of the world fungicide
market as a marker of success, Bayer Crop-
Science scores very well. Tebuconazole is
one of the world’s best-selling triazoles.
These days, triazoles constitute the most
important group of fungicides, accounting
for around 25 percent of the world market.
Bayer CropScience is highly engaged in
this market, and has constantly been
launching new azoles. After the success of
4 COURIER 2/06