Baseline information on agricultural practices in the EU ... - Europabio

years due to the formation of sclerotia, or because it can survive on organic material and the roots of
many host plants.
Other fungal diseases of high importance in Europe are Cercospora leaf spot (Cercospora beticola),
powdery mildew (Erysiphe betae), rust (Uromyces beta) and Ramularia leaf spot (Ramularia beticola).
Leaf spot disease may cause very heavy damages in the warmer regions of Southern Europe.
Sugar beet plants are susceptible to rhizomania ("root madness") which turns the bulbous tap root
into many small roots making the crop economically unprocessable. The disease is caused by the
Beet necrotic yellow vein virus (BNYVV), transmitted by the protozoan Polymyxa betae. The survival
structures of Polymyxa are highly resistant spores that can survive in soils for more than 15 years.
Upon germination of these structures Polymyxa zoospores with BNYVV that resides in the spores can
infect new plants.
It is not possible to control Polymyxa with fungicides or soil disinfestation. Using tolerant varieties is
the only technique to be able to continue growing beets. In France, the Netherlands and many other
countries 100% of the varieties are (partially) tolerant to BNYVV (CIBE-CEFS, 2010, ITB, IRS). Early
sowing and a good soil structure (water draining) delay infestation limiting damage (IRS). Recently
classic rhizomania tolerance seems to be broken in some fields in south of France. In these areas the
growers need to use varieties combining 2 sources of tolerance.
Strict controls are enforced in European countries to prevent the spread, but it is already endemic in
some areas (EPPO, A2 list). Up to 50-70% of root yield and two to more than four percentage points
of sugar content may be lost with severe attacks of rhizomania (EPPO). BNYVV is regulated within
the European Union in protected zones, currently Brittany (FR), Finland, Ireland, the Azores (PT), and
Northern Ireland (GB) 2 .
To determine whether and when it is necessary to carry out chemical plant protective measures (i.e.
spraying pesticides), farmers continuously monitor the crop for signs of stress and are regularly
informed about weather conditions likely to favour the development of specific pests and diseases by
e.g. technical research institutes or advisory services dedicated to sugar beet. In their decision crop
damage thresholds are taken into account.
Diseases affecting beet in store include scab (Streptomyces scabies), phoma (Phoma betae), wetrot
(Phytophthora megasperma), violet root rot (Helicobasidium purpureum) and rots caused by Fusarium
spp., Penicillium spp., Botrytis cinerea, Rhizopus nigricans and Sclerotinia sclerotiorum (BBRO).
2 Council Directive 2000/29 of 8 May 2000 on protective measures against the introduction into the
Community of organisms harmful to plants or plant products and against their spread within the
Community. OJ L 169, 10/07/2000, p.1-112. and
Commission Regulation EC/690/2008 of 4 July 2008 recognising protected zones exposed to
particular plant health risks in the Community. OJ L 193, 22/07/2008, p.1-6.
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