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Virus yellows (BYV and BMYV)

Symptoms: On older leaves yellowing of the interveinal tissue. As the disease progresses, yellowing becomes more intense, the leaf blade becomes thickened and brittle. In the field, the disease first occurs in colonies and later on spreads over the whole field.
Symptoms: Beet mild yellowing virus (BMYV): yellowish-orange colouring, often secondary infection with species of fungal pathogens (e. g. Alternaria) and premature dying of leaves.
Symptoms: Necrotic beet yellow virus (BYV): yellowing, later with small reddish necroses. Mixed infection of the two virus diseases are frequent.
Epidemiology: The virus is transmitted by aphids (the most important of which is the peach potato aphid Myzus persicae, or the black bean aphid Aphis fabae). The aphids absorb the viruses when feeding on infected plants. Virus sources may be goosefoot species (spinach, white goosefoot and orache), chickweed or volunteer beet and beet clamps.
Prerequisite: Mild winters and warm springs favour the survival and rapid spread of virus-transmitting aphids.
Risks: The aphids can survive in mild winters as adult forms, favourable spring weather. Resistance to insecticides, increased areas of oilseed rape, as oilseed rape serves as winter refuge.
Detection: ELISA test on leaf samples
Control: A direct control of the virus diseases is not possible. Indirect control can be carried out by chemical control of the vectors with approved insecticides. Pay attention to the advisory warning against aphids! The use of Imidachloprid as a seed treatment has significantly reduced the detrimental effect of this disease. In future resistant varieties may be the solution.

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