Neonic Update

None of these will provide effective control of aphids.

Virus Yellows is a complex of 3 viruses; Beet Mild Yellowing Virus (BMYV) and Beet Chlorosis Virus (BChV) which are closely related, with the third virus being beet yellows (BYV). These viruses are transmitted when the aphid feeds, with the peach potato aphid (Myzus persicae) being the main concern.

The virus is carried into beet crops by winged aphids each spring and the most important aphid vector is Myzus persicae (the peach-potato aphid). Aphids, depending on the weather, over-winter on alternative hosts such as weeds and then migrate into beet crops. Other arable crops, such as potatoes or brassicas may also host the aphids. Other aphid species such as Macrosiphum euphorbiae (the potato aphid) and Aphis fabae (the black bean aphid) can transmit some or all of the yellowing viruses but are generally less efficient and therefore regarded as less important, especially when their populations are small. If virus-carrying aphids arrive in the crop, they can establish primary foci of virus infection. If aphids are not controlled these aphids and their progeny then cause secondary spread of the virus, leading to the classic yellow patches within fields. The viruses are not mechanically spread  and are not seed-borne.

Yes, this is important. Managing weed beet and controlling leaf growth on beet clamps, including any remaining waste after harvest, will help remove sources of infection for the aphids. Certain weed species are hosts for both aphids and some or all of the yellowing viruses.  Potato volunteers, as well as certain species of cover crops i.e. brassicas may also be sources of aphids that then may migrate to sugar beet.

The Virus Yellows Forecast will be issued annually in March. The BBRO use yellow-water-pan traps to monitor aphid numbers, in conjunction with a model that uses winter temperatures to predict the population growth of aphids in each factory area.  Aphids are then tested for virus to ascertain risk. This monitoring will be increased significantly ahead of the 2019 season, and regular updates on potential risk will be issued via the BBRO website, Advisory Bulletin and twitter. 

This will need to be closely monitored and will be dependant on the weather; a cold winter will provide some natural control on the aphid population.  Previous seed treatments may also have held aphid numbers in check, meaning we may be starting at with a low level aphid population. 

Monitoring shows that the UK sugar beet crop would have experienced seven virus epidemics of over 50% infection since 2000 without any effective control options such as the neonicotinoid seed treatments. In 13 of the last 17 years, these treatments have prevented economically significant crop losses due to virus yellows alone.

This depends on when the aphids are active and landing in crops.

Younger crops are more susceptible to infection. From about the 12-leaf stage onwards, plants become more resistant to virus. This is termed ‘mature plant resistance’. It is a gradual increase in resistance and not a quick ‘switch’ to full resistance. However, getting the crop to the 12-leaf stage as quickly as possible will minimise the susceptible phase of the crop. Good seed beds and establishment will be important.

 There is a lot of work looking at this but there is no current usable resistance in varieties in the  2019 RL list.

This depends on the virus, for BMYV and BChV it will take approx. 48 hours to become infected, once infected the aphid will carry the virus for life.  However, for BYV the virus is acquired within minutes, with the aphid carrying the infection for 2-3 days.

 This can vary but on average 2-4 weeks. Therefore, by the time you see symptoms it is too late to control the aphids.

You will see yellow patches in your field.  However, the symptoms of yellowing can be confused with many other symptoms such as drought and nutritional deficiencies. BBRO can test leaves to confirm the presence of virus. To access this free service please see the  Plant clinic.

This can vary considerably and depends on type and extent of infection.  Previous trials have shown yield losses of up to 30% with BMYV and up to 47% with BYV, per infected plant.

There are limited options. There are several pyrethroid sprays that can be used but aphid resistance to these is high. Additionally, pyrethroids will knock out the beneficial insects such as ladybirds and lacewings. These beneficial insects are particularly effective in controlling aphids. Therefore be very wary about using pyrethroid-based foliar sprays in sugar beet. A new non-pyrethroid spray has been approved for the control of aphids in sugar beet for 2019. The product name is Teppeki. The active chemical is flonicamid. Only one spray can be used in sugar beet. Teppeki has a persistence of up to 21 days, making timing critical.

The current aphid threshold for spray application is 1 green wingless aphid per 4 plants, with plants up to the 12 leaf stage.  BBRO will be monitoring both aphid numbers and the presence of virus in aphids as the season progresses. When threshold levels are reached, advice will be issued.

It is unlikely that this will provide effective control. Firstly, it is a carbamate and there is wide spread aphid resistance to this group of chemicals. Secondly, it is not persistent enough to control all but very early infestations of aphids.

This is an interesting strategy that BBRO is investigating but currently there is no clear advice that we can give regarding this approach or its effectiveness.

An interesting approach, but we have no clear information as yet.

The focus should be on seedbed quality not seed rates.  Ensuring that the seed germinates rapidly, and plants develop as quickly as possible to beyond the 12-leaf stage is the key.

BBRO has information on its website and provides regular Advisory Bulletins. Ahead of and during the 2019 season the BBRO will provide regular information from its aphid monitoring programme on the risk of virus and need for foliar insecticides.