Aphid and virus management in potatoes
You can find information on aphid forecasting and monitoring tools on this page.
Aphid management Q&A
Why is this an issue now?
This may be an issue that has been building for a while and has now come to peoples’ awareness. Other potato growing areas such as the Netherlands (which implements a post-harvest testing regime) have experienced high levels of downgrades and failures due to virus. The specific reasons are currently not clear and so it isn’t possible to predict whether this is a one-off, seasonal effect or a longer-term trend.
Is this related to the banning of neonicotinoids meaning there are more aphids around?
The aphid yellow water trap scheme has been operating since 2004 and reports the numbers of aphids recorded in 100 traps per year. Although the location of the traps varies from year to year it’s probably a good data set to understand trends in aphid numbers. The counts don’t show a consistent trend across all aphid species.
Peach-potato aphid counts have increased since 2014 (the first season that neonicotinoid seed treatments were withdrawn on OSR) but the numbers fluctuate year to year.
Peach-potato aphid counts recorded from AHDB yellow water traps (2004-19)
Bird cherry-oat aphid counts haven’t tended to show a consistent increase over time. However, 2019 will be the first season that neonicotinoid seed treatments have been withdrawn for use on cereals in UK.
Bird cherry-oat aphid counts recorded from AHDB yellow water traps (2004-19)
Willow-carrot aphid counts have increased over time, except in 2018. The increase may be related to reports of reduced sensitivity to pyrethroids in this aphid
Willow-carrot aphid counts recorded from AHDB yellow water traps (2004-19)
What can I do differently in 2020 to minimise the risk to my crop?
Choose as high as possible grade of input seed. For seed crops burn down as soon as possible and monitor crops for any regrowth. New growth that develops after haulm destruction can be susceptible to aphid-borne infection especially when significant aphid pressure is still observed late in the growing season. Management of inoculum sources in ware crops and groundkeepers is very important in minimising the risk of virus spread. Ideally do not plant a variety which is high risk (e.g. lower grade/older generation/virus susceptible variety) near to higher grade production. Pay attention to store hygiene and clean and disinfect after store emptying to kill off overwintering aphids.
How do mineral oils work?
It is thought that mineral oils hinder the attachment of virus particles to the aphid’s mouthparts. While oil can lower PVY incidence in the field, the magnitude of control can vary considerably from year to year (the reduction was up to 2-fold in an AHDB-funded project on mineral oils). It’s likely that the variation is due to factors such as virus inoculum levels, aphid abundance and timing of the aphid flights into the crop relative to spray timings.
Are there issues with mineral oil use in GB?
Mineral oil treatment can alter plant physiology and, in some cases, be phytotoxic. This can have an adverse effect on the appearance of crops and there have been concerns that mineral oil use might affect seed crop inspectability. An AHDB Potatoes project on mineral oils addressed this issue and plots were established to study the effect of spray oil treatments on a range of virus-infected and healthy plants of various potato varieties. Phytotoxic symptoms (localised necrotic spots (see below) were occasionally observed. They tended to be observed when periods of sunny weather coincided with oil applications. Currently growers are advised that the use of mineral oils is at their own risk and if phytotoxic effects occur that affect inspectability the certifying authorities may refuse to grade the crop.
Representative pictures of the severity of leaf marking associated with mineral oil application (Trial plots at Cambridge, 2012)
Aphid forcasting and monitoring
Long-term (56 years in 2020) aphid data (from the suction-trap network) and weather data (Met Office and others) is used to forecast the date of the first aphid flights, as well as aphid abundance in spring and early summer.
You can sign up to be alerted to the first Peach Potato Aphid (Myzus persicae) found in a region or regions, and also when the index value in a region exceeds a given threshold (you have a choice of three thresholds). You can select the locations of traps you want to monitor by choosing from upto 8 regions.