The UK seed potato sector loses an estimated £18m from potato viruses annually, a cost that could be dramatically reduced by one small change to spray programmes, according to research and commercial trials conducted in The Netherlands.
The findings from five years’ worth of trials with an Interagro adjuvant called Banka, has shown an increase in virus control of 18% when applied with a pyrethroid insecticide up to, and including, tuber initiation. The work, conducted by Holland Fyto, also recorded an average improvement in potato yields of 0.89t/ha which translates into an estimated margin gain of £178/ha*.
With resistance to pyrethroid insecticides now widespread, coupled with the succession of relatively mild winters encouraging survival of a higher number of aphids, the need for some positive news is likely to be highly welcome.
The UK’s 17kha of seed plantings is vulnerable to two key viruses within four weeks of planting, both are transmitted by aphids – Potato Leaf Roll Virus (PLRV) and the Protyviruses, including Potato Virus Y (PVY). This is a big vulnerability for the sector, given that virus-free status of seed is fundamental to both the national and export markets. PVYN (veinal necrosis strain) and recombinant PVYNTN (N-tuber necrosis) are key viruses for both UK and The Netherlands with the peach potato aphid being the major aphid vector – just one “drill” for a few minutes, and the job is done. Growers must take a zero-tolerance approach to prevent virus transmission to avoid rejection by seed crop inspectors.
The Dutch Banka trials clearly showed a reliable improvement in virus control from the addition of Banka in each of the 5 years tested and demonstrated improved reliability over mineral oils, excellent crop safety and improved rainfastness of 30 minutes, helping to maintain tight spray intervals in marginal weather, reports Interagro’s Product Manager, Sarah Ferrie. “The trials also logged a tuber number gain with Banka, versus a substantial loss using mineral oil Olie-H, not currently registered here in the UK.
“Growers involved in Holland Fyto’s commercial trials observed that crops treated with Banka were more resistant to haulm collapse following torrential rain, a disadvantage typically experienced when using high dose mineral oil. Growers really appreciated the very low dose, 0.1% v/v Banka versus 2.1% Olie-H. At a water volume of 300 l/ha, that means the grower applies 0.3 l/ha Banka versus 6.25 l/ha mineral oil and is therefore much more efficient for growers.”
Practically, Ms Ferrie thinks Banka is a good fit for UK growers. “Where crops are at high risk of virus transmission, mineral oil may be added to the insecticide to improve coverage, but they clearly have disadvantages. Banka delivers reliable and crop safe improvement in pyrethroid efficacy.
We recommend Banka for application in tank-mix with all leading potato pyrethroid insecticides and fungicides at inclusion rates of just 0.075-0.1% by volume up to and including tuber initiation.
The Holland Fyto trials were based on treatments applied at 80% crop emergence with Sumicidin Super (25g/l esfenvalerate), applied weekly over 10 weeks in a mancozeb-free programme. All applications were made using a 75% drift-reduction nozzle, the Teejet Airmix 110-04. Water volumes were 300l/ha and the crop had 100% PVY infection in the two outer rows.
Banka is an adjuvant manufactured by Interagro using a specialist blend of alkyl pyrrolidones and polymers.