Using an adjuvant with a pyrethroid insecticide can improve control of a key virus in potato crops by nearly 20%, according to Dutch research.

Potato viruses cost the UK potato seed sector an estimated £18m every year and farmers could reduce this loss by making a small change to spray programmes to control the aphids that spread the disease.

The UK’s 17,000ha of seed plantings is vulnerable to two major viruses within four weeks of planting – the potato leaf roll virus and the protyviruses, including potato virus Y.

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The findings from five years’ worth of trials using the Interagro adjuvant Banka, a specialist blend of alkyl pyrrolidones and polymers, showed an 18% increase in virus control 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.

“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,” reports Interagro’s product manager, Sarah Ferrie.

Zero tolerance

This is a big vulnerability for the sector, given that virus-free status of seed is fundamental to both the national and export markets.

The main vector is the peach potato aphid and growers must take a zero-tolerance approach to prevent virus transmission to avoid rejection by seed crop inspectors, she says.

The adjuvant is recommended 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.