13 November 1998

Strobilurin fungicide use has clear variety effect

Strobilurin fungicides came

under scrutiny at a NIAB

workshop in Cambridge

and a BASF results meeting

in Scotland last week.

Andrew Swallow and

Allan Wright report

STROBILURIN yield boosts over conventional chemistry are consistent by variety, at least on this seasons results, says NIAB.

At five trial sites across the country consistent trends in wheat yield increases over a conventional fungicide programme were seen, ranging from just 0.77t/ha (0.3t/acre) in Spark to 1.61t/ha (0.65t/acre) in Equinox, says NIAB cereal pathologist Rosemary Bayles.

Barley shows a similar range of responses, from Pipkin at just 0.17t/ha (0.07t/acre) to 0.83t/ha (0.34t/acre) for Manitou.

"These responses over and above robust conventional triazole programmes are probably largely due to disease control. But the top varieties must be better able to respond to the greater green leaf area too," she says.

Diseases favoured by last summers conditions will have skewed the results, depending on how effectively a strobilurin controlled them and a varietys natural resistance. "Mildew was very low last year, but yellow rust was very high. Brown rust also affected 40% of the flag-leaf area on the most susceptible untreated variety. In barley, the strobilurins ability to control net blotch had a substantial effect."

At the lower end of the response scale, strobilurin use may need fine-tuning for economic returns, she says. "Perhaps on some varieties such as Spark there is a need to cut inputs to get the best of the new chemistry."

Dramatic changes to the NIAB list seem unlikely. "I do not think we will see varieties in a radically new light, or that there are varieties which have missed out on listing that would have made it if tested with strobilurins. There would be only minor changes in the ranking."

Using this data to produce mock recommended list would still leave Savannah with the top treated yield for wheat, but Equinox would jump up from fourth to second highest yielding. Consort slips from second to fifth place.

Plans to include strobilurins in the standard disease control programme for the UK Recommended List trials are under review. A gradual introduction is most likely, as with any other advance in fungicide technology, says NIABs head of cereals, John Ramsbottom.

NIABSTROBILURINWORK

&#8226 Equinox and Manitou gave biggest extra yield boost over conventional chemistry.

&#8226 Savannah still top yielding variety with strobs.

&#8226 First-year results only.

&#8226 Four strobilurin programmes compared with two robust conventional programmes.

&#8226 Consistent trends from national trials.

Average strobilurin yield

boost over conventional

chemistry (t/ha)

Wheat

Equinox 1.61

Buster 1.49

Riband 1.36

Brigadier 1.36

Savannah 1.18

Hereward 1.05

Rialto 1.02

Soissons 1.00

Consort 0.93

Spark 0.77

Barley

Manitou 0.83

Gleam 0.59

Angora 0.52

Regina 0.42

Jewel 0.36

Intro 0.32

Halcyon 0.30

Fighter 0.28

Fanfare 0.20

Pipkin 0.17

Average yield response of varieties to strobilurin programmes over and above a robust conventional programme. Based on one years results from five trial sites across the country. Trials funded by NIAB, HGCA, BASF and Zeneca.