26 June 1998

Lodging not down to strobilurins

50 years work to help

improve arable farm

businesses was celebrated

at ADAS Boxworth last

week. Andrew Blake listened

to some topical messages

STROBILURIN fungicides are not responsible for the lodging now showing up in many wheat crops, and growers ignoring them could lose out, according to disease specialist Bill Clark.

He dismisses fears that apparently lush green stands resulting from strob applications are more lodging prone than those treated with triazoles alone. Indeed signs are that one of the novel products, Amistar (azoxystrobin), may well help counter flat crops.

Trials at Terrington, Norfolk, last year showed that although another strob product, kresoxim-methyl-based Landmark, kept the crop greener for longer than triazole Opus (epoxiconazole), lodging levels were similar, he notes. "But it seemed Amistar could have a significant effect in terms of reducing lodging," Even where the crop received a well over-optimum nitrogen dressing of 340kg/ha (272 units/acre) the Amistar treated plots remained standing.

"To some extent that is the opposite of what we might imagine because, unlike the triazole, Amistar has no growth regulation effect." Mr Clark believes better rooting linked to the obvious above-ground greening could be the explanation. "It is a free extra potential benefit."

Growers unwilling to give the new profit-boosting products a try could soon find themselves left behind, he warns. Those questioning the expense with wheat at only £70/t should instead examine their cost-effectiveness. Even at that low grain price and current fungicide costs the new materials can add £120/ha (£40/acre) to the bottom line when used correctly, he calculates. "It is certainly over £100/ha."

Producers relying on triazole technology alone may achieve full disease control but will deny themselves the strobs yield enhancing effects, he explains. "It is the icing on the cake. They will have to get into this new technology or be stuck on a yield and profitability plateau."

Mr Clarks only caveat is that the strobs demand better management. "They are technically more difficult to use. If you just throw them at the crop you wont get the best out of them. A lot of people used Amistar on its own this year and it was a disaster where they got the timing wrong."

He also refutes the idea that the full benefits can be obtained by topping up a triazole-based programme with a low dose of a strob late in the season.

Mr Clark describes Amistar and Landmark as the equivalent of sulphur and mancozeb in the 1960s. Other more promising strob products, perhaps with disease eradicant activity, should be available within three years. &#42

Wheat on its way down but strobilurins not to blame, says Bill Clark.