27 November 1998

Race to combat take-all enters finishing stages

Plenty of new pesticides to

help growers combat pests

and diseases, plus a wealth

of technical advice, made

this years British Crop

protection Council

conference one of the best

for years. Charles Abel,

Brian Lovelidge and

Andrew Swallow report

over the next six pages

TAKE-ALL is under attack on two fronts and growers look set to be the main beneficiaries.

For several years Monsanto has been developing a novel seed treatment fungicide to combat the yield-sapping disease. Understand-ing of MON65500 is now well advanced, including indications of significant varietal interactions.

But competitors have been far from inactive. AgrEvo announced further details of its seed treatment fungicide Jockey, which controls take-all and foliar diseases.

Planned rates of Jockeys active ingredient fluquinconazole gave an average 9-11% yield increase in 50 European trials at a range of disease intensities.

But Jockey also provides foliar disease control, matching Rhone-Poulencs new seed treatment fungicide triticonazole for yellow and brown rust control and significantly outperforming established autumn product Baytan (fuberidazole + bitertanol), says AgrEvos Mannfred Wenz.

At the planned application rate of 75g per 100kg of seed Septoria control up to early ear emergence (GS51) is claimed to be as effective as a standard triazole spray applied at T1.

Complete control of bunt and loose smut is also claimed and efficacy against fusarium is achieved through a co-formulation with prochloraz.

"Fluquinconazole has no adverse effect on crop emergence or vigour, unlike Baytan, which reduced emergence by 7-11% in our trials," adds Dr Wenz.

Meanwhile, development of Monsantos MON65500 continues apace, with detailed studies at ADAS Rosemaund in Hereford-shire highlighting significant varietal interactions.

The HGCA-funded trials in 1994, 95 and 96 showed MON65500 boosted yield by an average 1t/ha in non-first wheat positions.

"But the average conceals a big effect of variety," says ADAS project leader, John Spink. Least responsive was Rialto, use of the seed treatment boosting yield by 0.53t/ha to 10.15t/ha in the third wheat slot. By comparison Brigadiers yield soared 1.35t/ha to 10.16t/ha.

That suggests variety choice will have a big influence on the value of using a take-all fungicide, says Mr Spink.

Rialtos relative lack of response is believed to stem from its earlier development, lower tiller production and higher build-up of yield-forming carbohydrate res-erves in the stem in late spring. &#42


&#8226 AgrEvos Jockey seed treatment hits take-all and foliar diseases. Available 1999?

&#8226 Monsantos MON65500 seed treatment shows clear varietal interactions. Available 2000?

Monsanto model

Monsanto is developing a take-all prediction model to help growers assess the risk to their wheat and predict yield recovery through use of MON65500. The model will also help growers decide whether to adapt their crop management by changing rotations, adjusting drilling date, or simply targeting inputs for optimum yield benefit. The model, which could be ready for use next year, is based on results from over 200 field trials over three years in France, Germany and the UK.