Monsanto discovers chemical that deals with cereal disease

The cereal disease "Take-all" is suitably named, given the extent of damage to wheat and barley it brings every year

The cereal disease "Take-all" is suitably named, given the extent of damage to wheat and barley it brings every year. The distinctive white heads and black roots in plants can often signal plant losses of up to 50 per cent in the Irish climate, and average at more than 5 per cent for Europe once the fungus Gaeumannomyces grammis takes hold.

It was called Take-all after the devastation it caused to the Australian wheat harvest in 1852. The disease restricts both water and nutrient uptake and predisposes the crop to stress, decline and, ultimately, death.

With no known chemical control and a growing toll every year, the US company went in search of a treatment. It was motivated by Take-all being one of the key reasons why subsequent cereal crops have a lower yield. Thus in Ireland, for example, where cereal options are not as good as in other climates, a high degree of crop rotation is demanded and, in many instances, farmers have no choice but to get out of cereals.

It was a process of intensive screening during the 1980s that uncovered "a new area of fungicide chemistry", recalled Dr Patrick O'Reilly, Monsanto's business manager in Ireland, who was involved from the beginning in the development of the new fungicide, now traded as Latitude.

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Such is the threat of Take-all, that it is "the only disease that has a direct bearing on which crop he will grow next year".

The first active molecule with the ability to control Take-all was discovered in 1988, signalling intensive interest in benzamide chemistry. The active ingredient is the silicon-based compound silthiopham, with is radically different to the vast majority of fungicides in use.

The amazing thing is its exact mode of action is not yet known but 50 trials in six countries (including Ireland) over five years have confirmed a high degree of specificity; i.e. it only affects Take-all fungus.

Monsanto research is investigating the possible mode of action intensively, in addition to pursuing a search for a gene that might confer resistance to the disease in a genetically modified cereal variety. It is also working on biological methods of control. Latitude is best used as a dressing on seeds, Dr O'Reilly added.

The chemical has a "no hazard" label classification, a rating based on its potential impact on wild bird populations and other wildlife.

Equally important, it does not interfere with the build-up of soil microbes which build-up resistance to the disease.

Recent surveys in Ireland have shown that 38 per cent of growers are deterred from growing more wheat due to the risk of Take-all, which is an indicator of the fungicides potential within the Irish context. Put another way, explained Mr Jerry Steiner of Monsanto, only 580,000 tonnes of wheat will be grown here this year, and Ireland will have to import 500,000 tonnes.

The US company may have chosen Ireland for the global launch of Latitude (because of so much of its research being based here and product registration was secured here first), but it believes it will have a global impact and will help to make up a colossal wheat deficit which will become even more pronounced throughout the world, driven mainly by population growth.

Restrictions on land-use due to phosphate/nitrate pollution problems and capacity difficulties will limit options while, Monsanto believes, GM wheat-production will not be sufficiently big to fill in the gap.

What's more, it is insisting that Latitude facilitates making up that difference in a sustainable way.