24 May 2002

Match spray mix to planned grain use

AN added complication when planning T3 spray mixes is the potential for fusarium mycotoxins to depress livestock performance, warns Richard Elliott of Bayer. There could be implications for human consumption markets too.

High mycotoxin levels can cause feed aversion, vomiting and haemorrhage, particularly in pigs and poultry. It is feared that low levels could have a lesser, but still significant, impact.

"There is no smoking gun to prove the link, but there is a strong implication that low levels can depress performance."

The EU is looking at limits for the key DON mycotoxin of 0.5ppm for retail products and 0.75ppm for grain for flour, with no blending permitted.

Peter Jenkinson, Harper Adams University College, confirms the need for caution. A recent survey of 300 UK grain samples showed 1.2% exceeded the EUs proposed DON limits, with 2.4% failing if all mycotoxins are considered.

Mr Elliotts advice is to adjust the T3 spray mix according to grain use. With no market premium for low mycotoxin feed grain a 50:50 strob/triazole mix is best. If home-feeding, particularly to pigs or poultry, use three-quarter rate anti-fusarium triazole and quarter rate strob.

Milling wheat and malting barley growers should do the same to avoid mycotoxins. "There is more testing going on than people realise," he says. By contrast seed crops should get at least 50% strob, because Microdochium nivale is the concern for establishment.

Even low levels of grain mycotoxins could lead to significant health effects, warns Hungarian fusarium expert Prof Akos Mesterhazy. Laboratory tests show mycotoxin levels of just 50ppb can render white blood cells 80% ineffective. Given their role in the human immune system, and the fact that such mycotoxin levels are commonly found in Hungarian flour, the issue needs investigating further, says Prof Mesterhazy.

Such medical findings could help explain the effects seen in pigs, which are significantly more sensitive to mycotoxins than humans, he adds.

Hungarian cereal farmers face a major fusarium problem mainly due to the predominance of Fusarium graminearum, a virulent form of the disease that produces very high levels of mycotoxins. Favoured by warm weather it is increasing in the UK. It can be particularly severe in crops following maize. Minimum tillage exacerbates the problem.

Hungarian wheat is visually checked for fusarium and can not be sold if it contains more than 2% infected grains. Each year 2-3% of crops fail. The export limit is 0.5ppm.

Resistant varieties could help in future, he says. Seven resistance genes have been identified, but introducing them into modern varieties is proving slow.