Grain contaminants are defined as those materials that make cereals unfit for either human or livestock consumption.
Contaminants can be physical, biological or chemical in nature. They can also be derived from a range of sources, including the environment as well as storage and processing equipment.
The Agricultural and Horticultural Development Board (AHDB) hosted a recent webinar for grain specialists, during which a review of the organisation’s current work on contaminants monitoring was delivered.
Grain contaminant
The backdrop to the event was the growing evidence that biological contaminants will become a greater challenge for the grain sector as the impact of climate change continues to build momentum.
Related to this is a possible change in contaminant standards which may well become a reality in the wake of a future plant health agreement between the UK and the EU.
AHDB’s grain contaminant survey is carried out in conjunction with a number of industry partners.
The work delivers an independent source of information regarding contaminant levels freshly harvested and stored UK grains.
All the data generated through the survey is publicly available.
Ergot
AHDB analysts recognise ergot as a specific challenge for the grain sector. It is a fungal pathogen that affects cereals.
There are several factors that can contribute to the risk of ergot. These include cereal type, weather conditions at flowering plus the impact of grass margins and grass weeds: including blackgrass.
Ergot is highly toxic when ingested by humans and livestock.
A recently completed review of ergot management practices by ADAS has allowed AHDB to issue new guidance to help farmers reduce disease pressure, limit crop infection and keep clean grain clean.
A number of key ergot management prevention strategies are recommended.
Reduce initial inoculum levels
Higher-impact interventions cover the strategic use of cultivations and drilling high-quality, clean seed (whether certified or home-saved).
Cultivations should aim to bury ergots to at least 5cm for at least one year.
Although ploughing is best for burial, any cultivation is more effective than direct drilling, according to AHDB.
Reduce infection risks
Growers are advised to include rotational adaptations, such as growing a non-cereal crop or a less susceptible cereal crop.
In order of decreasing susceptibility, these are: rye, triticale, wheat, barley, and oats.
Although information on varietal risk is limited, higher risk is associated with varieties that are open-flowering, flower for longer, or produce more late tillers.
Reduce secondary spread
Ergot affects a wide range of grass species, including blackgrass. As blackgrass flowers earlier than cereals, it is a key target for management.
The higher-impact interventions are based on integrated weed management approaches to reduce grass-weed pressures.
Careful management of high-risk fields or areas – such as headlands, tramlines and grass margins – will always be required.
It is particularly important to harvest infected areas separately and segregate contaminated grain from other grain.
Although it is possible to clean grain to some degree, it is not always completely effective, especially as some ergot fragments are extremely small.
The risk of ergot infection is especially high in wet seasons, so farmers should be be on the lookout for this pathogen when combining or buying grain for livestock feed.
Infected grain can make cattle seriously ill by constricting blood vessels and damaging the nervous system, resulting in seizures, loss of muscle strength, poor co-ordination, and – in severe cases – death.
