White mould – causes and prevention
During the silage season the bpi.agri team regularly visits farmers and contractors across the country to answer any technical questions or queries they may have about the use and application of Silotite bale wrap. One topic they are regularly called out to discuss is the prevention of white mould.
Roger Jackson, bpi.agri’s Area Manager in the South West has made a few such visits in previous seasons. “White mould appears when the conditions are not right to produce silage” says Roger. “In order to produce high quality silage, a number of factors have to be considered, including the dry matter content and quality of the crop being baled, and your choice of balewrap, which can influence the seal achieved around the bale. Upon investigating each incident of white mould I have found that it could have been prevented by making sure that all the key elements were in place to allow the silage to ferment to perfection.”
Roger explains that there are a number of things it is essential to get right during the wrapping process. The grass must not be over-mature or too dry when it is baled. If the grass is too dry and/or over mature and stemmy, the risk of mould growth increases due to insufficient or non-existent fermentation.
For silage aim for 30-50% dry matter (DM)and for haylage 50-60% DM. As DM levels increase from 60% towards that of hay (around 85%), so in turn do the risks of mould growth, due to poor fermentation. It is therefore advisable to limit dry matter to a maximum of 60%.
Another possible cause of white mould is air entering the bale and on several visits Roger has found that not enough layers of Silotite were applied during wrapping. Alongside all the other influencing factors, the choice of a high quality balewrap and its correct application will help prevent mould growth by preventing the ingress of air into the bale. It is essential, therefore, in creating an air barrier, to apply sufficient layers of balewarp. For DM levels up to 50%, an absolute minimum four layers of bale wrap should be applied to all areas of each bale, 6 layers being the minimum where DM is higher. However, research completed by IGER during 2005 found that applying 6 layers of black film to conventional silage bales significantly reduced the incidence of mould in the bales compared with applying just 4 layers and produced marked economic benefits. This confirmed bpi.agri’s experiences over the past 20 years and that of numerous contractors who have adopted the 6-layer format as standard practice.
By and large, the most common cause of white mould is poor practice. Whenever it appears, most people are too quick to blame the wrap – perhaps because it is the most visible part of the process (unlike the less tangible elements of bacteria or air). The wrap however is merely a tool and like any tool it needs to be used correctly to deliver the best results. Part of this correct usage entails ensuring all the other basics have been satisfactorily considered and taken care of.
Ultimately when it comes to balewrapping and the production of quality silage devoid of white mould, one old maxim seems to ring true – that you need to start right to end right.
For further information or advice please contact the Silotite team on freefone 0800 0320 640 where one of the team will be pleased to help. Alternatively visit www.bpi.agri.com/downloads where you can download the bpi.agri Contractor Handbook which contains the ‘Top 10 tips’ for successful bale wrapping.
DATE: 06/06/2007
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