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Protecting Your Bales From White Mould

Preventing White Mould in Round Bale Silage

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The use of modern mowing and bale wrapping equipment means round bale silage is a preferred means of preserving grass.

Making quality bales is vital and good round bale silage can easily be spoiled by an onset of white mould. In order to prevent this, a number of factors should be considered. Some good rules of practice will benefit in the long run - blaming the quality of the wrap rarely the answer!

Primarily the dry matter content and the quality of the crop are key – these two elements are essential to create the perfect environment within the bale for the bacteria to successfully do their job.

Ideally aim for 30-50% dry matter (DM), anything over 60% will put the fermentation process at risk. Over mature forage at harvest, dead material from the base of the sward, weed infested grasses and contaminated soil can all lead to white mould developing. Combine this with high oxygen levels - poor bale density and incorrectly wrapped bales and the bacteria will undertake a different process to the one required.

Insufficient layers of wrap will allow oxygen to get into the bale, therefore, each bale should be wrapped a minimum of four times or preferably six. Bales with a DM percentage of over 50% must be wrapped with six layers, giving a better sealing of the crop and will in turn be stronger when handling.

Aim to wrap the bales at the stacking point (on hard standing is best). This will prevent unnecessary handling and potential damage caused by field stubble and in transport. Bales that have puncture holes or damaged when handling will expose the silage to the air; keep an eye out for splits or semi-opaque strips which may indicate an insufficiently wrapped bale.


Black wrap is still predominantly used in the UK – you may want to consider a lighter wrap. Paler coloured wraps are heat-reflective and could prevent the development of spoiler organisms. Bird and vermin damage will occur if the bales are not netted, so netting the stack is vital.

The most common cause of white mould is poor practice, so a combination of preparation and good practice will help you maximise your bale stack and prevent loss next season.


For more information on crop packaging call Nigel Cockwill on 07786 855223.

Source Details

 625 Mole Valley Farmers Newsletter

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