How to prevent white mold in silage bales?

Agriculture implies specific processes and, as you would expect,  factors that may compromise the quality of the crops can arise easily when climatic conditions vary. White mold is certainly one of the factors most feared by land workers. Today, there are measures being implemented to prevent its emergence and to prevent food from being affected.

In the following article, we will share valuable information about what causes white mold and how to prevent its presence in silage bales, in order to obtain forage with the best nutritional quality for dairy cattle and also horses.

When we talk about silage bales it is common to associate them with white mold, since their presence in stored forage is a latent threat. Farmers are always looking for innovative alternatives to help them prevent the presence of this fungus. The good news is that it is very easy to avoid white mold and thus, extend the useful life of forage if you follow certain guidelines.

Causes of the appearance of white mold and how to prevent it:

Knowing how to prevent white mold has its tricks. Many experts agree that its origin is due to the bad conditions in which the silage process is carried out, for example, allowing air to enter the bale or applying an insufficient number of film layers during the baling process. However, below we share some of the most frequent causes of white mold and what you can do to prevent it.

The importance of forage dry matter levels

One of the factors that most affects the growth of mold is when the crop is too mature, because when forage has been reaped after blooming or packed with a high content of dry matter -higher than 65%- the forage is more prone to develop mold, since it doesn’t present fermentation or there’s almost no fermentation at all. The lack of sugars in the plant, typical of overripe or very dry forage, doesn’t allow to obtain the lactic fermentation that lowers the acidity (the PH) of the silage, and therefore, acts as a preservative and inhibitor for mold formation.

The important thing is to ensile only good quality crops that guarantee at least 40-50% of dry matter. It is not recommended to exceed 60% of dry matter because we reach a very narrow margin of safety at these levels. It is also important that bales be dense and cylindrical. For that purpose, the previous baling process must be done with due care, in order to achieve a bundle with homogeneous shape, good symmetry and no bulging areas, since at wrapping time, an incorrect overlap of film layers on deformed areas can prevent the bale from maintaining proper air tightness.

Another factor of possible contamination that can favour the appearance of mold, is mowing a field of grass where corn was previously sown without removing all the remains before sowing the new forage. Fungi develops easily in these corn stalks, so it is common for them to be incorporated into the bales with fresh forage when the baler passes over them if those weren’t properly removed, thus contaminating with the spores the bales that are later wrapped.

Inadequate management of resources

In general, to prevent mold you must acquire good working habits and avoid bad wrapping practices that are sometimes done to save time. Frequently, instead of assuming their own mistakes, people tend to blame the materials used. Suppliers of wrapping machines as well as film manufacturers, have wrapping guides and instructions of use generally available, so it is advisable to dedicate the necessary time to dominate the art of forage conservation.

Whenever resources are properly exploited and managed, it is possible to create a microenvironment within the bale to avoid the appearance of fungi, giving preference to the lactic acid generating bacteria, that is essential for optimum fermentation, which ultimately help to keep the forage preserved. This is the only way to guarantee the quality of the products.

Choosing a plastic film with the necessary resistance

When air manages to penetrate the silage bale the result will be no other than the production of white mold. In this case, the farmer probably used a film without the level of resistance required for the type of crop that he wished to protect.

Currently, there are different types of specific stretch film in the market to cover all types of uses. There is 5-ply standard film to wrap normal forages, usually in cylindrical bales. There are also high-performance films with 5 and 7 layers, for the same application but providing more footage per roll. These offer greater autonomy when wrapping and at the same time reduce the cost of wrapping by bale.

You can also choose super quality films, which are designed to withstand wrapping under extreme conditions, as it usually happens with the combination of temperature factors, square bales, diverse types of manipulation, hardness of certain forage such as alfalfa, high speed wrapping machines, etc.

Given all the above, it is advisable to know in advance the type of crop that will be wrapped, the conditions under which the work will be performed, the type of wrapping machine that will be used, etc. and adapt the type of film to the conditions of each case.

As a basic rule, the recommendation is to always apply at least 6 layers of overlapping film on the bales to obtain optimum sealing. In this case, a film with a good content of adhesive will always be the best option, since air is able to penetrate the bales and reach the layers of the film, especially when the content of the adhesive agent used in its manufacture is poor.

Also, the film must be applied with the proper pre-stretching tension to ensure that the bales are tight and a better barrier to the gases is formed.

Air oxygen is the greatest enemy of good forage conservation. Any perforation or tearing on the surface of the bales that can create a pore or hole, that would therefore allow an air access route to the inside of the bale, must be detected and sealed as soon as possible.

The air that penetrates inside makes the fermentation process degrade into an aerobic phase by rapidly increasing  the development of damaging mold. We invite you to read our article about oxygen barrier films with very interesting information about this.

In sum, remember that to avoid white mold and achieve forage with optimal nutritional power, you must pack dense bales with properly mature forage and dry matter, and to avoid air inlets, apply a minimum of 6 layers of overlapping film and use silage films of quality contrasted and adapted to the conditions under which you will apply the wrapping.