As has been well documented previously, the correct storage of silage bales is vital to preserve and retain the quality and nutritional value of the feed inside. Handling and storing bales properly avoids damage caused by birds and rodents or even grass stubble. However, there is another potential hazard to baled silage, which has until now been overlooked, and that is the damage which can be caused by wireworms.
Wireworms are the larvae of click beetles and are usually found in permanent pasture. Damage caused by them has traditionally been associated with crops following long-term grassland. In recent years, wireworm damage has become an increasing problem for potato growers in the UK. As soil dwellers, they bite through roots and stems at ground level and any baled silage stored on the ground could be at risk of attack.
Visible wireworm damage takes the form of 4mm diameter holes created by the worms as they enter the bale. If farmers wish to store bales on grassland, it is possible to do so as long as the bales are kept at least 10 metres away from any water, including field drains and ditches into which silage effluent could enter. However, storing bales on grassland could lead to plastic film wrap which is in direct contact with the soil being damaged by burrowing wireworms.
In 2007, Dow Europe GmbH, manufacturer of DOWLEX‰ Polyethylene Resins designed for bale wrapping films, and bpi.agri, manufacturers of Silotite, both independently commissioned baled silage trials at the Institute of Grassland and Environmental Research (IGER). The test bales from both of these trials were stored on grass at the IGER farm. Upon inspection during the autumn, Rhun Fychan, IGER Silage Researcher, found the bales to be damaged when they were opened. Up to 10% of the silage surface was found to be mouldy and at first it was thought that the holes in the silage film were due to mechanical damage by the rollers of the bale handler. However, a closer inspection identified that the holes had been caused by wireworms.
Norbert Schulze, Silage Marketing Manager at Dow Europe GmbH, pointed out that: "Although no case of damage to baled silage stacks by wireworms had been previously reported and that this was perhaps a rare occurrence, farmers need to be aware of the possibility of this type of damage when choosing their silage storage area."
Following the discovery, the damage was assessed by Peter Dennis, an ecologist at Aberystwyth University. Mr. Dennis is in no doubt that the damage was caused by wireworms as it is similar to damage observed previously on sugar beet.
Louise Yates, Marketing Manager at bpi.agri, commented: "We are disappointed that the trial bales have been affected by wireworm attack which has been a growing problem in other areas of UK agriculture. However, it is important to let others know of our experience so that they are aware of this potential hazard."
IGER recommends that farmers check their bale stacks as they feed this winter assessing the silage stretch film for wireworm damage in the areas where it occurs i.e. around the periphery of where the bale touches the ground. Wireworm damage will not be an issue on hard standing areas so if any such problems are identified it is worth considering moving the bales to this type of storage area where possible.
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All enquiries to Dr David Davies, Senior Research Scientist/Agricultural Outreach Manager, Institute of Grassland and Environmental Research (IGER)
E-mail: david.davies@bbsrc.ac.uk Tel: 01970 823000
Notes to Editors:
The Institute of Grassland and Environmental Research (IGER) conducts research programmes focusing on grassland-related sustainable agriculture. Research includes studies on soils, plants, animals and micro-organisms and their interactions, and ranges in scale from molecules to landscape.
