IT departments are failing to address an applications "black hole" with IT managers in the dark about software usage and cost.

That is according to research commissioned by Fujitsu, which shows that the complexity of applications estates means IT managers don't know about costly redundant applications lingering within their organisations.

Fujitsu says any IT departments are failing to get to grips with this issue, running either "inadequate or ad hoc audits" of applications and "not acting on their findings in an appropriate and timely way".

The research, completed by Vanson Bourne, saw 100 UK CIOs and IT managers at large firms questioned. They all worked at firms employing over 1,000.

Of these, only 47 percent of organisations audited their applications estate. The research found that 42 percent said it would be "difficult" or "very difficult" to make a decision over decommissioning applications. Only 4 percent said it would be "very easy".

Mergers and acquisitions are adding to the complexity, showed the research. More than half (57 percent) of all organisations surveyed had undergone some form of merger over the past two years, and over half (56 percent) found it hard to get hold of information to evaluate the combined applications estate.

Before any merger, 78 percent claimed they knew about the state of most or all applications and systems used across their organisation. But post-merger only 12 percent said they had an accurate understanding of which applications were used within each organisation.

Organisations are also reluctant to act on the results of an audit, with just 15 percent saying they would immediately remove applications which are identified as redundant.

And 20-25 percent rarely or never remove redundant applications, even after identifying they are no longer in use.

John Hanley, managing director of the applications division at Fujitsu UK & Ireland, said, “There is no doubt that applications rationalisation is an area which can deliver cost savings and help organisations to reduce their IT spend. Simply not knowing the state of your applications portfolio is clearly not a viable option."