Less than three weeks after denying rumours that Chief Financial Officer Michael Panteli was about to sling his hook Plant Impact announced that the crop productivity firm's chief bean counter has resigned with immediate effect.Robert Stafford has joined the company as interim Financial Director with immediate effect, but will not join the board. Stafford currently serves as Managing Director of Stafford & Co. Chartered Accountants, a financial and accounts advisory firm based in the Manchester region. Plant Impact is looking for a permanent replacement for Panteli.Meanwhile, the company's flagship partner, Japanese agricultural chemicals giant Arysta LifeScience, has agreed to amend the terms of the agreement between the two companies over the exclusive worldwide licence to manufacture and sell BugOil, Plant Impact's ecologically friendly insect and mite repellent.The value of the remaining regulatory milestone payments potentially due to Plant Impact has been reduced in return for extending the repayment date for the £750,000 development loan from Arysta to 31 May 2013.The Plant Impact board believes that these amendments improve the financial position and cash flow outlook of the company and are likely to be neutral to the current carrying value of BugOil on the balance sheet.Shares in Plant Impact rose a quarter of a penny to 17.25p on news of the revised agreement with Arysta.