Board chairman John Loughlin said the reasons for Mr Sharp's resignation would remain confidential but his actions were not a direct problem for Zespri.
"However, they could have affected Zespri's moral authority on an issue and Ray decided to put Zespri and the industry first," he said.
Mr Loughlin said it was with sadness that he accepted Mr Sharp's resignation.
"Ray volunteered his resignation to me, after notifying the board of a potential conflict of interest related to his orchard activities.
"I know Ray remains a staunch supporter of the industry, retains the respect of fellow growers and will continue to add value to an industry he has such passion for," Mr Loughlin said.
Mr Sharp's position on the board would remain vacant until the annual meeting on July 18. While the remaining seven board members would have "to work a bit harder" to cover the vacancy, Mr Loughlin said there was little point in incurring the expense of an election so close to the annual meeting. Mr Sharp has been involved in the kiwifruit industry for 25 years.
"I remain committed to supporting Zespri and the wider kiwifruit industry as we emerge through the destruction caused by Psa and move toward a brighter future," his statement said.
Mr Sharp was a grower-director of Zespri, elected to the board in 2009. He also served on the Audit and Risk Management Committee and the Industry Advisory Council. He has a background in chartered accountancy.
He had been involved in the kiwifruit industry since 1995, starting out as an orchardist before becoming a grower director of post-harvest operator Eastpack in 1997. He is the chairman of EastPack. Mr Sharp was involved in governance, planning and the strategic direction of EastPack, and had significant interests in kiwifruit orchards in Opotiki and Tauranga.