One of Wellesbourne's principal investigators, who did not wish to be named, said a lack of job security meant scientists are looking elsewhere for work.
Although a consultation is being carried out by University of Warwick professor Tim Jones into the possibility of creating the industry-led centre, it will not be complete until after letters are received.
"Things are moving forward but it is the timetable that is a risk," warned the source. "We need to get something in place as soon as possible to stop people leaving."
Political support for a halt to the redundancies has grown, as former Defra minister Jane Kennedy last month laid an early day motion asking secretary of state Hilary Benn to intervene personally.
Conservative MP for Rugby and Kenilworth Jeremy Wright last week visited Wellesbourne and Lord John Taylor of Holbeach was due to meet Jones yesterday (8 April) to discuss the plans.
"The general election will come before any decision is made on this," explained Lord Taylor.
Horticultural Development Company chairman Neil Bragg said he was concerned about ongoing projects, given that lead scientists could lose their jobs.
"We have contracts that can theoretically run as far as 2012, but if a person leaves there is no guarantee that the work will continue. Within horticultural science there is great reliance on the individual and their expertise."