The latest PSD report has been published this week in light of the EU pesticides legislation's second reading amendments agreed by the European Parliament's environment committee.
The revised PSD report on the impacts of the EU proposals for new pesticides regulations can be downloaded here:
PSD has looked at 278 substances as part of its new impact assessment and concluded that 14-23% could be lost as a result of the proposals.
The report states: "It is clear it is not simply the percentage or absolute number of substances that might be lost which is the most important factor, but the particular substances concerned."
PSD is now working on a report that will outline the impacts for conventional crop production in the UK.
It is expected to be released in the next week.
National Farmers Union (NFU) plant health adviser Paul Chambers said: "In terms of herbicides, horticulture will still be hard hit.
"It depends what substances are lost, not the figures."
Crop Protection Association chief executive Dominic Dyer said: "We remain deeply concerned about the impact of these proposals.
"We continue to call on the UK Government to seek agreement with other member states to include a safeguard clause in the final regulation, setting up a council work group to carry out a full EU-wide assessment on this legislation before it comes into law."