Phytophthora survey

RHS project team
Dr. Geoff Denton
Dr. Simon Archer, Imperial College
Start date
01/01/2006 11:38:55
End date
31/12/2014 11:39:07
The problem

Phytophthora species are major pathogens of plants, with some species shown to infect more than 1,000 host plants. Recent identification of new Phytophthora species has shown the rapid spread of some species associated with the movement of plants.

Considering that private gardens in Britain cover about 270,000 hectares (667,000 acres), little research has dealt with the problem of Phytophthora in this habitat. Through the RHS Advisory Service around one-third of the plant disease enquiries answered deal with root problems.

We want to catalogue the Phytophthora species and host plants seen through the RHS Advisory Service. Information gathered can be used in many ways, such as helping to replant infected garden areas with less susceptible plants.

This will be the first survey to assess the impact, diversity and host range of Phytophthora species in UK gardens.


The plant pathologists deal with around 6,000 enquiries a year from gardens throughout the UK. The samples being surveyed come through the RHS Advisory Service and adition from the RHS gardens. All samples with typical symptoms for a Phytophthora infection are tested in detail.

If a positive result is confirmed then further laboratory work is carried out to identify the Phytophthora species. It is from these identified species that we are compiling our information. The information recorded include details of the location, host plant and Phytophthora species.

Benefits to gardeners

The study will provide information about the diversity of Phytophthora species in UK gardens as well as the susceptibility of host plants. Increasing knowledge about this pathogen will improve our advice to gardeners managing outbreaks in their own gardens.

Summary of results

The preliminary results have identified over 21 named Phytophthora species in UK gardens, with about 10 putative new species also identified. Over the four year study, confirmed Phytophthora cases were associated with 79 host families encompassing 150 genera. The top host plant record was Taxus and the top recorded species were Phytophthora cinnamomi and Phytophthora plurivora.

Further information

Comparison of techniques for the detection of Phytophthora survey
Pythium, a garden pathogen?

Advisory information

Phytophthora root rot

Phytophthora ramorum and P. kernoviae

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.