- Lead scientist
- Geoff Denton
- Start date
- 2008
- End date
- 2013
- Keywords
Phytophthora, Pythium, Survey, Pathogen, Pathogenicity, UK Gardens, RHS Advisory Service, Damping Off
- Benefits to gardeners
This project is to evaluate the possible impact to gardens and garden plants from the presence of Pythium species.
As more new Phytophthora species are being identified as major pathogens of ornamental plants the impact of the closely-related genus Pythium within gardens is relatively unknown. Our research will benefit gardeners by establishing the diversity of Pythium species and potential to cause major damage to ornamental plants.
- The problem
The RHS researches Phytophthora, a known plant pathogen with a wide host range, of which there are around 100 known species. Pythium, closely related to Phytophthora, has more than 150 species recorded, but they are not all plant pathogens like Phytophthora species. Some are free living in the soil and water, whereas others are pathogenic with Pythium species known to infect animals, fungi and plants.
Through the Phytophthora research, large numbers of Pythium species have been identified coming from dead or dying plants and in the absence of other pathogenic fungi. Much is written about Pythium species involvement in damping off of seedlings and causing damage to commercial plants via irrigation systems.
This study will investigate the pathogenicity of Pythium species towards mature plants and their prevalence within UK gardens.
- Approach
To understand the diversity of Pythium species within UK gardens a survey was initiated. Symptoms caused by Pythium species are similar to those caused by Phytophthora species. So plants received through the RHS advisory service with typical indications of a Phytophthora infection, foliar dieback, stem lesions or blackening of the roots, were additionally tested for the presence of any Pythium species.
The detection methods for Pythium species from samples received through the RHS advisory service were;
- Detection using nested PCR. Detection of a specific region of Pythium DNA followed by identification through sequencing
- Recovering a live culture of Pythium, using seeds as a bait. Live cultures are recovered and identified through sequencing the Pythium DNA
Culture, or isolates, will then to be used to inoculate host plant to check aggressiveness. This work is currently ongoing.
From our preliminary results we have identified 17 Pythium species in UK gardens. During 2006 and 2007 alone we recorded 72 different host genera. Our top host plants that we record are Taxus, Prunus, Rubus and Cornus.
Pythium sp. is the highest recorded due to being able to narrow it down to a genus but not to species level. Our top Pythium identified to species are Pythium intermedium and Pythium sylvaticum.
The majority of the Pythium species being identified are known pathogens of plants, and records have them associated with damage to seedlings. Further work will also look at improving our methods for identification to species level.
- Further information
Read more on Phytophthora bleeding canker
Advice on damping off
Phytophthora ramorum and P. kernoviae
Read about the comparison of techniques for Phytophthora detection
Read the studies on the pathogenicity Phytophthora and Pythium on yew (Taxus baccata)
Read the Phytophthora survey