Rust Spotters Needed

posted on May 24, 2012
RHS logo

Visit the RHS website pear rust page

Sylva has teamed up with the UK’s leading gardening charity, the Royal Horticultural Society, to launch the 2012 pear rust survey under our TreeWatch initiative.

The Royal Horticultural Society (RHS) is working with the Sylva Foundation to run a survey in the TreeWatch initiative to map the incidences of European pear rust across the country. Over the last ten years the RHS Advisory Service has seen a steady increase in enquiries suggesting that the fungus is spreading and gardeners are becoming more concerned about its effects.

Both charities are encouraging gardeners to get involved with this survey which is being run between May and September. Anyone wanting to help or provide information can visit: or send samples to the RHS Advisory Service.

European pear rust is a disease caused by the fungus Gymnosporangium sabinae. Like many rusts, it needs two hosts to complete its life cycle. It causes striking orange spots on pear leaves during summer. Junipers are the second host and infected plants produce orange, jelly-like, horn-like outgrowths in spring which produce spores.

“We are keen for gardeners to get involved with this survey because we need to find out why the fungus is increasing in frequency,” says John David, RHS Acting Head of Science. “Having better records will help us understand the biology behind this fungus and therefore in turn hopefully how to control it.”

Chief Executive of Sylva, Dr Gabriel Hemery, says “We are delighted to be working with the RHS again this year to support this important survey. With an increasing number of pests and pathogens impacting the health of our trees, the power of the citizen scientist is coming to the fore. Our collaboration during 2011 resulted in some important data that has now been shared with the National Biodiversity Network: the first time that disease data has been shared with this important national resource.”

Download the Press Release


  1. […] spotters needed SYLVA • reviving our wood culture __________________ "I willingly confess to so great a partiality for trees as tempts me to […]

    Pingback by Rust spotters needed - | Discussion Forum for Arborists — May 25, 2012 @ 7:58 pm

  2. I have a Conference pear tree in my garden which has all at once lost all its pears and leaves are dying also the same thing has happened to my Cheery tree which is now totally clear of any leaves.

    Comment by john payne — June 8, 2012 @ 10:26 am

  3. We have an old pear tree (at least 50 years) which has rarely produced any decent fruit in the last twenty years (last year was a wonderful exception). This year, it appears to have no fruit at all. In mid-June, the leaves are so severely affected by rust, the entire crown is a deep gold. Our Cambridge gardens are extensive and we have do some Juniper trees, which are yet to be inspected.

    Re previous comment, I don’t know if there is any connection but we have lost a prunus this winter too, a young but well established ornamental tree.

    The RHS website asks for volunteer information but it’s not obvious to me how to provide this (where is the box or tab?!) other than through this blog.

    Comment by Elena Moses — June 20, 2012 @ 12:09 pm

  4. Thanks for your interest in TreeWatch Elena.

    Visit where you will (hopefully) find all the information you need.

    Comment by Sylva Foundation — June 20, 2012 @ 12:12 pm

  5. I planted a conference pear tree a year ago about 3 metres from a 27-year-old prostate juniper. During recent years the juniper has had a jelly-like fungus on the stems in spring which I was not able to identify. Last year the pear yielded 6 pears and started to develop a few rust spots on the leaves. This year the spots are much more extensive and there was no pear blossom. When I visited the RHS website recently I was at last able to find what was wrong.
    The juniper does not look well this year and will be removed.
    We have a medium-sized garden on the outskirts of Redditch, in Worcestershire.

    Comment by Rosie Frizzelle — July 25, 2012 @ 10:34 am

  6. I purchased as small (patio) pear tree last year and this has developed pear rust as illustrated in the RHS Journal. Not sure what to do next as we ant to avoid using chemicals as an eradicator.
    John Bennett

    Comment by John Bennett — August 7, 2012 @ 1:01 pm

  7. Should have added the site is in Harpenden!

    Comment by John Bennett — August 7, 2012 @ 1:02 pm

  8. I live in Bushey, Herts, & I have a Conference Pear Tree at least 40 yrs old and 2/3 years ago I noticed orange spots on the upper leaf surface & growths from the lower leaf surface. I took the leaf to a garden centre who were unsure what it was but recommended spraying with a Bordeaux mixture, which I did early the following spring. Last year I had a good crop of pears but noticed the odd leaf was infected. This year I have had no pears at all and all the leaves are infected & dropping off, and the tree looks vey sick.

    Comment by Ken Baines — August 20, 2012 @ 10:34 am

  9. Hi

    I have pear rust but it is much less than last year. One lone tree is clear this year. The leaves are not affected but I had an almost zero crop due to a late frost. I live in Surrey.

    Comment by Louis Wikes — September 27, 2012 @ 4:03 pm

  10. Hello. To complete the survey on your tree take the following steps
    Log in to
    Click on surveys
    Choose the Pear Rust survey page
    Click on the ‘my trees’ tab
    Your tree(s) should appear on the right of the map. Click on it’s name.
    This will bring up below the information you need to update its status.
    When done, click ‘save’

    Any feedback is always appreciated

    Comment by Sylva Foundation — September 27, 2012 @ 4:09 pm

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