Pear rust - huge tree affected
EmilyJEG
Posts: 10
My Nana has a huge pear tree in her back garden. I don't know how long it's been there but it's the height of a house and branches out across a fairly large area.
We were visiting this weekend and my husband noticed that the leaves had spots on them with disgusting looking growths on the back. A bit of Googling and I've discovered it's called pear rust.
As far as I could see, the entire tree was affected by it.
Is there anything that can be done? Does the tree need chopping down, or is it safe to stay? Is the disease harmful in any way to humans? I have two young children and don't want them to have any problems if they happen to pick up a leaf, and I also don't want the tree to fall on my Nana's house if it's likely to have been damaged by the disease - the tree is so large that it'd destroy a substantial amount of her home!
Thanks 
Posts
HELLO EMILY.
FIRSTLY, PEAR RUST IS NOT DANGEROUS TO HUMANS. AT ALL.
SECONDLY, IT ISN'T REALLY EVEN DANGEROUS TO PEAR TREES.
IT IS A FUNGUS.
SO THINK OF IT AS SOMETHING LIKE ATHLETE'S FOOT FOR TREES. THEY CATCH IT FROM ANOTHER TREE (IN THE CASE OF PEAR RUST THE OTHER TREE IS A JUNIPER TREE). LIKE ATHLETE'S FOOT IT IS ALMOST IMPOSSIBLE TO ERADICATE ONCE YOU HAVE IT. IT IS JUST A VERY ANNOYING THING THAT YOU LEARN TO LIVE WITH.
THE PEAR TREE GETS ORANGE SPOTS AND LUMPY GROWTHS ON ITS LEAVES. THESE FALL TO THE GROUND. THE FUNGUS THEN FLIES AWAY ON THE WIND TO FIND A JUNIPER TREE. THE JUNIPER TREE GROWS A DIFFERENT TYPE OF KNOBBLY WART. THIS EXPLODES WHEN IT FEELS THE TIME IS RIGHT AND RELEASES MORE SPORES WHICH FLY OFF IN THE WIND TO FIND A PEAR TREE.
FOLLOWING STILL?
THERE IS NO CURE. THE ONLY THING YOU CAN DO IS SWEEP UP AND BURN THE LEAVES THAT FALL OFF YOUR TREE.
If you live in Derbyshire, as I do.
No problem for us, thankfully (that'd be nasty, coming out in orange pustules!), but the tree needs some management. Clear up all the diseased leaves as they fall. I appreciate if it's a big tree you can't go picking off affected leaves. Ideally burn those leaves, or dispose where they won't come back near your tree! There's little available to combat the rust once it's got a hold except good hygiene each year. It's been bad this year because of the humid conditions recently. Preventative sprays are an option (and are only that, not a cure), but on big trees it is obviously an awkward task.
H-C
Pansyface - snap! Nice analogy!
H-C
Hi Emily,
You have already had some excellent advice from pansyface and H-C, so I have nothing more to add except that the Royal Horticultural Society are currently running an online pear rust survey, in order to improve knowledge of the known distribution of the fungus across the UK.
It is a very simple to complete, just visit the pear rust page on the RHS website www.rhs.org.uk/advice/profile?pid=236 and follow the survey link.
pbff
p.s. a brilliant anthology, pansyface! You have the gift of teaching, that much is clear
It's doubtful how much difference removing the infected leaves would make, since the spores from these will infect juniper rather than reinfecting the pear. The RHS page does say: Removal of leaves on heavily infected trees may cause more harm than good. Removing any junipers nearby or at least pruning out infected sections would be more effective. You'd be fine composting the infected pear leaves, ideally covering them rather than leaving exposed to the air so they can't continue to distribute airborne spores.
I don't think the rust should cause too much long term damage to the tree, but if you have any concerns about the stability of the tree you'd need to consult a tree surgeon.
The spores are produced when the knobbly pustules are produced underneath the orange spots. One reason for removing leaves which show rust spots is to prevent the spore producing organs from forming, lessening the amount of spores produced to go on and infect junipers. For that reason I would still recommend removing affected leaves as soon as you see them. However, if that means removing most of the leaves from the tree I agree it may do more harm than good. I have had some success in cutting the affected part of each leaf away with scissors on young trees so as much leaf area as possible is preserved. Of course, if the spot is near the base of the leaf then the whole leaf is removed.
In the case of large trees, all you can really do is sweep up and burn fallen leaves.
Thank you for all of the advice - I'll pass it on to my Nana. The little growths are all over the leaves and are so ugly; even my husband - who is usually braver than I am when it comes to bugs etc - was grossed out by them! But the tree is massive and there's no way they could all be picked off. In fact I forgot fruit trees could even get so big!
YOU THINK THAT'S UGLY. TAKE A LOOK AT ATHLETE'S FOOT.
If you live in Derbyshire, as I do.
Fungi is no fun, for plant, animal or human!
PANSY!!!
I WAS JUST GOING TO HAVE MY TEA