Pest Qa


Article by David Marks
Our main Pear tree pest and disease article can be found here. But sometimes our readers ask specific questions which are not covered in the main article. This page lists their comments, questions and answers. At the end of this page there is also a form for you to submit any new question or comment you have.


Date: 9 May 2021 From: Graham
QUESTION: I have a 4 yr old William Bob Chretien pear tree and notice a grey mildew on the blossom buds. Also, these buds fall off easily. It flowered profusely, but I now fear I may lose the fruit. Your thoughts would be appreciated.

ANSWER: If it has flowered there is nothing to be done except wait and see. April this year has been much colder than average and for a longer period than average, this may have damaged the buds. Couple that with one of the driest April months for many years – this may also have made to buds prone to some type of mildew.


Date: 10 July 2018 From: Derek
QUESTION: I’ve tried treating my pear trees with fungicide with little or no effect and wondered if you could tell me:
1. What disease(s) do they have
2. Can they be treated
3. What do I need to treat them
4. Is there a treatment plan you can suggestThe remaining fruits are currently healthy but will undoubtedly succumb to black spots as they grow. I suspect I have more than one problem and am relatively new to gardening so am desperate for help. If it makes any difference I’m in Aberdeen in the north east of Scotland. I don’t mind putting in the work if you’ve any suggestions and have attached some photos that will hopefully allow you to identify the problem(s).

Pear Leaf Blister Mite
Picture copyright notice

ANSWER: My strong suspicion is that this is Pear Leaf Blister Mite. I doubt it can be anything else.

I have a description about this pest and on that section in the website I show some affected leaves. The ones I show have deep red marks on them, but black, as in your case, is just as common.

The single picture of the damaged fruit you have supplied matches the diagnosis, especially if only a few fruits are affected.

The page I have about this disease can be found here.


Date: 5 November 2017 From: Lillie
QUESTION: Thank you ever so much for your website, the detailed information on pear rust has really helped me understand what is ailing my new pear plant (a bare root that i planted in my back yard about 6 months ago).

The pear plant is a mix of 4 varieties and it is meant to be self pollinating. It is planted next to a fence, where unfortunately it is next to a growing holly tree in a south facing garden and gets very little direct sunlight. It has also got badly infested with pear rust – i believe this may have travelled from my neighbour’s pear tree, that is just over the fence and has not been doing too well either.

There are very few spots in my garden that get more sunlight. Do you suggest i move the sapling now during the winter to a more sunny spot? My neighbour is worried that i might move it closer to the house and the roots of the tree may affect our houses.

Your advice would be hugely helpful – I want to save my pear plant.

ANSWER: A pear tree will never do well in shade, they can survive in shade but are unlikely to produce fruit and will also be open to pests and diseases. So, if you can move it to a sunnier spot and it is only six months old, do so. The correct time would be December to early March when the tree is fully dormant.

As to whether the roots will damage your houses, you need to consider how close to the houses it is planted and also what rootstock it is on. Possibly the tree still has its original label attached to it and that may give the rootstock. Let’s deal with the four most common possibilities.

This is extremely unlikely nowadays (especially with a 4 variety type). If it was grown on its own roots it could easily reach 7 metres high.

This is very possible and the tree would reach a height of about 3.5m.

Also very possible, the tree would reach a maximum height of 3m.

Possible but unlikely, the tree would reach a maximum height of 4.5m.

I would personally say that, with a pear tree, you need to plant it at a distance away from buildings of at least its height. Without knowing the rootstock that’s about as clear as I can get.


Date: 18 October 2017 From: Lillie
QUESTION: I’ve had my pear tree for years and never lost any blooms to frost. The last two years I’ve sprayed the blooms because leaves turn dark and fruit is obviously wormy. Doing this I’ve killed most of the blooms and what fruit has produced is still infected. How can I treat the tree without killing the blooms? Someone told me they’d never heard of treating a pear tree.

ANSWER: I think you may have two problems with your pear tree. The first, the loss of blossom and dark leaves, is in all probability Fireblight. See our page on identifying and treating fireblight here. Fireblight became increasingly common in the UK during 2016 and this has continued through  2017.

The second problem, worms in the remaining fruit, is probably pear midge, see our page all about pear midge here. Unfortunately Fireblight is very difficult to cure and you may need to remove the tree.


Date: 17 April 2017 From: Ray H
QUESTION: I have a 3 year old Conference Pear which gave a good crop of fruit last year, it has now been infested with Pear leaf Blister Mite, I have removed all the infected leaves. My first question is: will the fruit be affected? Second question, which winter tree wash do you recommend?.

ANSWER: Normally the fruits are not affected so you have a good chance of a good crop this year. I haven’t ever compared the various brands of winter was, personally I would choose Vitax Winter Wash.


Date: 15 March 2017 From: Beverley
QUESTION: I planted a young pear tree early last year and I tend to it regularly although I am still uncertain as to whether anything will become of it, early this morning I noticed bright orange blobs on the bark near the top of the tree, can this be treated or should I just remove it completely? I also read that the spores can travel to other trees and plants, do I need to be worried about my apple trees? Would love your advice about this matter as I am a new amateur gardener.

ANSWER: I believe it’s a fungal disease called Coral Spot. Normally it affects currant bushes and figs but it can affect almost any shrub or tree.

There is no chemical or non-chemical treatment. The only action is to watch out for it and cut away affected branches and twigs as soon as you notice it.

Yes it does spread, particularly to all the currant bush plants.


Date: 20 April 2016 From: Carolyn
QUESTION: Some of the developing fruit on my pear tree appears to have pear midges; but they also have minute orange spots covering a good portion of the fruit. What can I do about this, and what is it?

ANSWER: I would concentrate on treating the pear midges first. These pests will weaken your tree and its general health will suffer leaving it open to a variety of fungal infections. One of these is rust which can cause orange spots on the leaves and fruits.


Date: 6 October 2015 From: Mary Doherty
QUESTION: My Winter Nelis Pear tree 4-5 years old has good blossom, sets lots of fruit which blackens and falls while still very tiny why? This year it produced its first full sized fruit should we remove the tree or carry on?

ANSWER: The normal cause of pear fruit which blackens and falls off when small is pear midge (see above). I am a bit confused however because you mention that this year the tree has produced full-sized fruit for the first time so it appears that the situation is improving. So I don’t understand why you would want to remove the tree. My advice would be to treat it for pear midge as described in previous sections above and hope that nest year the situation is even better.


Date: 9 September 2015 From: Tony Taylerson
QUESTION: I have planted a new pear tree approx. 2 yrs old. It is now host to a number of small black leech like creatures approx. half a cm long, they are a shiny black in colour. Do have I reason to be concerned?

ANSWER: The short answer is probably yes! You sent in a couple of pictures as well which show that these black, leech like creatures are Pear Slug Sawfly. I have written a new section above with more information about these pests, the damage they do and treatment options. The section can be found here.



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