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Hi all,
One of my young pear trees has been (so far) non-fatally sick for the last couple of years and I'm struggling to diagnose the problem(s) accurately. I would like to think that all symptoms spring from one underlying problem, but I suspect it actually has multiple things wrong with it.
The other thing to bear in mind is that there is another pear nearby (about 5m away) which has also been in for a few years and so far shown no symptoms.
Here's a list of the symptoms. The first one is easy:
1. The red spots and growths under the leaves later in the season that I am 100% certain is Pear Rust. I don't think anything else common has the same colour and odd growths.
The next two I do not think can be symptoms of pear rust:
2. The first leaves of spring will grow as normal, but later leaves, including leaves on new growth, will tend to develop black bits on the edges and then curl. The leaves do not die back completely or fall off - they stay until the autumn, but distorted in shape. Since the first leaves of the season are generally OK, what you end up with is a healthier looking core of the tree with all the distorted leaves on the ends of the shoots and branches.
I haven't read about this being a possible symptom of pear rust, so I think it must be indicative of another pest or disease.
Pear leaf midge is a possible diagnosis for this, but I've never found any of the larvae, despite looking and flattening out some of the distorted leaves.
I don't think it's pear leaf blister mite as the development and placement (only on leaf edges) isn't consistent.
I don't think it's fireblight as blossom is unaffected and the shoots and branches don't die back. Also, symptoms don't occur on leaves from buds that showed symptoms in the previous year, since the symptoms always occur near the new growth.
2. Starting this year, several deep splits have developed in the bark directly below where some of the main branches emerge from the trunk. The splits are V-shaped and only underneath where some of the branches leave the trunk.
This is more worrying, obviously, than something attacking the leaves. To me, the shape and appearance of the splits doesn't look right for canker. It looks more like extremely uneven growth - like the branches have tried to grow too fast and split open the bark underneath them.
As discussed above, I'm doubtful that fireblight is the right diagnosis as the flowers look completely normal and then is no die-back further up the branches.
I am leaning towards tree stress being the likely explanation. The tree is in a very well drained spot in the garden, and this past year had quite prolonged dry spells in the summer. It seems possible that a combination of water stress (despite some watering on my part when I was in the country) and being attacked by a couple of different diseases is the cause of the bark splitting.
So my guess is:
1. leaf disorders
(i) pear rust
(ii) ??? - unknown other problem, could be pear leaf midge, but no larvae found despite checking both years
2. bark splitting due to tree stress caused by:
(i) very well drained site, not optimal for quince rootstock
(ii) other diseases / pests
The final question is whether it's worth just getting rid or not. I have a couple of extra trees coming this winter, an apple and a pear, so I could rip out this particular pear tree and put the new apple in its place (or in a new hole 1 - 2m away). Obviously an apple isn't an ideal replacement since it's part of the same family, but it's what I have.
I am not a huge fan of keeping trees that need constant chemical spraying to survive, so what are the chances of some non-chemical TLC (e.g. mulching around the base to increase moisture retention) helping enough for it to recover?
One of my young pear trees has been (so far) non-fatally sick for the last couple of years and I'm struggling to diagnose the problem(s) accurately. I would like to think that all symptoms spring from one underlying problem, but I suspect it actually has multiple things wrong with it.
The other thing to bear in mind is that there is another pear nearby (about 5m away) which has also been in for a few years and so far shown no symptoms.
Here's a list of the symptoms. The first one is easy:
1. The red spots and growths under the leaves later in the season that I am 100% certain is Pear Rust. I don't think anything else common has the same colour and odd growths.
The next two I do not think can be symptoms of pear rust:
2. The first leaves of spring will grow as normal, but later leaves, including leaves on new growth, will tend to develop black bits on the edges and then curl. The leaves do not die back completely or fall off - they stay until the autumn, but distorted in shape. Since the first leaves of the season are generally OK, what you end up with is a healthier looking core of the tree with all the distorted leaves on the ends of the shoots and branches.
I haven't read about this being a possible symptom of pear rust, so I think it must be indicative of another pest or disease.
Pear leaf midge is a possible diagnosis for this, but I've never found any of the larvae, despite looking and flattening out some of the distorted leaves.
I don't think it's pear leaf blister mite as the development and placement (only on leaf edges) isn't consistent.
I don't think it's fireblight as blossom is unaffected and the shoots and branches don't die back. Also, symptoms don't occur on leaves from buds that showed symptoms in the previous year, since the symptoms always occur near the new growth.
2. Starting this year, several deep splits have developed in the bark directly below where some of the main branches emerge from the trunk. The splits are V-shaped and only underneath where some of the branches leave the trunk.
This is more worrying, obviously, than something attacking the leaves. To me, the shape and appearance of the splits doesn't look right for canker. It looks more like extremely uneven growth - like the branches have tried to grow too fast and split open the bark underneath them.
As discussed above, I'm doubtful that fireblight is the right diagnosis as the flowers look completely normal and then is no die-back further up the branches.
I am leaning towards tree stress being the likely explanation. The tree is in a very well drained spot in the garden, and this past year had quite prolonged dry spells in the summer. It seems possible that a combination of water stress (despite some watering on my part when I was in the country) and being attacked by a couple of different diseases is the cause of the bark splitting.
So my guess is:
1. leaf disorders
(i) pear rust
(ii) ??? - unknown other problem, could be pear leaf midge, but no larvae found despite checking both years
2. bark splitting due to tree stress caused by:
(i) very well drained site, not optimal for quince rootstock
(ii) other diseases / pests
The final question is whether it's worth just getting rid or not. I have a couple of extra trees coming this winter, an apple and a pear, so I could rip out this particular pear tree and put the new apple in its place (or in a new hole 1 - 2m away). Obviously an apple isn't an ideal replacement since it's part of the same family, but it's what I have.
I am not a huge fan of keeping trees that need constant chemical spraying to survive, so what are the chances of some non-chemical TLC (e.g. mulching around the base to increase moisture retention) helping enough for it to recover?
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