I have a long established pear tree in my garden- it was here when I moved in 10 years ago.
It was badly neglected and overgrew a path, so I gave it a trim and a trellis to grow against. For a couple of years it bore some good fruit, but then went into decline. Every spring it would grow nicely, and be green, and then the leaves would get some kind of bug or mite and curl. The fruit, if any, would be scarred and not very appetising. I tried various things over the years, and ended up cutting the whole thing back to the trunk on a kind of “kill or cure” idea. This also enabled me to train it against the wall, solving the path problem.
Last year, I had no pest problem, but no flowers or fruit either. This year looked really good, with good growth, and lots of flowers. However, there are signs of the pest again.
Pictures follow after the cut.
I’ve looked in books and online, but have yet to find something that looks like this.
At the moment I am treating it by spraying with a mild soap solution, as I suspect it is some kind of insect or aphid, but any advice would be appreciated.
Turns out what my pear tree has is Pear Leaf Blister Mite:
http://www.gardenorganic.org.uk/todo_now/faqs.php?id=173
http://www.omafra.gov.on.ca/english/crops/hort/news/hortmatt/2007/14hrt07a8.htm
These mites overwinter in the tree’s bud scales, emerging with the new growth. This is why the leaves that develop on the old growth look fine at first. The new growth from the infected buds then allows the mites to spread to the rest of the healthy tree. Once source I found says this is particularly a problem with trees growing against a brick wall, which fits the bill in my case.
The treatment is simply to remove all and any shoots and leaves affected, before it can spread elsewhere. Thankfully, it does not involve serious damage to the tree itself, and a mature tree should recover from even the worst infection. It can cause nasty scarring of the fruit, but hopefully I can avoid that if I keep removing affected leaves.