Orchard Pest & Disease Watch, 2020 Edition

Inspecting trees for fruit-load and thinning out excess fruitlets – which, as I mentioned in my last post is an essential orchard task at this time of year – also provides an opportunity to check for incipient and ongoing pest & disease problems.

As you might be able to see from the final bucket-load of thinnings and trimmings from last Sunday’s session, there are a few p&d issues in the Plot #79 orchard at the moment:

There’s evidence there of side-stem die-back (the medlar has been under-watered, so I need to keep an eye on its irrigation over the summer), possible powdery mildew on an apple, and some worrying brown blotches on the leaves of one pear-tree (it wasn’t too far from the quince, which suffered an attack of what I think was fire-blight last year – see below – so again I’ll need to monitor it). Also, although you might not be able to make them out, I did snip off a fair few curled-over leaves that were infested with aphids (see my post from last year on spotting an aphid infestation).

The plum ‘Burbank’s Tangerine’ tree had also suffered some pretty severe wind-damage on a recent gusty day:

The branch was still hanging off the tree by its bark when I found it (actually, when a plot-neighbour kindly pointed it out to me), and had caused quite a vicious-looking wound:

I’ve trimmed back from the above and cleaned the wound up as best I can, but that’s definitely one to keep an eye on. Water could gather in the hollow at the base of the wound and cause the branch to rot, or the weight of the remaining branch could snap through the remaining woody tissue, so it may well need further pruning or cutting back, which would be a real shame as the tree hasn’t yet set fruit, and we’ve lost so many potential fruiting buds already. And looking again, there appears to be a hollow in the wood just above the wound itself – that could be an indicator of some sort of disease or other damage, so I’ll need to re-check that next time I’m down at the plot.

There are also signs of apple canker on one of the cooking apple trees in the form of tell-tale sunken, reddish-brown patches in the bark of one of its stems, which I removed as soon as I spotted it:

This was trimmed from ‘Lord Clyde’, a heritage cultivar that I’d be loathe to lose. But if apple canker has taken hold and continues to spread then the tree might need to be cut down and replaced, if only to stop the disease spreading to its neighbours. I’ll be monitoring this one very closely indeed.

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