3

We live in Vienna, Austria, very near the Danube river. We planted this apricot tree back in spring of 2015 as a small tree bought from a local nursery. It has been growing very quickly and was always very lush with leaves and flowers. Last summer (2017) it bore fruit for the first time, but the fruit did not ripen. This spring we decided to prune it a little bit to start shaping it to fit our needs in the garden. We pruned it in late March and by end of May we noticed the leaves shriveling and dying. Throughout the late spring and summer, the tree was bare, dropping dead leaves. Can you tell me what the disease is and what can be (if anything) done about it.

Thank you so much.

Photos: Whole tree Shriveled leaf Twig with shriveled leaves Branches with shriveled leaves Bark

  • Any problems anywhere on the main trunk, right down to the ground? Check it - you're looking for weeping, or soggy darkened areas, or soft areas, shedding bark, anything that shouldn't be there – Bamboo Aug 27 '18 at 20:13
  • Thanks for the question. I don't see any problems with the trunk, it looks fairly normal, no different than other years when the tree thrived. Definitely no soft or soggy areas. The older bark is rough to touch while the newer is still smooth. – Andraz Zuccato Aug 28 '18 at 7:33
  • I take it your area suffered the same six week drought and high temperatures as the rest of Europe this summer? That would a cause – kevinsky Aug 28 '18 at 17:11
2

You should probably prepare for bad news. The tree shows signs of bacterial canker infection which is reinforced by your description of the onset of the problem. The infection enters through cuts, blossoms and tools used to prune. It is made more likely in areas with a cold climate not tempered by the proximity of large bodies of water. It can affect cherries and peach and apricot and particularly the latter which is more affected by cold and is more susceptible.

Outward signs are raised rough black lesions on an otherwise smooth bark, blossoms that fall off prematurely, and sudden death of what yesterday appeared to be perfectly vibrant shoots. The first two may not be visible, but the last is. The infection is spreading inside the tree from the top down, killing the sap transportation tissues.

The tree may try to send up new shoots from low down on the trunk where the tissues are still good, and may even send up water shoots from a rootstock, but eventually the tree does not grow at all. It probably means that your location is too harsh for tender apricots.

By all means get other opinions, but consider removing the tree as soon as possible, your neighbours might consider it a source of infection and start mumbling, and wait years before trying a stone fruit tree again. I'm sorry, this is the worst, I know. Consider maybe an apple tree, which is hardier?

  • Thanks for the (bad) news. Holding on to some hope, I can't see any issues with black lesions on the bark. The tree flowered before the issue, so blossoms wouldn't help. The other thing is the environment. We chose the apricot tree because several of our neighbors have them and the their trees are performing wonderfully, and so did ours before pruning. We definitely have proof all around us that apricot trees fare well in this area. Does that change anything at all? – Andraz Zuccato Aug 28 '18 at 7:38
  • Well yes, I suppose, but I cannot think what, it would have to be something like deliberate root poisoning or tree planted on top of a barrel of oil, poison leaking onto the root area to kill the roots. By all means hold out hope, other suggestions will come... – Colin Beckingham Aug 28 '18 at 8:56
1

I haven't got good news either I'm afraid. The absence of soft, soggy, oozing or rotting areas rules out bacterial canker, but you might be looking at a case of Silver Leaf fungal infection or Phytoplasmas infection, which has been a problem in your area for some years. Silver leaf can be caused by pruning cuts made at the wrong time of year - stone fruit trees are best pruned around May to try to avoid this problem, but it can happen anyway. Symptoms would have included a silvering effect on the leaves prior to their rolling and going brown and dying, with eventual dieback of the shoots and branches https://www.rhs.org.uk/advice/profile?PID=245.

Phytoplasmas infection is commonly known as European Yellows, though it may by now have some other name, and it's been the cause of a major decline in apricot trees in Italy, France, the south east of the UK and in your area since the mid 2000's. This article https://onlinelibrary.wiley.com/doi/full/10.1046/j.1365-3059.2001.00536.x gives some detail - leaves often remain dangling on the tree, rolled, and papery looking, but most fall prematurely, and any fruits formed remain small and do not ripen. Over time it kills the tree; so far as I'm aware, no inoculum has been found to treat/prevent the disease.

It would seem there is no treatment for either of these fungal infections, so I'm afraid it's probably necessary to remove the tree - if you want to wait and see what it does next year, then you could try, but remove the dead shoots back to live wood.

Your Answer

By clicking "Post Your Answer", you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.