Galls, duds, lesions, and drops—can these plants be saved?

Thanks again, Kathryn Wadsworth and David Deardorff, authors of What's Wrong With My Plant, for undertaking to diagnose 10 plant problems sent in by Rant readers. Here's the second set. 

The Plant Doctors Report, II

4. Christopher has 10,000 daffodils all blooming profusely in his annual “bulbapaloozathon” except for this one double flowered variety. Great photos show a daffodil with aborted flowers.

The daffodil in question didn’t really fail to flower. It actually produced flower stalks with flower buds (as shown in the photos). The flowers, however, aborted and turned brown inside the sheath before opening. No insects (thrips, for example) occur inside the buds. And to round out the mystery, 9,999 other daffodils bloom profusely under exactly the same cultural and environmental conditions in the same location.

Specific cultivars of double daffodils react to unseasonal cold snaps of freezing temperatures during bud formation by aborting the flowers. Daffodils in general are extremely hardy to cold temperatures, but a few are not. Many factors cause daffodil flowers to fail to form (overcrowding, undersized bulbs, removing foliage too soon, temperatures exceeding 80 degrees F) but this doesn’t apply here because there are a heck of a lot of daffodils all blooming their heads off, and only one that does not. Most likely, it is an issue with the particular cultivar in question, a double, and probably it was just too cold for that variety at a critical moment in its development.

Note to Christopher from Elizabeth: I have the same problem (doubles and planted in a clump just like yours), but I have found that the daffs can and will blossom after being duds the previous season. It is totally arbitrary. You say in comments that you are going to dig them up, but I think you should keep that in mind.

5. Harold Malaby sent wonderful photos of oak tree branches with large, round galls on them.

Insect larvae of gall wasps cause these galls to form. Mom lays her eggs under the bark of the tree. When the egg hatches, the baby wasp (a maggot-like grub) starts to feed on the tree and the grub’s saliva contains chemicals that cause the tree to build a house (the gall) around him. When he matures he chews a hole in the gall and flies away.

These galls do not threaten the life or health of your tree. You can simply prune them off if they’re unsightly. If you do your pruning while the babies are still inside their galls and destroy them before they mature you disrupt the life cycle and gain a measure of control over the problem. Examine the galls closely and, if there are no exit holes, the wasp larva is still inside. But, of course, many more gall wasps exist in the neighborhood and surrounding forest lands. So, complete control is not an option.

6. Kathy Purdy sent us photos of her Juneberry (Amelanchier x grandiflora ‘Autumn Brilliance’) because every summer it drops seventy five percent of its leaves. The original set of photos weren’t up close enough to see the leaves in detail, so we asked for more photos. Kathy posted six more photos with good close ups of the leaves and we’ve looked at all of them.

We looked carefully for tell-tale signs of leaf-spot fungi. But none of the spots demonstrated those signs. In addition, this hybrid juneberry (Amelanchier laevis and A. intermedia) is resistant to the leaf spot fungus disease (Coccomyces tumidus) that causes juneberry leaves to fall off in summer.

The spots appear to be the angular patches left by the pear slug, a sawfly larva which rasps away the soft green tissue from the surface of the leaves. Although this is a common problem on juneberries, it does not cause the leaves to fall off.

We observed that several leaves in the photos turned yellow from the tip, a characteristic symptom of insufficient water.

Kathy’s email said that the leaf drop problem occurs in wet and dry years, regardless of how well hydrated the soil is. Thus, we conclude that insufficient water is not due to simple drought. In this case, some other factor impacts the plant’s ability to bring water from the roots to the leaves. Possibilities include: 1. Too much fertilizer or other salts in the soil. 2.  Damage to the root system by insects, rodents, root rot or other pathogenic fungi. 3. Construction/digging in the root zone. 4. A combination of wind, bright sun, and high temperature at the same time.

The bottom line -- we don’t have enough information to build a case history and come to an accurate diagnosis. But Kathy certainly does, and she should be able to examine those factors and solve the problem. By the way, this little tree is gorgeous in full bloom. A real knock-out. (See all the pictures and more on this problem on Kathy's blog, here.)

7. Kathleen Sherin sent photos of a young ‘Reliance’ peach tree with ugly lesions on the trunk and branches that look like they’re oozing gum. She says it’s a young tree, less than one year in the ground.

The lesions on this peach tree, blackish cankers oozing gum, typify bacterial infections in stonefruit trees. ‘Reliance’ is supposed to be resistant to bacterial spot (caused by Xanthomonas pruni) so we have to suspect it is the other common bacterial disease of stonefruits, bacterial canker (caused by Pseudomonas syringae).

These bacterial infections are common on cherries, peaches, plums and other stonefruits. Very difficult to cure, they can eventually kill your tree. To treat it, prune away all the infected tissue (and then sterilize your tools!). Then, spray the tree with a copper-based remedy. Copper is effective against both fungi and bacteria and is a good organic choice for your tree. But in spite of your best efforts you will probably lose this tree sooner or later. And, as stated in your notes, the lesions are everywhere and if you prune them all away there will be nothing left.

Our best recommendation: remove this sick tree and get a healthy one. Look for a tree that’s fully leafed out and growing in a pot. Examine it carefully for signs of cankers or oozing gum. Choose a healthy one to take home. Do not plant it in the same hole where the sick one was. Treat the new tree with a copper-based remedy to prevent future bacterial infections.

Tomorrow: the final set of problems and the announcement of book winners!

Comments

[Michele Owens]

Wow, I was going to send a photo of my peach tree with similar lesions on its trunk.

The tree fruits so beautifully, however, that I think I'll leave it in place until it kicks the bucket.

[Christopher C NC]

Thanks Docs. That is good news for the Bulbapaloozathon and bad news for this daffodil cultivar. It can't be reasonably said that we have "unseasonal cold snaps of freezing temperatures during bud formation", at any point of bud formation.

This daffodil is doomed to dudness. It's only hope is to be dug up and shipped south.

[Kathy from Cold Climate Gardening]

Thank you for taking the time to "look" at my Juneberry. Too much fertilizer, no. Don't use it. Rodents, yes. Voles and chipmunks R Us. Digging in the root zone? Occasionally, but not much, to plant or divide a perennial. I guess I'd have to vote for bright sun, wind, etc. as it also happens to at least one native, wild-growing Juneberry up in our field, the one in full sun that I pass on my way up to the woods.

And I second Elizabeth in saying that daffodils whose buds blast in one year will bloom fine the next year. It may not be cold but drought at a certain point in development that does it, because we certainly get cold enough every year, and yet some years they bloom fine. But because we have a shallow well, I don't water the ornamental garden in a dry year.

[Benjamin]

Is that serviceberry a victim of cedar apple rust?

[Kaviani]

Re: Failed double blooms- I had the exact same problem with a peony-ish hibiscus. 80% of buds failed to blossom and the rest were heavy and unwieldy to the point of looking ridiculous. Everything drooped and the limbs grew deformed. That's what I get for going for glamour.

Re: Peach tree- damn, that just makes me sad, but removal really is best. Throw the carcass in the garbage to ensure it won't infect any cousins. I'd even treat the soil with copper and neem, then solarize it for a LONG time to ensure anything in its spot is dead.

[David Deardorff]

Thank you all for your comments. We really enjoy the opportunity to "cyber-chat" with plant lovers.

Chris's Daffies: Don't blame you for shipping it south! There are other double daffodils that are resistant to bud blast. However,it is certainly possible that this one will bloom well for you next year -- depends on the weather.

Michele, if your peach tree blooms and sets fruits even though it has bacterial lesions, we can understand your desire to keep it. And that may be just fine, but do be aware it is a source of inoculum to infect other stonefruit trees.

Kathy's juneberry (aka serviceberry): You might want to check the roots and make sure they are intact and healthy, since you do have rodents (voles) that may be snacking on the roots. The problem is not cedar apple rust because no fungal lesions appeared on the leaves.

[Christopher C NC]

David my memory is next to non-existent .... but I do seem to recall this same clump doing the same thing last year and it was flagged for division as a possible problem, then forgotten. This year while paying more attention I saw many of the same variety in other spots with the same problem. It must have been divided before.

There are not many tulips here for a reason. Fussiness is not allowed in the wild cultivated garden. I will recommend to Bulbarella that she toss the whole lot. There is no sense is spreading a dud around.

[Rhonda]

I've identified my fungus issue...black knot on 4 Canada Red Cherry trees, severe, from a distance I had thought I was looking at pods on a catalpa tree. The growths look like a nest of snakes up close.
And the owners (neighbors)don't return from snowbirding until after the foliage covers it, and in addition, suffer from "Horticulturus tight-walletus"
Meanwhile my innocent little North Star cherry is vulnerable to this windborn fungus.

[Karen B.]

I have a young peach tree with what looks to be the same problem, though it currently just has one lesion. Thank you, Kathleen, for sending in your photo, and many thanks to the expert authors for the diagnosis and treatment.