Sad Cherries

Asked March 9, 2018, 4:40 PM EST

Every year my cherry trees start out with ton's of flowers and beautiful looking little cherry buds. But soon they begin to shrivel and all fall off. No one has been able to give any ideas as to why. If you have any suggestions as to what I might do to narrow down the possibilities that would be very much appreciated. I just don't know how to proceed. We have bees on site. The varieties are Rainier, Sweet Heart, Van, and Combo (BN, LP, RN, MN). I think I have the right cross pollinators per the chart I found. I used copper once over the winter and and one application of ECHO (Chlorothalonil). My plan was to use Sulfur (waiting the for a month after the copper) as my primary fungicide but also an application of Eagle 20EW (myclobutanil: a-butyl-a-(chlorophenyl)-1H-1,2,4,triazole-1-propanenitrile) for Brown Rot. I try to use as little fungicide as I can but being located in the Willamette Valley it's tough given the wet springs. I know I should probably stop trying to grow cherries but I'm figuring since there were once flourishing maraschino cherry farms around here someone might know how to make cherries grow successfully. The trees have some canker but they look very healthy. Lots of foliage. No die back anywhere.

Multnomah County Oregon

20 Responses

Thanks for your question. The cherries in the right photo appear to have something like brown rot on their ends, but would need to be viewed under a microscope to determine if that fungus is present. You said you have bees on your property. Have you cut open a cherry to confirm that it has a pit (so you're certain it was fertilized)? Do you give your trees supplemental watering or do they need to depend on nature? I wonder if you could post some photos of the leaves, and of the trees from a distance? There might be information from those sources that would help with a diagnosis. In the meantime, you might find some assistance in this Extension article.

I'm looking forward to more info!

Kristena, thank you so much for getting back to me. Let me first answer your questions. Yes, the cherries last year had pits, however I'll be especially careful to check for that again this year. The trees are watered. In addition they are downhill from a septic field so I think they are getting plenty of water. I've posted photos of the orchard facing west and east. The hill slopes down to the west. Note there is some shading due to the large firs south of the orchard. I've got just over 20 trees of which 4 are cherries. I didn't take pictures of the leaves last year but they looked pretty healthy other than a few having holes in them. I'll take pictures as soon as they are out this year. I'm familiar with the article you linked to and have not only read that one but almost anything else I have been able to get my hands on. The initial guess was brown rot but everyone seems confused about how all the cherries suddenly begin to shrivel and drop at once.

My hope is to get some advice as to what to do this season to narrow down the possible list of problems. So for example if you can tell me what to look for under the microscope (I have one) or who I might be able to send a few samples of the cherries and leaves to that would be immensely helpful. Also perhaps a suggestion for what to spray that might help eliminate possible causes. I posted what I've used in the past but I fear that I might not have sprayed as frequently as required for example. I've used a number of fungicides but eagle is the only one that is listed as being particularly effective against brown rot I believe. I also forgot to mention that last year I alternated with Ziram 76DF. Finally if it would help I have pictures of each individual tree.

Okay, so you've given me lots more information to research. Here are 'red flags:'

How far from the drainage field are the trees? Some soil borne bacteria doesn't leach out adequately, and may be taken up by a plant's roots. And some trees appear to be more susceptible than others.

If you look at a fruit under a microscope, a fungal infection would exhibit some structure 'furry.' This article has some good information on that, as well as photos of the fungal masses.

I'm afraid I can't supply any more information about spraying other than that in the EC 631 publication.

The holes in the leaves are typically indicative of insects, but distinguishing one from another (and knowing when it first begins) through photos is essential.

The other potential culprit are the Drosophila suzukii (spotted wing fruit fly) or the Rhagoletis indifferens Curran (Western cherry fruit fly). I'll give you a link to the former, and a link to the latter, but monitoring is the beginning of the control. It does also require cutting open the cherry to see if there is internal damage to the fruit.

So, let's keep exploring whether it is abiotic (surrounding circumstances), pathogenic (something's trying to kill them) or caused by insect infestations before you spray any more than you feel comfortable with. Nature is complex.

Thanks for getting back so quickly. I just measured and the last line in the septic field is about 50' uphill from the cherry trees, however I notice in the summer that the grass is only green above the first line which makes me think that little to no water is making it to lines two and three. This wouldn't be surprising because its a large field. If that's true then the trees are more like 80-100' away.

I guess my question is what should I do, or prepared to do, in order the narrow the possible list of causes? For example, should I run a soil test (possible lack of trace elements)? Once the trees flower and then after petal fall should I be ready to take sample and photograph them or send them to a lab for analysis?

Such a puzzle with so many variables! It will not hurt to have a soil test. A & L Western Labs can test for many issues. Without seeing the insides of the fruit (for insect damage), my intuition is a lack of water, especially in light of our prior years’ droughts. Get back to me with soil test results, okay?

A&L can't fault for pathogens. Would you like to see a fault for that or just the complete analysis that A&L does?

Thanks again for the help. STeve

Sorry. Darn spell checker...

Would you like to see a test for that or just the complete analysis that A&L does?

Whatever A & L tests for is helpful. The OSU plant clinic also tests for some limited pathogens. I’d suggest starting with soil.

Lots more information! But I'm not sure they're related, except that a stressed tree can develop a myriad of problems. When were the photos taken of the leaf with holes in it? Early spring, summer or fall? It helps to know what the weather was when they first occurred.

Here are some things to read while you're waiting for soil test results:

Why cherries don't ripen
Bacterial canker on cherry trees

We'll keep working on it!

The pictures of the leaves were taken at the same time as the cherries, so springtime.

I'm wondering if it might be a Boron deficiency.

Boron isn't typically a problem for cherry trees, and we have lots in our clay soil.

I just noticed two tiny 'things' on the right side of the leaf with holes. I cannot tell whether it is plant tissue, or insects. We have cherry slugs here, that morph into sawflies. Slugs cause this type of damage. But the larvae are usually green.

I have much more detailed pictures that I just examined and don't see anything. If you would like me to email the photos at full resolution I'd be happy to send them. You can reach me at edelmanATmail(dot)com. That's mail notgmail.

I've never seen any slugs on the trees.

Thanks again for your help.

They're not really slugs; they're just called that. They are larvae that have tiny legs, and chew!

Here's the soil analysis. Does anything stand out as troublesome?

Yes. Soil pH. Really low (acidic). These trees can live in 5.5 to 6.0 range but prefer more neutral (closer to 6.5) range. I’ll provide more info tomorrow.

I searched some more, and found this Extension article which indicates that the necessary pH range is between 6.0 and 7.0. Your soil is 5.6, which is why A & L recommended liming, and gave you recommended amounts to apply. (As you previously noted, a boron deficiency implicates fruiting problems, but is best measured through leaf, as opposed to fruit, analysis.) Here is an article which explains the interaction between soil pH and nutrient uptake.

Rather than risk over-supplementation of boron, I think I'd just use their liming information, and hope that a less acidic soil will produce better cherries this year. And, continuous monitoring for cherry slugs and sawflies (holes in leaves from the former), should help nip this in the bud, so to speak, although not much you can do about them. Hope this gets you further along this season. Fingers crossed!

I added lime, gypsum and a smidgen of boron. I've also been keeping up with the spraying just to make sure that isn't the issue. Thanks for the articles. I'll post how it goes.

Great! I’m looking forward to it!