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Blueberry rotting on one side #200658

Asked July 19, 2014, 7:35 PM EDT

This year, I have a bumper crop of blueberries. However, some berries seem to have a problem that I haven't seen before. They get soft and discolored on about half of the berry. I've had these same bushes (Berkeley) since 2006 and haven't seen this problem before. Also, some of the leaves on the bushes seem to have what appears to be rust. I would appreciate it very much if you could help me identify the problem. Thanks.

Yamhill County Oregon

Expert Response

Sorry to hear about the loss of some of your blueberries.  But we may have an easy answer.  Has your area had any hail in recent weeks?  If so, that’s the likely causal agent. When hail hits green blueberries, the fruit is dented and often develops a dry brown spot somewhat later.  But if the fruit is ripe or ripening, the bruising by the hail begins the spoilage process.

You didn’t include an image of the rust-colored areas on the leaves.  I suspect that may be due to insufficient water or possibly even hail damage.  To resolve the issue, please send an image when you reply.


If you've not had hail, please send 3 more images: the bush overall; a midway shot of a branch against a plain background; and a close-up of an affected berry cluster.

Although this publication doesn’t discuss hail damage, it may be helpful: “Growing Blueberries in Your Home Garden” http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/12202/ec1304.pdf





Jean,

We have not had any hail storms that I'm aware of this spring. I live between Newberg and Dundee, Ore in Yamhill County. The photo of the berry that I previously sent shows the problem but I did not explain it very well. I am sorry. Anyway, one half of the berry is like a normal blueberry. I did not taste it. The affected side is almost like a rotten tomato. It is very soft in texture, very squishy, not firm at all, and quite discolored and feels rotted. I could not get a photo of a cluster of berries (most clusters are picked) but in general, only one berry out of a cluster might be affected and probably only one cluster out of five. I did not want it to get really bad if I can stop it. At first I thought sunburn because the berry damage is always on one side and is almost always half good, half bad. It is not usually on the top side. The previous photo I sent shows one side is affected and it is not the upper portion. Since you mentioned bruising this year we seem to have many more than normal Robins and various birds that have been jumping at the berries as well as flapping their wings while inside the bush branches to knock down some of the fruit. I have five bushes total and all seem to be affected, some more than others. However, the rust appearance on the leaves seems to be affecting the bushes that are a smaller and lighter in color. I also examined the leaves closely (magnified) to make sure there were no insect infestations or other problems I failed to find. As for watering, it is on an irrigated, dripper system. Each bush has two 2gal/hr drippers at the base. They get watered four days out of the week, twenty minutes each watering. So if I did my math correctly that is about 1.33 gals 4 days a week for a total of 5.33 gals a week. Each bush gets the same water but some bushes have more rust than others. We have watered the bushes the same way for about six years. I am thankful for the information about growing blueberries (ec1304.pdf). I had already downloaded the document when I first noticed the issue with my berries, hoping I could find the solution in there. Thus, I need the help of an expert. The documents posted on the website are very helpful for many different issues.



The Question Asker Replied July 20, 2014, 9:39 PM EDT

Thank you for your response with the images and the additional history. It’s obvious you’ve put a lot of thought into this problem.  So far, it doesn’t appear to fit any of the theories we’ve generated. (To be truthful, I doubt I would have considered stompin’ robins!)

Another possibility is spotted wing drosophila (SWD), a close relative and near twin of the nuisance fruit fly that hangs around bowls of ripe fruit.  SWD, an invasive pest which arrived in Oregon in 2009, attacks ripening soft fruit while they are still on the plant. Blueberries are among the common victims.  

Although you didn’t report seeing any small “worms” in the softened berries, I suggest we explore that possibility.  Please collect a dozen or so of such fruits to try to rear adult SWD flies.  Directions are in “Spotted Wing Drosophila (SWD)”  (http://www.metromastergardeners.org/files/nattersnotes/2013-8-Natter.pdf) The process may require 2 or 3 weeks.  (I’d appreciate it if you would notify me of the result.)

This article also includes several informative references for home garden fruit growers. The first two links will be especially useful if you discover SWD are active at your place:

- Recognize Fruit Damage from Spotted Wing Drosophila (SWD) http://spottedwing.org/system/files/em9021.pdf

- Protecting Garden Fruits from Spotted Wing Drosophila: http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/20883/em9026.pdf

The reddish coloration on the leaves is not due to the fungus disease rust. It may be an indication of brief water stress and excess solar radiation during our recent heat wave.





Thank you for looking over my data.  I have to admit the Stomping Robins are a stretch but it is such a strange problem with the berries that I was not about to exclude anything that may be a clue and, bruised berries from bird wings is a stretch but then, who knows?  I will see if I can incubate some of the flies.  I have not noticed any insects but it can not be ruled out yet.  I was raised in Colorado around the fruit orchards and farms and believe me, fruit flies are a very familiar part of the environment.  I am not sure I can get more affected berries because the crop is almost done but I will try.  I will keep you informed one way or the other.  I will get the documents you have suggested and try to grow us a flying bug.  Since I could only attach three photos to my last response, I am attaching another photo of a blueberry that more clearly shows how the berry is damaged on one side, not the top or bottom.  Weird.  Also, thank you for examining the leaf and bush photos.  I was suspicious that the heat may have caused the leaf damage because it seemed to begin during the unexpected hot spell and most of the damage occurred to the smaller bushes.

 

The Question Asker Replied July 22, 2014, 5:45 PM EDT

This image is more clear.  It makes me wonder if perhaps some of the fruits were ”cooked” by the heat on the exposed side. (Yes, I agree; that does sound strange.) 

I doubt SWD are the problem because the berry doesn’t look right for that.. (By the way, you wouldn’t have seen SWD years ago; they’re entirely new to the US since 2008.)

While you’re attempting to rear out flies, I’ll consult with a colleague who may have further suggestions.






My colleague suggested a common disease of blueberry fruit I hadn’t yet considered, namely this:

“It may be Mummy Berry. It seems to be very prevalent this year. I have noticed that many of my berries have it and some of them are not showing symptoms until they are blue then they get a grayish then pinkish sunken area on them. These berry pictures are not showing the area sunken, but if it starts to sink and turn pinkish then I would say it is definitely mummy berry. If the client tears the berry apart it will have a pinkish area inside near the off colored area.”

If the softening is due to mummy berry, the disease may start when Infected flowers turn brown and wither. (A second infection cycle begins later on infecting berries here and there.) The twig and associated stem may also be affected. By the end of the season, affected fruits turn pink, shrivel and drop. As noted above, symptoms seem to be delayed this year.

Cultural management is critical because no pesticides are available for use in home gardens.

Sanitation is key; collect and discard *all* mummies to help minimize infection the following year.

Resources for you:

- Mummy Berry (An Oregon State University person highly recommends this publication. Has a susceptibility chart that may be useful to you. Understand that, here in Oregon, the suggested chemicals are for professional use, only.) http://blogs.oregonstate.edu/mummyberry/files/2014/05/MUMMY-BERRY-FACT-SHEET.pdf

- This video describes how the disease develops and how to look for the mummies in the spring. http://www.youtube.com/watch?v=SyG-B0cr9gc&feature=youtu.be






Jean, I really appreciate the help and effort you are putting in on my issue.  When I first saw an affected berry, I was surprised to see how the berry was damaged.  Because it was so different from any other damaged fruit I had ever seen, it caught my attention.  Since I am a retired engineer, I just cannot pass up a problem that does not seen to have a logical answer.  Sometimes I do not find an answer but at least I try to find a solution.  But since I initially had only a couple affected berries, I was not overly concerned.  But as more of the berries displayed the same characteristics, I became more concerned, even to the point of questioning whether I should prepare to replace my bushes. I looked at a Blueberry Cultivar Susceptibility chart and it showed that in the case of Mummy Berry, the Berkeley blueberries were moderately resistant to Primary Infection but were susceptible to Secondary Infection.  I do not know what the primary or secondary methods of infection mean, a general lack of education.

At first, as you mentioned, I thought it might be a sun burn but because some of the affected berries were located central to the bush, I would not expect them to get burned by direct sunlight.

Then I decided to look on your website and downloaded the documents you suggested.  I found the Mummy Berry to be interesting, especially because of its name.  I began to pay close attention to the bushes, fruit, and especially the ground under the bushes.  I did not find any sign of Mummy Berry and during each picking, I watched for signs of the disease and found none.  Would the birds quickly eat the affected berries laying on the ground?  Could the birds carry some type of fungus or parasite to affect the berries in this manner?

As a general garden rule, I remove any unfit vegetables from my plants as well as ensuring that there are no rotting vegetables or fruit on the ground.  As a precaution, every time I picked berries, I removed any berry that looked unfit from the bush, usually damaged from bird beaks, and made sure there were no berries laying on the ground.  Looking at the picture in the Mummy Berry document, the cluster appears to have many affected berries, small berries.  For the most part, the berry clusters on my bushes are almost all nice with few to no small fruit.  Now, at the end of the season, I have more small but nice looking berries from the final picking.

I have not noticed any berries that appeared to have a grayish or pinkish area on them or sunken areas.  If I removed any of the skin, the underlying tissue just seems to be over ripe and squishy.  If a berry is infected, would all of it eventually turn a pinkish color or is it common to have only half of it turn soft and pink?  Also, you mentioned a twig could be affected.  Is there a way to identify that and if so, should I prune it from the bush?

Again, thank you very much for your help.  I have two berries in a jar and maybe I can grow a bug.  One berry is soft but I think it was bird damaged.  The second berry is a little on the green side but I found that it has what looks like a small worm hole.  ll see.
The Question Asker Replied July 23, 2014, 4:11 PM EDT

The difference between primary and secondary infections is their timing.  Primary infections occur during early spring, when the shrub is first flowering.  Entire flower clusters and often their associated stems are diseased. 

Secondary infections occur later in the season.  This time, individual berries - perhaps just several in a cluster - are affected.  If your bushes are infected with mummy berry, it would be a secondary infection.

Birds aren’t involved in the infection process.  The infectious fungal spores of the primary infections are air-borne whereas the spores of secondary infections are transferred by bees.  (See the illustration on page 3 of the document from Michigan State.)

Continue your practice of removing and discarding damaged fruit as it can be a useful tool in helping limit disease if it is present.  Also continue trying to rear out SWD.

I’ve gone as far as I can in trying to help you resolve this problem, so I will reassign your question to a Small Fruit specialist at the university. You may need to be patient as it may be a few days or more before you hear anything.

Good luck with your search for an answer.




Hello everyone,

The damage to this blueberry fruit is most definitely heat or sun burn damage. This has been very common this season as weather has been hotter than blueberries "like". The sun causes the fruit to soften on one side. This can happen on green fruit as well as blue fruit, depending on the conditions and the variety. It does look like a rot, but the pink softening is very typical of sun damage. There is no control other than misting the bushes overhead or making sure the ground is wet underneath the bushes -- the increased humidity decreases the incidence of sun burning. Some cultivars are more sensitive than others; with that said, many of the common home garden varieties have this problem this year. The good news is that once the weather cools, as it has this week, the problem "goes away" on fruit that is still ripening.
Thank you all very much for all the help and time spent resolving my little blueberry problem.  You provide a valuable service to those of us that feel a need to keep our vegetation healthy.  I think you all deserve to have a substantial salary increase this year, at least as much as the professional athletes get.  Thank you again.
The Question Asker Replied July 25, 2014, 4:50 PM EDT
Why thank you! Glad we could be of assistance

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