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Restoring fruiting in blueberries

Posted by Heather Coiner 
Restoring fruiting in blueberries
June 11, 2014 04:48PM
Our blueberry patch has a very low fruit set this year, maybe 10% of what it should be. I think it is due to a lack of flowers, rather than pollen limitation, because our farm is abuzz with insects and many large (~5' tall) bushes had no flowers at all, while most had few. Last October we noticed that the patch was completely overgrown with weeds, and many of the bushes looked like they were panicking, sending up vigorous vertical unbranched shoots. In the winter we headed those back 30% or removed them at the base, and pruned out dead wood, though inspection now shows that we still missed some. We weeded to the drip line (avoiding tap-rooted dicots and clovers), fertilized with a low rate of microstart (composted chicken manure), azomite and boron (the fields were boron deficient though we didn't specifically test the blueberry soil this year), and then and laid a ring of hardwood chips under each bush. I also am including them in my spring and summer spray regimen.

Question: My intuition tells me that we are going into the time of year when next year's fruit buds will be forming, and I would like take action to restore fruiting. I suspect its at least partly a nutrition issue. Many leaves have intervenal yellowing, or even a red tinge, which I've read can be a sign of iron deficiency resulting from too-basic soils. What should I do? I would appreciate any recommendations the list has to offer.

Thank you!

Little Hat Creek Farm
Zone 7a, Roseland, VA



Edited 1 time(s). Last edit at 06/12/2014 03:03AM by Michael Phillips.
Re: Restoring fruiting in blueberries
June 16, 2014 08:59PM
Heather ,

I'm not experienced with blueberries myself but happened to bump into an aquaintance that is . His first question was what is your ph . Blueberries like to be more acidic , in the 4- 4.5 range . Simptom , low yeilds , sickly looking plants . A soil test would be good .

Also if memory serves me , these are fairly new to your care . Second question was how old is the wood ? They produce better on 2 -6 yr old wood , older wood doesn't produce well .

Just some thoughts

David
Re: Restoring fruiting in blueberries
June 19, 2014 12:48AM
Hi David,

Thank you for your reply. We don't know what the pH is--you can bet that we will be testing the soils later on in the summer. And your memory has served you well, we don't know how old the wood is. I'll be keeping the apparent age of the branches in mind when I'm pruning this winter, but I still think its strange that whole bushes have no fruit.

I had an insight however. Last year, we know that ducks were housed immediately uphill from the blueberries. By my reasoning, if their manure ran into the patch, you would expect vigorous, leafy bushes in the uphill portion and also no fruit, because I recall reading in Phillips that excess N in late summer and fall prevents fruit bud hardening. This is exactly the pattern that we see--the only bushes that are bearing are in the downhill portion. Does that sound plausible? If so, its an easy fix.

Best,
H.
Re: Restoring fruiting in blueberries
July 10, 2014 08:42PM
Hi Heather,

Yes, I would say Michael's excess N scenario sure could be part of your problem. Blueberries with excess nitrogen, late in the season, exhibit difficulty with hardening off and will usually produce less fruit too.

You are making good observations. Time to go deeper.

Take photos and notes of the leaves at different times of the season. It is amazing how much of the story the leaves, themselves, can tell. Measurements of shoot growth, notes on die back, and more, can all be useful in the final analysis too.

Soil pH is critical for Blueberries, more than almost any other fruiting crops we are likely to grow in our latitudes, as they are totally unable to pull key nutrients from the soil when their ideal pH range is not in place - no matter how fertile the ground is. This can surely create noticeable/visible trouble. Unfortunately, by the time you see it (yellowing leaves, veining, necrosis, etc.), it is fairly far along in the process and often from trauma and stress from the year before.

In addition to your soil evaluations, you may want to do some Leaf Tissue Analysis too. Talk to your local Ag Extension for a lab recommendation, if you don't have one in mind already.

There are numerous university publications to help with some of the fine tuning of Blueberry nutrition and production.

One real nice effort, I like, was put out by Michigan State University and it is called "Managing the Nutrition of Highbush Blueberries" You can get the PDF downloaded (~14Mb's) for free or you can buy a copy of the guide from them too.

If the hyperlink I added there doesn't work, google the phrase Managing the Nutrition of Highbush Blueberries and you will get a direct hit

Good luck to you and your blueberries!

Gopher Hill Apples
Zone 8 in California
Re: Restoring fruiting in blueberries
September 14, 2021 11:25PM
Paul, do you know of any recommendations for cottonseed meal as an amendment for pH? I see Michael's rec's for the amount per fall as maintenance, but no specific table for "I have X pH and need to get it to Y pH, so the rate should be such and such." I think the MSU publication you mentioned has such a table for Sulfur, but not cottonseed meal. I am attracted to the latter if it is a wee bit more organic and perhaps works faster in the soil.

Thanks!

-Josh

Earthworks
Zone 7a in West-Central MD
Re: Restoring fruiting in blueberries
October 23, 2021 08:14PM
Hi Paul,
Here is the link where I found "Managing the Nutrition of HJighbush Blueberries".

[www.canr.msu.edu]

Thanks for pointing out the publication!

John

Honey Meadow Farm, LLC
Southwestern New Hampshire, Zone 5A
Elevation: 960'
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