Sick Blueberry bushes - Ask Extension
Hello. I purchased 6 three year old blueberry bushes from a NJ grower in the spring. I made my first mistake when I planted them while they were fruit...
Knowledgebase
Sick Blueberry bushes #847446
Asked August 26, 2023, 9:23 PM EDT
Hello. I purchased 6 three year old blueberry bushes from a NJ grower in the spring. I made my first mistake when I planted them while they were fruiting, in raised beds (I dug a "ditch" 12 inches deep below the bottom of the raised bed) then added a mix of Canadian peat moss, sand and soil for acid loving plants. Since then, I've added "Fast Acting Sulfur with Nutri-Bond Run Off Reduction Technology", sprayed them with chelated Iron and Neem oil, made sure they were getting appropriate water, and the pH is still 6.5. How do I get the pH down and what else can I do to help them survive? I've attached photos of two of the worst looking trees and one that seems to be ok, but is starting to get the same yellow/red leaves.
Any advice is appreciated.
Kindly,
Terry Marvel
New Castle County Delaware
Expert Response
Hi Terry,
Thanks for reaching out to Ask Extension. As a blueberry grower myself i may be able to make a few suggestions.
The pictures you have provided are very helpful and show the discoloration perfectly. Blueberry leaves can discolor for a multitude of reasons but the two top reasons would be a lack or excess of water and/or soil that is not acidic enough.
You have indicated that the pH of your soil is 6.5. Did you have the soil tested by a lab or are you using a home test kit/device? My first recommendation would be to have the soil tested by a lab and fortunately we have a lab right here at the University of Delaware:
https://www.udel.edu/canr/cooperative-extension/environmental-stewardship/soil-testing/
The red leaves are a clear indication that the issue is most likely pH so let's begin there. You have mentioned the type of soil and amendments that you have used so I would wait on the results of a soil test before you add anything else. While you need the pH to be lowered you don't want to go too low; that could be just as detrimental to the plants as a high pH.
One of the amendments that you mentioned is sulfur - sulfur is great but the results from that addition can take up to several months to change the pH of the soil. It seems as though you are familiar with the pH requirement of blueberry bushes (4.0-5.5 being the optimum pH) so the goal here is to get the soil to that level.
Things that can affect soil pH are water, the material used to make the raised beds and/or other additives that you may have used such as fertilizer or compost. The ideal situation would be to have the soil at the required pH first and then plant the bushes but I know how we gardeners are - we want everything NOW!!
Get the soil checked and if need be try to lower the pH, but only after the results are in. You have already tried a few things to lower the pH and here are some more examples:
Organic mulch – this will help lower the pH if you are using acidic mulches such as pine needles or oak leaves.
Compost tea – as long as you have used organic material that is acidic you will be ok using a compost tea to help acidify the soil
Leaf mold is a great additive for the soil but again it depends on the leaves used. This would be something you could work on for the future but it will take time to have the leaves decompose and to get the required level of decomposition.
An acid fertilizer is a good idea as well – one that is specifically made for acid loving plants such as azaleas and rhododendrons.
Be careful about adding coffee grounds to the soil – the only coffee grounds you should add are straight coffee grounds nothing with an additive for flavor.
Bottom line – get the soil tested first. Once you know what you are dealing with you will know what direction to go. The UD soil test results will also give you recommendations for what needs to be added to your soil based on the pH.
Good Luck and let us know if you need further information or assistance.
Again – thanks for reaching out to Ask Extension!
J.W. Wistermayer
UD NCC Master Gardener
Thanks for reaching out to Ask Extension. As a blueberry grower myself i may be able to make a few suggestions.
The pictures you have provided are very helpful and show the discoloration perfectly. Blueberry leaves can discolor for a multitude of reasons but the two top reasons would be a lack or excess of water and/or soil that is not acidic enough.
You have indicated that the pH of your soil is 6.5. Did you have the soil tested by a lab or are you using a home test kit/device? My first recommendation would be to have the soil tested by a lab and fortunately we have a lab right here at the University of Delaware:
https://www.udel.edu/canr/cooperative-extension/environmental-stewardship/soil-testing/
The red leaves are a clear indication that the issue is most likely pH so let's begin there. You have mentioned the type of soil and amendments that you have used so I would wait on the results of a soil test before you add anything else. While you need the pH to be lowered you don't want to go too low; that could be just as detrimental to the plants as a high pH.
One of the amendments that you mentioned is sulfur - sulfur is great but the results from that addition can take up to several months to change the pH of the soil. It seems as though you are familiar with the pH requirement of blueberry bushes (4.0-5.5 being the optimum pH) so the goal here is to get the soil to that level.
Things that can affect soil pH are water, the material used to make the raised beds and/or other additives that you may have used such as fertilizer or compost. The ideal situation would be to have the soil at the required pH first and then plant the bushes but I know how we gardeners are - we want everything NOW!!
Get the soil checked and if need be try to lower the pH, but only after the results are in. You have already tried a few things to lower the pH and here are some more examples:
Organic mulch – this will help lower the pH if you are using acidic mulches such as pine needles or oak leaves.
Compost tea – as long as you have used organic material that is acidic you will be ok using a compost tea to help acidify the soil
Leaf mold is a great additive for the soil but again it depends on the leaves used. This would be something you could work on for the future but it will take time to have the leaves decompose and to get the required level of decomposition.
An acid fertilizer is a good idea as well – one that is specifically made for acid loving plants such as azaleas and rhododendrons.
Be careful about adding coffee grounds to the soil – the only coffee grounds you should add are straight coffee grounds nothing with an additive for flavor.
Bottom line – get the soil tested first. Once you know what you are dealing with you will know what direction to go. The UD soil test results will also give you recommendations for what needs to be added to your soil based on the pH.
Good Luck and let us know if you need further information or assistance.
Again – thanks for reaching out to Ask Extension!
J.W. Wistermayer
UD NCC Master Gardener
