Small red spots on Blueberry leaves

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Hey!

First post here. I’ve been growing blueberries for a few years in my garden. This winter I decided to start large scale hardwood/ semi hardwood propagation (after a couple winters of propagating here and there).

In one of my young bushes I purchased last year I’ve got small red spots on the leaves. I’ve done some research and can’t definitively say it’s one of the ringspot viruses. I’ve also got some purple color in a couple new growth leaves. What do you think?

For context, the soil on all of my bushes (young and old) is too alkaline. Definitely above the 5.5ph threshold. My other young bushes are showing signs of iron deficiency as a result of the PH. I’ve treated all the soils with pelleted sulfur, and re potted the young bushes adding spag peat moss and bagged ericaceous soil . Well aware that this will take months to correct, especially outside in the cold. I’ll be spraying chelated liquid iron in the short term. I’ve got urea and ammonium sulphate on stand by, I’ll probably be applying soon after more research.
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Meadowlark

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Welcome to the Forums.

What do you think?
Blueberries require a ph of 4.5 to 5.5 and closer to 4.5 than 5.5 in my experience. High soil pH levels (above 5.5) make it problematic for blueberries to absorb phosphorus.

Phosphorus deficiency can cause blueberry leaves to turn red. Increasing soil acidity and using phosphorus-rich fertilizers for blueberries are generally effective remedies.
 
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Thanks for the reply. Yep, the ph soil level seems to be the most critical element of growing blueberries. So many downstream deficiency problems as a result. The elemental sulfur I applied to all plants indoor and out should do the trick, just takes time. It’s definitely causing the purplish coloring in a couple leaves. And the yellowing in between green veins on my other young plants. Been watering with rain water since realizing the ph problem.

Any thoughts on the small red spots?
 

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To me, they are all part of the ph problem...but maybe @YumYum can spot some aphids?
 
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Gotcha.. definitely had an aphid problem a couple weeks ago. Noticed the honeydew excrement despite not really seeing the pests. Sprayed neem and got rid of them. Aphids will cause the small red spots? This may be it.
 

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I don't see iron chlorosis in that plant just yet but it probably isn't far off if the pH keeps rising. It kinda looks like you are washing whatever nutrients that are available to the plant right out of the container to me. A good fertilization and pH correction will likely straighten your problem out.

What do you fertilize with? Don't fertilize blueberries with any form of nitrate. Use ammonium or urea for the N. I use this stuff on my blueberries which also contains the micronutrients and is acidic.

Elemental sulfur has to be broken down by microbes, which require warm temps, into sulfuric acid before it actually lowers the soils pH level and can take some time. Iron sulfate is instant as is aluminum sulfate but I'm not fond of adding aluminum to my soil and not a big fan of adding too much iron either so I go the pelleted sulfur route myself.

You can also use a pH and TDS meter to check the medias runoff by using the pour through method. You could also add distilled white vinegar to your water to lower the pH to a suitable level and use the pH meter to test the final pH of the adjusted water. It would pay for itself in no time if you are buying alot of distilled water. I just use the cheap yellow and blue Vivosun meters but you have to calibrate it every time you get it out because it is always off a little each time for some reason.

Gotcha.. definitely had an aphid problem a couple weeks ago. Noticed the honeydew excrement despite not really seeing the pests. Sprayed neem and got rid of them. Aphids will cause the small red spots? This may be it.
Are you sure you are not seeing Edema instead of aphids honeydew? Aphids don't usually just walk off and leave. I'd say the red patches and spots are just another sign of a nutrient problem.
 

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