Something causing rabbiteye blueberry leaves to shrivel


#1

There’s something causing my rabbit eye blueberry leaves to shrivel. I’ve sprayed a few doses of neem oil but it appears to not be working. On inspection, I never see an insect at work, and they are currently netted, so it can’t be a rabbit or bird.
I should add that the 5 rabbiteyes that I’ve planted have been in the ground for 4 years with low vigor, this is the first year we’ve gotten enough berries to make it worth netting, but they are only around 20" high, with 1 almost dying off completely last year. Could it be a canker of some kind? Any ideas for treatment?


#2

That looks more like physiological problems than a disease. The soil and/or nutrients may be the problem. Micronutrient deficiency of nickel and/or zinc are one possible issue. Also, the weak yearly growth suggests lack of major nutrients N-P-K. Have you checked the PH of the soil?


#3

Hey there @Fusion_power, thanks for weighing in! I need to check with our extension office to do a soil test soon. I’d read that rabbiteyes are less picky about the ph, and they get lots of kelp, homemade fish emulsion, etc. but it’s quite possible that it’s something specific. I appreciate your suggestion!


#4

GM Fusion, Just a thought. Is there any possibility of herbicide damage? Glysophate drift could be a factor if sprayed close by and was blown over by the wind. Randy/GA


#5

Glyphosate damage shows up as yellowish streaks and spots in the leaves giving them a variegated look. From the pictures, I don’t think roundup is an issue, but will let Kdegs say if it is possible. You don’t have to spray plants direct with glyphosate to get leaf damage. Spraying within 10 feet of some plants is enough to trigger leaf color and growth changes.


#6

My friend grows them, and watered them with DI water for several years I think. He might have used vinegar too. They grow well now.


#7

They’ve been in the ground for 4 years and are only 20" tall sounds alarming to me. I would guess that something wasn’t done correctly when they were planted and they’ve suffered because of it. At 4 years old they should be much larger. A quote from the NC Extension:

“In the fourth year, the bush should be 4-5 ft tall and capable of handling a crop…”

I live in the same area as you and have some rabbiteyes that were planted in Feb 2019 which are now probably 4-5 feet tall. They were planted pretty close to the recommendations found in the above link.

Some of the recommendations are:

  • Test pH - if above 5.3 add sulfur - mine was 5.8 - added sulfur

  • Plant in full to at least 50% sun - mine are somewhere in between

  • Incorporate organic material (peat moss, pine bark, etc) into the planting area - The fall prior to planting I removed turf in a 3 ft wide row, then mounded peat moss, compost and shredded leaves at least a foot high in the middle

  • Mound the planting area to improve drainage - done

  • Mulch with 3-4 inches of material to retain moisture - added a few inches of wood chips after planting

I suggest that you read the above link and think about how your planting compares to the recommendations. I suspect the pH is fine, but that they were planted directly into heavy clay soil without modification.

Perhaps you have done everything correctly, if so, please let us know. There are some really knowledgeable blueberry growers here that may shed some more light on what’s going on.

Contacting the NCState Extension would be worthwhile.


#8

@randy_ga, Glyphosate drift would be really noticeable in our yard, we have plants everywhere. I doubt that it would be that, but good to know about!
@Monardella, What’s DI water? Love your username btw
@BerryGuy, it’s always nice to hear from a local :slight_smile:
I didn’t do a soil test when I moved here, but went from other people’s advice that rabbiteyes are “easier” than other blueberries. The soil is more loamy than clay, and I planted the patch adjacent to a patch of pines and azaleas, assuming that the acidity would be good from years of pine needles, etc. Sun is never a problem with us, if anything they get too dry. I’ve just sent off a soil test, so I’m excited to hear more!
An ongoing problem in our yard is bamboo that creeps into our garden from the wild sides of our yard. Even doing the soil sample just now, I found a few bamboo roots- we’ve started calling them bamboo brains, because they are so fibrous and seemingly smart about where to go for nutrients. The stuff is everywhere! We might build raised beds for the bushes to protect them from the bamboo.
Thanks to everyone for their insights!


#9

The bamboo may be a part of the problem and a raised bed would certainly help, though the bamboo may eventually get in there. I’d put bamboo eradication on my to-do-list.

Your loamy soil will drain fairly fast, so mulch is very important. It’s hard to tell from your pictures how well the plants are mulched, but it looks like there is bare soil in the lower right corner of the third picture. If so, I’d put at least a couple of inches of mulch over the entire area. Pine needles look nice, but I don’t think they are as effective as other mulches at retaining soil moisture.

I’m sure you’ll work it out and have more blueberries than you can eat in the seasons to come. Good luck and please keep us updated.


#10

DI = deionized water.


#11

@BerryGuy, we are working on clearing the bamboo, but the roots still run everywhere. It’s been there longer than we have, but hopefully we can starve it out in the years to come. I think we will do a raised bed, and use landscaping cloth which I otherwise wouldn’t use. That might help protect them and they won’t need a super deep bed with their shallow roots.
I’ll report back if the soil test yields anything. Thanks for the insight!


#12

@BerryGuy
I got the soil test back and the ph is a whopping 6.9! The soil content is otherwise pretty good, better than my apple patch surprisingly. Guess we’ll have to do some major reworking this fall. Please let me know if here are amendments that have worked well for you.


#13

You can water with citric acid or vinegar in the meantime. They will lower pH just as quickly as Sulfuric acid depending on concentration. Use a ph meter to make sure your water isn’t too low in ph.


#14

Blueberries need around 5-6 pH and don’t like city water which is 8pH. To lower pH I use phosphoric acid from the hardware store. It is also a plant nutrient. They also need acid azalea fertilizer.


#15

Mulch with pine needles instead of peat moss. They lower PH over time. Use some form of acid to water the soil which will rapidly reduce PH. Incorporate some sulfur into the soil, but be careful, PH can drop too fast causing problems with growth.

6.9 is really not that high, but for blueberries, it is very much a problem. Most tales of slow growing blueberry plants wind up being related to soil PH.


#16

I agree with most of the above suggestions. However, I have read that pine needles don’t lower soil pH.

From Oregon State Extension:
" MYTH: Ponderosa pine needles make the soil more acidic (low pH).

REALITY: The notion that pine needle change the soil pH so that nothing will grow or that it will damage plants has been out there for years. The truth is pine needles do not make the soil more acidic. It is true that pine needles have a pH of 3.2 to 3.8 (neutral is 7.0) when they drop from a tree. If you were to take the freshly fallen needles (before the needles decompose) and turn them into the soil right away, you may see a slight drop in the soil pH, but the change would not be damaging to the plants."

From New Hampshire Extension:
" Pine needles themselves are acidic but do not have the capacity to appreciably lower the soil pH. To do that, it is necessary to incorporate a soil acidifier such as sulfur or aluminum sulfate. If you are unsure of the pH in your garden, you should have the soil tested. As pine needles break down and are incorporated into the soil, decomposing organisms gradually neutralize them. Thus, there is no harm in using pine needles to mulch shrub borders, flower beds and vegetable gardens. Even a 2 to 3 inch layer of pine mulch will not change the soil pH enough to measure."

I’m surprised that your soil pH is so high. Most soils in our area have a pH in the 5 range. Make sure you haven’t added anything to your soil that may have increased the pH. Do you know the history of the location the blueberries are planted? Maybe the soil was amended with lime in the past and the pH is still high.

With high pH soil blueberry leaves will appear light green with dark green veins. This is called iron chlorosis and is due to the plant’s inability to take up iron at the higher pH. The leaves on your plants look fine.

Also, rabbiteye blueberries are more tolerant of high pH, so I think you can still have success. I have read of others having good luck with rabbiteyes in neutral soil pH like yours.

If you had your soil tested by the NC Dept. of Ag. and let them know that you are growing blueberries, your report should have a suggestion on how to raise the soil pH. Here’s what my soil test report from 2018 said:

“It is difficult to lower soil pH to existing
blueberry plants; use of elemental sulfur (90% S) and ammonium fertilizer sources can be of benefit. Use proper safety handling instructions for use of elemental S; avoid breathing dust
and eye contact. Wash any S or fertilizer off plants to avoid burn. A rate of 5 lb per 1,000 sq ft of S will typically lower pH by 1 unit (6.0 to 5.0) for sandy soils; double the rate for clay soils.” I followed this advice, but haven’t retested the soil pH. I plan to this fall.

My suggestion is to play it safe and lower the soil pH. Apply sulfur at the rate suggested above or as in your report if different. Do this as soon as possible because it will take many months for the drop in pH. I would test your soil again in the spring to see where it’s at then. Soil tests are free in NC between April and November.

I would measure the pH of your water and adjust it down, if needed, as suggest by others. Be careful when using strong acids!

Rainwater has a pH in the 5 range, so you might consider setting up a rain-barrel to collect water for your blueberry plants if your supply water pH is high. I had success with this when I lived in Illinois.

Use ammonium fertilizer as suggest in the soil test report and by others above.

I wouldn’t let the plants produce fruit next year. Let them put energy into growth. I have experimented with this in the past and have confirmed that the plants will grow much faster if not allowed to fruit when small. My experience has been that the plants put growth on hold when developing fruit and then return to growing again after harvest.

It has been several weeks since you first posted this topic. How are the plants doing now?


#17

@BerryGuy, thanks for checking in! I planted them near an area with pines and azaleas thinking the soil would be plenty acidic there. It was one of the first beds in the yard, and upon digging, I was surprised the soil was rockier than other parts of my yard, with much less clay.
This week, I got the soil test results back and had tested most of the garden plots in the yard. It looked like the areas with clay tended to be more acidic. It seems like my hunch about the pines and azaleas being more acidic soil wasn’t correct in this case.
I’ve been watering with vinegar water, per @Fusion_power 's advice on here. I will add the sulfur soon, but wanted to wait until the temperatures go down a bit. So far, there has not been much of a change.
Next year, I will take your advice about not letting them bear fruit. Is it best to just trim the flowers or wait until fruit set?


#18

The problem was mulching with peat moss which tends to raise PH over time. Pine needles don’t raise PH.


#19

Sorry for not responding earlier with my prior post. I was off the grid in the mountains for a few days to escape the hot weather. :grinning:

Since you have lower pH locations on your property it might be easier to just move the plants this winter and avoid the whole adjusting the pH problem.

If that’s not an option for you, add the sulfur as soon as possible for two reasons. First is that the sulfur is converted into sulfuric acid by soil bacteria. This process takes many months and will slow or stop during the winter, so you need to get it started soon. Second is that your plants are already in the ground which means that you can’t work the sulfur into the soil without disturbing the roots. You’ll need to spread it over the planting area and let it slowly work its way into the soil with watering and rain.

As far as not allowing fruit next year, just pull off the flowers as they form. Fast and easy.


#20

Some good advice but I wanted to comment on vinegar. Acetic acid an organic acid easily breaks down by bacteria in two weeks. So pH returns to where it was quickly. In a container the hydrogen in the acid can combine with carbonates and be washed out of the soil but not with in ground plantings. So it can work in containers. Not so much in ground.