Blueberry bush wilting

Asked July 23, 2020, 6:43 PM EDT

I have four blueberry bushes. All of them are currently suffering from sunburn (browning of the leaves), but one of them may be suffering from something else as well. The tips of several canes are wilting and dying. This has always been my healthiest and best producing bush, so I'm very concerned. The berries on all my bushes this year are shriveled, and I assume this is because of the heat, although this hasn't happened to this degree in the past, so I'm attaching a picture of the berries as well, just in case it's relevant.

Josephine County Oregon

6 Responses

The symptoms you describe, leaf burn, wilting, and wrinkled fruit, sound like drought stress.
The OSU publication Growing Blueberries in Your Home Garden
describes how much water blueberries need: (Mature) plants need from 1.5 to 3 inches of water a week. Irrigate to supplement rainfall as needed. Irrigate frequently enough to prevent the soil from becoming too dry.
Considering how hot it has been lately, and our lack of rainfall, you may need more than 3 inches, but avoid overwatering. Check the soil frequently. It also recommends maintaining 6 inches of mulch around the bushes, which will help keep the soil moist.
This Michigan State Extension article has pictures and descriptions that can confirm that your bushes are suffering from drought.

Thank you very much! I was afraid it might be mummy berry, since we've had weather this hot in previous summers but the cane tips never withered before and the berries never shriveled this badly. I'm relieved to know it's just drought. I do have about six inches of pine needle mulch on each bush, but I don't know how to measure how many inches of water they get.

I have a drip line on each bush with 7 one-gallon drippers. Up until recently, I've been running it a half hour (3.5 gallons) every other day, which works out to 12.25 gallons per week per bush. When the weather gets up in the mid-90s or higher, I increase it to 45 minutes (5.25 gallons) every other day, which is 18.38 gallons a week. Just this past week, I've increased it to 1 hour (7 gallons) every other day, which is 24.5 gallons per week per bush.

I have no idea how this translates to inches per week, though.Can you help me out? 24 gallons a week per bush sounds like a lot and I don't want to overwater them but, apparently, I haven't been giving them enough.

Thank you for your help!

To find out how long it takes to put an inch of water on your blueberry bushes take a shallow, at least one inch deep container and put it under a dripper. Measure how long it takes to put an inch of water in it. That can guide you in putting 3 inches of water on your bushes in one week. If it takes an hour to fill one inch, then you know to run it over the course of a week for 3 hours.
Also you need to check your drippers frequently as they can become plugged and put out little to no water. Checking if the soil is damp can tell you if the dripper is working.
Bubblers can be useful for large shrubs, such as blueberry bushes, as described in this publication Drip Irrigation for Home Gardens

Putting a container under the dripper won't tell you how many inches of water the bush is getting. The number of inches that accumulate in a container is determined by the diameter of the container. Given the same amount of water, a container with a 3' diameter will accumulate two inches of water at the same time a container with a 6" diameter will accumulate one inch of water when water is poured into each at the same rate.

I was originally using bubbler, but the bushes were developing fungal problems because the lower leaves and stems got wet whenever I watered, so I switched to drippers. But, with seven drippers and the line coiled twice around each bush, I get pretty good coverage because of capillary action in the soil. The only question is how long to run the drippers.

Using a tuna fish can to measure how much water overhead sprinklers are putting on different areas of your lawn and garden is a common method. Apparently you don't think that would work on dripper output, You do know that the water the blueberry bushes are getting is inadequate. So all I can suggest is increasing the watering time with the system you have now in the hopes of stopping the symptoms of drought.

Thanks for using Ask an Expert.

I've used tuna fish cans before myself. If the water is falling in an even pattern everywhere, like with rain or an overhead sprinkler, it's different than with a dripper, where the water isn't spread out over an even area, but is being collected directly from the source.If you sprinkled seven gallons of water evenly over a patch of ground over the period of an hour, a single tuna fish can would not catch one seventh of the total amount of water being sprinkeled. But if you have seven one gallon drippers, and put a tuna fish can under one of them, it would collect exactly one seventh of all the water being distributed. That's why the can system doesn't work the same way with drippers as with an overhead sprinkler.

I have increased it to one hour every other day, so maybe that will be enough. If I check the ground under the mulch the night before the drip runs, how wet or how dry should it be?

Thank you very much for your time!