Darrow Blueberry plant- help?

Question: Hello,
My Darrow Blueberry plant was doing great up to one week ago, before the weekend heat wave.  Suddenly this morning, I looked at it and the leaves on one side of the plant, are wilted, brown color and appear to be dying.  the once flowering buds that were turning into small berries seem to be suddenly dried up.  i made sure to keep it watered during the heat wave.  the plant next to this one also has some browning leaves.  Help?  Is it due to just the heat?  Or, I hope there is not a fungus or disease traveling to the adjacent blueberry plants.  The first pictures, Darrow 1 and Darrow 2 are photos of the same plant - not looking good.  The additional photo, (Darrow - Healthy)  is the same type of plant but located several feet away from the plant not doing very well.  This plant seems to be just fine.    Please let me know if this was due to the heat, or if I should be more concerned?  

Thank you,

responder: Signe Danler, Online Home Horticulture Instructor Replied May 17, 2023, 4:27 PM EDT
response: This sudden hot weather has been hard on a lot of plants, and it is possible that is the cause of your blueberry's wilting. Is the damage on the parts of the shrub facing south or west, where it gets the brunt of the hot afternoon sun? I have to say, though, it looks more like an infection. Could you send sharp close-up photos of the berries that are involved, particularly looking for any fungal growths? Also examine the adjacent twigs and branches for any signs of discoloration or cankers, and send pics of those.

responder: The Question Asker Replied May 17, 2023, 7:10 PM EDT
response: Hello, Thank you for your quick response.  I just cannot believe this happened so suddenly to the plant that just a few weeks ago was very healthy. The damaged leaves are facing southwest.  (mostly to the south but we have direct sun coming into that part of our yard from the south and then west as the sun sets).  I tried shading the plant but I don’t think it was enough shade fast enough.  What is strange however, on a few parts of the same plant, (lower parts) there are still healthy looking blooms.   Photo no. 1 here, shows a few healthy blooms that are on the same plant.  Photo no. 2 shows the upper part of the plant with extreme wilted leaves and dried up looking  berries, ((or rather very small start of berries).   Photo no. 3 shows another wilted/dried up end of a branch with small berries almost looking burnt and falling off.  Photo no. 4 shows a leaf cluster just below, and I notice there are spots of light brown, kind of dust-like on the leaves.    This does look like fungus, but I’m not sure? Please advise if I should go ahead and cut off all the brown, dried up and/or spotted leaves asap?   (hopefully to try and save the adjacent blueberry plants) One last note,  just prior to this happening, when the plant was doing well and had a lot of blooms on it (prior to the heat wave)  I noticed several small ants climbing around the branches and blooms.  I’m not sure if the ants may have caused this?  I did not do anything to the plant when I saw the ants, as I thought the ants could not do any damage? Please advise,  Thank you, Anne Riggs Sent from Mail for Windows From: Ask ExtensionSent: Wednesday, May 17, 2023 1:27 PMTo: Anne RiggsSubject: Re: Darrow Blueberry plant- help? (#0100402)

responder: Signe Danler, Online Home Horticulture Instructor Replied May 18, 2023, 1:50 PM EDT
response: Darrow blueberry is particularly susceptible to Scorch https://pnwhandbooks.org/plantdisease/host-disease/blueberry-vaccinium-corymbosum-scorch and bacterial cankers. I see no sign of cankers on the stems you have pictured, so I think it is not that. It is entirely possible that, with the SW exposure, it is sun damage on tender new growth, and the black fungus on the berries is simply opportunistic growth on dead tissue. The ants are unlikely to have anything to do with it, though it was observant of you to notice them. Yes, you should remove all dead and damaged growth. Cut the stems at least a couple of inches below the damage, and pay attention to their cross-section in "healthy" growth - if there is discoloration it could be something like twig blight https://pnwhandbooks.org/plantdisease/host-disease/blueberry-vaccinium-corymbosum-twig-blight. Examine the pictures in these links and keep your eyes out for anything resembling them. If you cut tissue that appears like it might be diseased, sterilize the pruners before cutting into healthy tissue. If you don't see any signs of disease as you are pruning, it is probably heat/sun damage. That can happen literally in hours when plant are unprepared for it. It is typical for it to happen to the most exposed, upper parts of the plant, while lower (shaded) parts are spared. I am not sure what the brownish stuff on some of the leaves is, but it doesn't really look like a fungus. Does it brush or wash off? If may just be pollen or something that stuck to the leaves when they were damp.