For those of you who know me by my real name on Facebook, you may have seen this in a group or two, but I’m trying to get some information.
I have a blackberry patch consisting of several varieties. The ones in question here are Arapaho, Natchez, and I think Caddo (supposed to be Galaxy but I’m 99% sure these were mislabeled, but I’ll post another thread about that).
After a five day trip, I came back and noticed that a lot of the primocane tips were dying. I see no evidence of lesions, canker, or the telltale rings from cane borers. The pith is white with no streaks or evidence of borer that I can see.
Furthermore, where the tips have died back, it looks like lateral buds are pushing, and the canes are still trying to grow. It almost looks like heat or drought stress, but I’ve kept them well watered, and it’s been at least 10 days since we’ve had any really hot weather.
I’ve never seen this (atleast to this extent) on my own plants, but what about spur blight? I suggest cutting down atleast one affected cane and going through it with a fine tooth comb to see if there’s anything you’re missing. Cutting into the cane to look for discoloration from the normal light green/white might also provide some more info. The fact that it seems to be affecting multiple canes on the same plant seems like something systemic though.
I know that the post I am referencing is for raspberries but I wonder if it might not still apply given how densely planted your blackberries appear to be.
But I also wonder if it could be a virus that spread from the raspberries.
Even if it’s rare in blackberries, I still think it’s something like spur blight:
Spur Blight
Spur blight is caused by the fungus Didymella applanata. It affects red, black, and purple raspberries. Blackberries appear to be highly resistant. Spots appear on new canes in mid-to late summer.
Symptoms. Spots on leaves of first-year canes begin at the edges and grow inwards, following the veins. The spot is V-shaped, and brown with yellow edges. The entire leaf is usually pale. Leaves usually fall off. The fungus grows through the leaf, and into the cane.
Chestnut brown-to purple spots are formed on the canes, usually around a leaf joint. The spots may grow together, although they usually stop before the next leaf joint is reached. On the second-year canes, the spots fade to gray, and tiny black dots appear in them. Infected canes are weakened. Fewer fruiting spurs are formed and those are usually weakened. If the disease remains confined to the lower portions of the plant, little yield loss occurs.
Oh you’d be surprised, especially if it creeps up over time if they’re on a rigid drip schedule not necessarily controlled by an accurate soil moisture reading. The only way to know for sure is to dig one up and the candidate would likely be your worst one. It sucks because if there isn’t root rot then you just caused a bunch of stress, but if there is, it’s probably good to know now.
Well how did you determine the emitter rate to use for drip? How do you know you’re giving them the correct amount of moisture? The reason I mentioned spur blight is because it’s something I’ve been dealing with on one of my plants, although typically it leaves the petioles unharmed and merely the leaves drop off (amongst other things). If we think about it logically in your case, you’re getting straight up wilting of the entire petiole and set of leaves - similar to what you’d see with a plant going through heat stress but it’s permanent. You do get new growth afterwards in response, which is definitely an interesting data point but you have something systemic going on that’s affecting multiple plants and it’s either irrigation or a virus. Could still be a fungal disease of some sort but they don’t usually act this aggressive and I don’t think it’s pests.
I’ve had the same thing happen to some potted prime ark freedoms if I fail to water adequately in the peak of summer. The plants have recovered just fine with adequate hydration. I’m having to water the potted blackberries daily now with the extreme heat we’ve been having.
The soil has been moist but not wet when I’ve dug down a bit. It’s fairly sandy and drains well, but none of my other plants (on the same irrigation zone) have shown any stress, even finicky stuff like corn, which is often the first to wilt in a drought in my experience.
It’s possible it was some “perfect storm” of water stress at just the right (wrong) time. Doesn’t fit the symptoms of Phytophthora, and it doesn’t look like what I see online for spur blight either. Nothing quite “fits”.
Interesting, but neither of these really fit. Some of the leaves have scorch at the tips, which doesn’t fit the progression of either of these, plus, the floricanes look fine for the most part. One pic shows one a bit died back but that’s literally the only one. Otherwise it’s just the tips of the primocanes.
