Black raspberries very small

Hi all, I have a 2 year old Blackhawk black raspberry plant that’s yielding it’s first real crop this year. The berries coming through are plentiful but very tiny. See the photo below. Once the berries ripen to black, they’re not even the size of a blueberry. They have 6-10 little morsels (sorry for poor terminology).

Background is that I did no pruning of the primocanes in the winter and didn’t trellis them very well. This year I’ve learned a bit more and have some off season work to do. Is this normal with a young plant or due to my lack of pruning/cane management?

Conversely I have an Arapaho blackberry plant, same age, same lack of pruning that’s doing great and the unripe berries already look pretty large.

Thanks for any help or info.

Looks like bad pollination. Rainy weather can cause that. It’s rare in black raspberries, but that is what it looks like. Only a few drupes became pollinated. Virus infected plants could do that too.


I’d guess lack of pollination or the plant isn’t self fertile. Do you have other raspberries that bloom at the same time?

I agree that poor pollination could be the cause. Are there any normal berries or are they 100% affected? I’m no expert, but I would think that if poor pollination was the cause that at least some of the fruit would appear normal.

A quick internet search reveals many possible causes. Here’s a link to University of Kentucky paper on Poor Fruit Set in Brambles.

I suggest that you contact your local Extension Service. If others in your area have had a similar problem the Extension Service might be aware of it and have your answer quickly. In any case, they can assist in the diagnosis.

Let us know what you find.
Good Luck!

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Thanks for the fast responses. I don’t have any other raspberry plants, only the one other blackberry.

There are no “full sized” raspberries on the plant. Biggest was maybe the size of a regular blueberry. I have definitely seen some bees around, could it be that they prefer the blackberry nectar? The plants are only 5’ apart.

There should be no issue with eating these berries, correct? They taste great.

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Unless they’re moldy, go ahead and eat them. If it’s not a virus, then the plant probably isn’t completely self fertile.

I reached out to my local extension and got an unbelievably thorough answer with a variety of possible issues partly based on the yellowing leaves in the photo: over/under watering, poor draining soil, poor pruning/no trellis, no fertilizer. Either way, I’m going to keep the plant and try to follow best practices for next year. In the mean time, my young daughter likes picking the black ones and eating them fresh off the cane.