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BLACKBERRY BLOSSOM PROBLEM #874232

Asked June 22, 2024, 8:07 PM EDT

My Blackberry bushes have a nice amount of blossoms this year. Some of them aren't developing properly, the blossoms look normal but then,instead of fruit, I'm getting small light tan "things" that never develop into any fruit. I'm assuming that this a disease of some sort. It affects bunches of blossoms but leaves others to develop normally. I regularly spray with Immunox Fungicide but nothing else. Please let me know how to address thsi problem. Thank you, Harry

Cecil County Maryland

Expert Response

Hello Harry,

The symptoms are difficult to diagnose with certainty, but likely culprits include a disease called rosette (also called "double blossom"; not the same as rose rosette, even though blackberries are related to roses) and damage from a virus or phytoplasma infection. There may also be some overlapping insect feeding damage in the flowers/buds, as some frass (insect poop) looks visible, but this doesn't appear to be heavy enough to be responsible for all of the symptoms.

Unfortunately, wild blackberries, which are quite common in natural areas and which might be growing on a property nearby, are often associated with bramble viruses and phytoplasmas in cultivated settings. These wild plants can be a reservoir of diseases that are transmitted by insects (with sucking mouthparts, like leafhoppers and aphids) to cultivated brambles when the insects move from plant to plant. Once infected with a virus or phytoplasma, a plant can't be cured, though there are some management options with blackberry rosette.

Miri

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