What Causes Misshapen Strawberries?

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In addition to lots of questions about spotted wing drosophila (SWD) in the last few weeks, I’ve also gotten several questions about misshapen strawberries. This post from NC Small Fruit & Specialty Crop IPM addressed this question last year.

As an update to last year’s post, however, lygus bugs (Lygus hesperus in the western US and L. lineolaris here) are not the cause of misshapen berries that I have seen so far this spring. I have not seen lygus active in fields yet this spring, and with our cool weather, I would not expect them to be present until toward the end of the strawberry season.

Poor pollination, however, is very common this spring. Cool weather and frost protection, particularly the long term use of row covers, limits bee activity and may impact flowers. Poor pollination can be distinguished from other damage by examing seed size in the constricted areas of fruit. If the seeds are smaller in these areas, then pollination is the most likely cause.

Misshapen strawberry due to poor pollination (top) and a normal strawberry. Note variability in seed size between the two fruit. Photo: HJB

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What causes misshapen strawberries?NC Small Fruit & Specialty Crop IPM