Poor pollination
Poorly pollinated berries tend to be small with a rough, dimpled, seedy appearance similar to that of boron deficiency.
More information:
- Chapter 7 Small Fruits and Brambles: Strawberry Pollination (pages 679-688 in: USDA Insect Pollination of Cultivated Crop Plants)
Use these resources if you need additional help with diagnosis and to find solutions to your problem.