We believe that your blackberry likely suffers from White Drupelet Syndrome.

A drupelet is the individual ‘ball’ on the berry fruit that surrounds the seeds. Occasionally, you may find a berry that appears white in color, especially on its drupelets. This condition is known as White Drupelet Syndrome, or disorder.

There a few possible reasons why this happens. The most common reason for blackberries and raspberries with spots is sunscald. Unseasonably warm and windy weather can cause this issue. Most often, white drupelets will appear when there has been an abrupt increase in temperature accompanied by a drop in humidity; it is especially pronounced when there is wind. Berries that have full exposure to hot afternoon sun are more susceptible to this disorder as hot, dry air allows for more direct UV rays to penetrate the fruits. When sunscald is associated with White Drupelet Syndrome, the side of the fruit exposed to the sun will be white whereas the shaded side will remain normal.This year's hot, dry weather may have contributed to the problem.

Pests may also be responsible for the white spots in berries. Damage from stinkbugs or red mites can often lead to white drupelets. However, the discoloration caused from feeding damage will look quite different than that of sunscald or hot temperatures. The drupelets will have a more random patterning of white spots rather than a large general area.

To prevent white drupelets, avoid planting in sunny areas that are prone to hot summer winds. It may also help to orient your rows in a north-south facing position to minimize the effects of sunscald. Shading may be helpful as well; however, it is recommended only after pollination has already occurred. Shade cloth to protect the plants from afternoon sun can help.

Some advise to use overhead watering twice a day to cool plants during hot weather (for 15 minutes between morning and afternoon) to help alleviate sunscald. The limited watering cools the plants but evaporates quickly. This method is not recommended in evening hours as there must be adequate drying time in order to prevent the onset of disease later.

While a blackberry or raspberry with white drupelets may be unsightly, the fruit itself is still usable and relatively safe to eat, but may not be as tasty as ones not showing any damage. Of course, if the berries become hard and dry, they will not be palatable.

Thank you for contacting us regarding this issue. Please do not hesitate to contact us again should you have any other questions.