White Drupelets

Those tiny clusters of juicy goodness that form raspberries and blackberries are called drupelets. Sometimes you will see drupelets that are white or tan. Those pale drupelets may be the result of radiation.

Blackberries with white drupelets (S. Hermann and F. Ritcher) Pixabay

Radiation bleaching

Before you panic, we are not reviewing a 1950s horror movie. Instead, we are talking about ultraviolet (UV) radiation that occurs when temperatures suddenly rise and humidity drops.

Humid air diffuses and scatters UV rays. Hot, dry air allows more UV rays to reach your cane fruit. If the change is sudden, say, a good breeze comes along, the plants and berries don’t always have enough time to prepare, and some of the drupelets become bleached. Some varietals are more susceptible to white drupelet than others. Kiowa and Apache blackberries and Caroline red raspberries are the least likely to be affected.

Shading and overhead misting can stabilize temperatures and humidity in areas that frequently experience extreme temperatures. But the plants will still need time to dry out each afternoon to avoid fungal diseases.

Irrigation problems

The white or tan drupelets are perfectly safe to eat, but their presence may indicate an irrigation problem. If your raspberry or blackberry leaves exhibit signs of sunburn, you may need to provide plants with more water each day. Creating delicious fruit takes a lot of water.

Insect feeding

Feeding by stinkbugs and redberry mites can also cause white drupelets, but the damage will look different. Radiation damage will affect a generalized area, while pest damage will affect random berries and drupelets.
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Monitor raspberry and blackberry plants regularly to make it easier to determine the cause of white drupelets. Plus, it gives you the first pick of any ripe berries!