The tiny clusters of juicy goodness that make up raspberries and blackberries are called drupelets. Sometimes you will see drupelets that are white or tan. This is commonly caused by radiation.
Before you panic, we are not reviewing a 1950’s horror movie. Instead, we are talking about ultra-violet (UV) radiation that occurs when temperatures suddenly rise and humidity drops.
Humid air diffuses and scatters UV rays. Hot, dry air allows more of the UV rays to reach your caneberries. 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 are bleached.
Some varietals are more susceptible to white drupelet than others. Kiowa and Apache blackberry and Caroline red raspberry are the least likely to be affected.
In areas where temperature extremes are normal, shading and overhead misting can be used to stabilize temperatures and humidity. Plants will need time to dry out each afternoon to avoid fungal diseases.
The white or tan drupelets are perfectly safe to eat, but they may indicate an irrigation problem. If your raspberry or blackberry leaves are showing signs of sunburn, you may need to provide plants with more water each day.
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.
Monitoring raspberry and blackberry plants regularly can make it easier to determine the cause of white drupelets. (And it also gives you first choice on any ripe berries you happen to find!
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.