In the last few days I have had several calls and emails from growers concerned about white drupelets. Here are a few points that I have gleaned from experience and other articles (see links at the end of the post).
- It is thought that this condition is caused by UV radiation and appears when there has been an sudden increase in temperatures.
- Rainfall appears to make the problem worse, with sunlight on wet berries plus high temperatures. (We have had quite a bit rain in parts of NC lately).
- This was thought to be a result of stinkbug damage many years ago. BUT not now.
- Apache shows more of this problem than any other variety, but white drupelets have been seen on most of the Arkansas varieties.
- Tolerance for white drupelet varies to some extent by grower. Growers that ship berries have no tolerance, while pick-your-own growers can tolerate a few white drupelets (see last point, educate your clientele).
- White drupelet disorder is usually a problem early in the season and then disappears.
- The berries are still edible, they make delicious pies, juice, ice cream...
For more information see
http://plantpathology.uark.edu/Number_15-2010.pdf
and
http://www.raspberryblackberry.com/Webdocs/nabga08-06news.pdf
