Rotating Cross Arm Trellis August update

Figure 1. Rotating cross arm trellis in August.

Earlier this spring, I posted a picture of a new trellis we are trialing at one of our research stations (http://teamrubus.blogspot.com/2012/05/rotating-cross-arm-trellis.html). Above is a picture taken on August 22, 2012.  We have 3 cultivars on each section of this trellis, Apache, Ouachita and Von (aka NC430).

Figure 2. Training of primocanes on wire. 

The second and third images show how we trained the primocanes to the bottom wire as they emerged from the crown. The canes were tied to the low horizontal wire. This encouraged buds that were on the horizontal wire to start growing. These secondary buds will produce canes that are very productive and are easier to train to the trellis because they are narrower. Fumi Takeda has done some very nice work describing the productivity of the buds in this paper. Here is a link to a summary of this work.
http://www.ars.usda.gov/research/publications/publications.htm?SEQ_NO_115=281491

Image 3. Close-up of training of primocanes on the horizontal wire. Photo: Fumi Takeda. 

To get the entire article, you will need to become a member of NARBA. (http://www.raspberryblackberry.org/subtopics.cfm?topic=Membership)

White (grey or tan) drupelets

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