Hi-

Blackberry- the dieback of leaves on the blackberry stem may have been caused by a borer feeding inside the stem below the dying leaves. Swollen areas on stems are a sign of stem borers. It's also possible that the leaves died due to a lack of water and/or excessive heat. The plants are close to the white house siding. If this is south-facing the plants may be experiencing excessively high temperatures causing plant stress, resulting in drying and burning of leaf and stem tissue. In any case, prune out all dead and dying leaves and shoots.

Blueberry- the discoloration of some of the blueberry leaves is due to minor plant stress and the fact that we are at the end of the growing season when leaves naturally turn red-purple.

There are several diseases that can infect blueberry stems (e.g., Septoria, Botryosphaeria)

http://ncblueberryjournal.blogspot.com/2011/08/blueberry-stem-canker.html

It is possible that the stem lesions on your plant are caused by a disease although we would also expect to see wilting and dieback of affected stems and possibly leaf lesions. 

The safest thing to do would be to prune out the cane with the symptoms after the first hard frost. If the root system is healthy you will see new shoots emerge in spring. If you decide to leave the cane you can monitor it in the spring and if symptoms worsen you can prune it out then.

Blueberry plants need a 4 ft. x 4 ft. space to grow well (unless it's a dwarf or "container" variety). 

Here is more blueberry and blackberry information:

https://extension.umd.edu/programs/environment-natural-resources/program-areas/home-and-garden-information-center/food-gardening/fruits-home-garden

Jon