Cane blight at end of season?

Cane blight infection at tip of cane where it had been pruned as a primocane.

Cane bight symptoms in entire canes.  Dead canes are silvery/gray in appearance. Photo phil Brannen. UGA

As the blackberry season winds down, there are several reports of loss of crop and cane death before the crop ripens. This is often occurring in plantings that are low or no spray such as homeowners and small commercial plantings. The canes become infected when they are primocanes as tipping or pruning occurs in the summer. 

In at least one instance, samples sent into the NCSU Plant Insect and Disease Clinic have confirmed that Cane Blight caused by the fungus, Leptosphaeria coniothyrium. This disease is common in roses and some ornamentals. 

Here is a link to the disease. http://extension.uga.edu/publications/detail.cfm?number=C894

Here is a link to the IPM manual that has control methods: http://www.smallfruits.org/SmallFruitsRegGuide/Guides/2016/2016BrambleSprayGuide.pdf

and and article on the disease http://www.smallfruits.org/bramble/pestinformation/caneblightfactsheetii.pdf

Please send in samples to your states disease clinic to confirm any diagnosis.

Phil Brannen, UGA also sent these comments on fields with infected canes:

"On the current canes, there is nothing to be done to prevent it from spreading.  After harvest, I would immediately cut out the old floricanes.  The most full-proof approach to wiping out old inoculum would require complete removal and burning of the old canes.  Some producers hesitate to do this, so complete flail-mowing of the canes may work.  However, I would be careful to say that we don’t have research information to say that this completely destroys the inoculum.  I would tip or pinch prune where possible on the new primocanes, as opposed to large pruning cuts, and I would apply Pristine or Rally (make sure they are labeled for your state) after each day of pruning to prevent infection on the pruning cuts. Hopefully, this will break the cycle."