Botryosphaeria Twig Blight
This is a brief history and report of our experience with aronia dieback and death in our aronia berry plantation. In 2010 and 2011 we planted 5600 aronia plants on 10.5 acres. After good site preparation, 6-foot wide, 20-year woven geotextile fabric was laid down. The plants were then placed 6 feet apart in the row of fabric with 16 foot spacing between rows. In 2016 we first noticed a few plants dying, but thought it was "natural" mortality. In 2017 we became concerned because we were seeing more wilting of branches and even death of the whole plant. We figured we were loosing between 0.5%-1% of our plants. This does not seem like a lot, but of the 5600 plants we figure we lost about 40 plants last year. To us this is not an acceptable number.
In early July we sent a sample into the Forestry Diagnostic Lab at SDSU in Brookings, SD. They diagnosed the fungal genus "Botryosphaeria" as the culprit. Botryosphaeria Twig Blight can create cankers, dieback and death. It is not host specific but can colonize plant tissue through wounds, growth cracks, leaf scars and lenticels. It can also colonize dead branch tissue and move downward on the branch into healthy bark and sapwood. Spread occurs through air movement or splash dispersal of spores and can also occur through use of contaminated pruning tools.
According to the report from the South Dakota State University Forestry Diagnostic Lab, the best defense is to ensure plants are in optimal health by providing the appropriate cultural requirements. In other words, good weed control, air circulation, sanitation and fertility. Sanitation by pruning out dead wood is very important. Prune dead wood back to an area on the branch that is healthy (white to cream-colored when cut). Disinfecting pruning tools with rubbing alcohol between cuts may prevent the spread of Botryosphaeria inoculums on pruning tools.
If you have any questions concerning this twig blight, please feel free to contact me at firstname.lastname@example.org