Elucidating the Spread and Transmissibility of Blueberry Mosaic Virus, a New Disease of Blueberry in the Southeastern U.S.

View the project final report

Commodities

• Fruits: berries (blueberries)

Practices

• Animal Production: parasite control
• Crop Production: application rate management
• Education and Training: demonstration, extension, on-farm/ranch research, workshop
• Pest Management: cultural control, disease vectors, field monitoring/scouting, integrated pest management, prevention, sanitation
• Production Systems: transitioning to organic
• Sustainable Communities: local and regional food systems

After the first year of the project, there were major changes to the grower farm, and thereby to the scope of the project. Unfortunately the blueberry grower (location of BIMaV infected plants) destroyed all plants and sold the farm.  Because this project was based on a new (first report) disease for the SSARE region, the project did not follow the original proposal.

After Year 1 of the project, however, we determined several details about the virus. First, our analysis by qPCR determined that most plants within the field were infected, including asymptomatic bushes (those without symptoms, healthy appearance).  Next, our collaborating virologists, in their 2014 manuscript, characterized BIMaV as an ophiovirus, which is transmitted by soilborne parasites.  Both chytrids (true fungi) Olpidium spp. and polymyxa (protists) Polymyxa spp. and Spongospora sp. were found to transmit the virus.  Briefly, both vector groups are obligate (cannot survive without hosts), intercellular parasites of roots that produce motile zoospores.  Zoospores do not move far from host roots, and primary movement is extremely slow.  Thus, we have determined that natural virus movement is unlikely, even within a field planting.  Unless blueberry plants are positioned with overlapping roots, spread throughout a field can take decades.  It is then most likely that the virus spreads more rapidly through cuttings and movement of whole plants.  We determined that our cooperating grower obtained infected plants when establishing his orchard.  Virus details and findings are published in “A new ophiovirus is associated with blueberry mosaic disease by T. Thekke-Veetil et. al. 2014.”

During Year 2 of the project, we requested an alternative project scope and submitted a budget revision to reflect loss of the experimental farm and the new research findings. Overall, this virus BIMaV, like many diseases of blueberry of small fruit, are best managed by cultural practices, especially sanitation.  Thus, we revised our budget and objectives to increase disease-management outreach to assist blueberry growers and other fruit growers within the SSARE region with virus and disease management.

We created educational materials to produce fact sheets and video tools for Extension agents/educators, commercial growers, and residential hobbyists. Additionally we extended pest management and IPM training to a broader group of growers within the state by sponsoring educational events and workshops.  Finally, we surveyed blueberry growers for suspect infections and confirmed that, besides the test farm, BIMaV was only present in one other location in Kentucky. 

Objectives of this revised project included:

• Survey blueberry growers in Kentucky and determine whether there were other cases of BIMaV in the state.
• Expand disease management outreach to growers of blueberry and other fruit crops in Kentucky.  Shift focus to include sustainability and low-input disease-management strategies.
  • Develop a series of videos for online training - appropriate for county agents/educators, commercial growers, and backyard hobbyists
  • Develop a series of disease management fact sheets and publications that include a focus on cultural practices (as explained through pathogen biology), giving growers a better understanding of management options and approaches.