In the United States, from 2007 to 2016, there was a 70 percent and 106 percent increase in blueberry acreage and production, respectively. With such a rapid expansion, it is imperative to account for major pest problems adversely affecting the production. A study was done in the U.S. from 2015 to 2017 to determine the presence of blueberry viruses in major blueberry production and nursery areas of the country.
The viruses included in this study were:
- blueberry fruit drop (BFDaV)
- blueberry latent (BlLV)
- blueberry leaf mottle (BLMoV)
- blueberry mosaic (BlMaV)
- blueberry red ringspot (BRRV)
- blueberry scorch (BlScV)
- blueberry shock (BlShV)
- blueberry shoestring (BlSSV)
- blueberry virus A (BVA)
- peach rosette mosaic (PRMV)
- tobacco ringspot (TRSV)
- tomato ringspot (ToRSV).
The survey results indicated that there are hotspots for individual virus groups that normally coincide with the presence of the vectors. It was established that in the southeast, BRRV and BNRBV were the most widespread viruses.
The blueberry red ringspot virus has been reported across the range of highbush blueberries. The most apparent symptoms are reddish-brown ringspots with green centers (3-6 mm in diameter) on stems and red to purple spots on the upper surfaces of leaves (Figure 1).
The fruit can also have red blotches and infected bushes of ‘Ozarkblue’ produce deformed fruit. The vector has not been confirmed, but mealybugs have been associated with infection.
Diseased bushes have variable yield reductions from an apparent full crop to 25 percent crop loss. All infected bushes should be removed and destroyed. Highbush blueberry cultivars showing resistance are ‘Bluecrop’ and ‘Jersey’. The rabbiteye cultivar ‘Woodard’ is also likely to be resistant.
Many southern highbush blueberry cultivars are susceptible to the blueberry necrotic ring blotch virus. Symptoms appear as irregularly shaped, reddish-brown to black rings or blotches with or without green centers on both leaf surfaces (Figure 2).
Eventually, the spots may come together and cover the entire leaf. Symptoms are generally more prevalent on older leaves in the lower portion of the canopy. In severe cases, the disease may lead to premature bush defoliation.
Recent studies suggest that BNRBV does not infect southern highbush blueberry systematically and is not transmitted through vegetative propagation. The virus likely does not persist in plants after natural defoliation in the fall.
Fore more information, contact your county Extension commercial horticulture agent. Further information can be found in the following publications: