Location: Fruit and Tree Nut ResearchTitle: Incidence and pathogenicity of plant-parasitic nematodes associated with blueberry (Vaccinium spp.) replant disease in Georgia and North Carolina Author
Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2013
Publication Date: 6/1/2013
Citation: Jagdale, G.B., Holladay, T., Brannen, P.M., Cline, W.O., Agudelo, P., Nyczepir, A.P., Noe, J.P. 2013. Incidence and pathogenicity of plant-parasitic nematodes associated with blueberry (Vaccinium spp.) replant disease in Georgia and North Carolina. Journal of Nematology. 45(2):92-98. Interpretive Summary: High ring nematode populations were found to be associated with commercially grown blueberries in Georgia that exhibited Blueberry Replant Disease (BRD) symptoms. Determining the host-parasite relationship of this ring nematode on blueberries and BRD is warranted. Greenhouse and field microplot studies were initiated to determine the host susceptibility and pathogenicity of this ring nematode on blueberry. Also, a survey of plant-parasitic nematode populations was determined in commercial blueberry replant sites in Georgia. Results indicate that ring nematode was the predominant nematode in blueberry replant sites in Georgia and that blueberry supported nematode reproduction, but was not pathogenic such that plant growth was severely suppressed in its presence. This research will be used by scientists, extension specialists, and growers who are developing management strategies and decreasing economic losses due to BRD in blueberry orchards in the Southeast.
Technical Abstract: Blueberry replant disease (BRD) is an emerging threat to continued blueberry (Vaccinium spp.) production in Georgia and North Carolina. Since high populations of ring nematode, Mesocriconema ornatum were found to be associated with commercially grown blueberries in Georgia, we hypothesized that M. ornatum may be responsible for predisposing blueberry to BRD. To prove this hypothesis, we tested the pathogenicity of M. ornatum, on 10-week-old Rabbiteye blueberries (Vaccinium virgatum) by inoculating with initial populations (Pi) of 0 (water control), 10, 100, 1000 and 10,000 mixed stages of M. ornatum /pot under both greenhouse (25 ± 2oC) and field microplot conditions. Nematode soil population densities and reproduction rates were assessed 75, 150, 225 and 255, and 75, 150, 225 and 375 days after inoculation (DAI) in both the greenhouse and field experiments, respectively. Plant growth parameters were recorded in the greenhouse and field microplot experiments at 255 and 375 DAI, respectively. The highest M. ornatum population density occurred with the highest Pi level, at 75 and 150 DAI under both greenhouse (P < 0.01) and field (P < 0.01) conditions. However, M. ornatum rate of reproduction increased significantly in pots receiving the lowest Pi level of 10 nematodes/plant compared to the pots receiving Pi levels of 100, 1000 and 10,000 nematodes 75 DAI. Plant-parasitic nematode populations were determined in commercial blueberry replant sites in Georgia and North Carolina during the 2010 growing season. Mesocriconema ornatum and Dolichodorus sp, were the predominant plant-parasitic nematodes in Georgia and North Carolina, respectively, with M. ornatum occurring in nearly half the blueberry fields sampled in Georgia. Other nematode genera detected in both states included Tylenchorhynchus spp., Hoplolaimus spp., Hemicycliophora spp., and Xiphinema spp. Paratrichodorus spp was also found only in Georgia. In Georgia, our results indicate that blueberry is a host for M. ornatum and its relationship to BRD warrants further investigation.