P-423 - Seasonal fluctuations of ring nematodes infesting rabbiteye and southern highbush blueberry cultivars in two fields in Georgia.

Blueberries (Vaccinium spp.) are cultivated on ~12,000 hectares in Georgia (U.S.), with a farm gate value of $530 million in 2023. Though defined treatment thresholds have not been established for ring nematodes (Mesocriconema ornatum), their widespread distribution, expansive population growth and well-known pathogenicity contribute to blueberry replant disease, characterized by stunted growth and reduced yields. Previous research has indicated that ring nematode populations peak between May and October in both southern highbush and rabbiteye cultivars. To develop a more defined population timeline, we examined seasonal fluctuations of these nematodes in rabbiteye (Brightwell, Ochlocknee, Powder Blue, Premiere, and Vernon) and southern highbush (Emerald, Farthing, Rebel, Star, and Legacy) cultivars at two blueberry farms in Appling and Bacon counties from 2011 to 2013. Though seasonal fluctuations varied by cultivar and location, seasonal variation in nematode counts for rabbiteye blueberries was generally not as pronounced as that observed with southern highbush blueberries. In addition, ring nematode counts associated with rabbiteye blueberry root systems remained relatively steady over time or even declined, whereas counts in southern highbush blueberries generally increased, sometimes dramatically, over the same timeframe. Southern highbush acreage has increased over the last 10 years, so ring nematodes have likewise increased in importance as to their potential impact on the Georgia blueberry industry.