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Occurrence and distribution of plant- parasitic nematodes of blueberry in Georgia

Ganpati Jagdale: University of Georgia

<div>In Georgia (U.S.), blueberry (<em>Vaccinium</em> spp.) currently grow on 12,141 hectares with a $255 million farm gate value, but the widespread occurrence of ring nematodes, <em>Mesocriconema ornatum</em> indicates blueberry replant disease (BRD), characterized by stunted growth and reduced yields, is a major limitation to continued production on existing farms. Since other plant-parasitic nematodes (PPNs) can also limit yield, we examined their occurrence on rabbiteye (RBE) and southern highbush (SHB) blueberries from 2012-2017. The UGA Nematode Diagnostic Laboratory received 241 soil samples (161 samples from SHB + 80 samples from RBE) from 50 blueberry farms across 17 counties. PPNs extracted from soil were identified to genus and densities were recorded. Ten PPNs including <em>Xiphinema</em>, <em>Hoplolaimus</em>, <em>Pratylenchus</em>, <em>Mesocriconema</em>, <em>Meloidogyne</em>, <em>Hemicycliophora, Helicotylenchus</em>, <em>Paratrichodorus</em>, <em>Belonolaimus</em> and <em>Tylenchorhynchus </em>were common to both RBE and SHB spp., but <em>Dolichodorus</em> and <em>Scutellonema</em> were associated only with SHB. The frequency of PPN occurrence varied by blueberry species; <em>Mesocriconema, Paratrichodorus</em>, <em>Pratylenchus</em>, <em>Xiphinema</em> and <em>Belonolaimus</em> occurrence was higher in RBE (87.5, 35.0, 12.5, 8.8 and 5.0%, respectively) than in SHB (74.5, 23.6, 6.2, 4.3 and 1.9%, respectively); in contrast, the frequency of occurrence of<em> Hemicycliophora </em>and <em>Meloidogyne </em>(6.8, and 5.0%, respectively) was higher in SHB than in RBE (2.5 and 1.3%, respectively). Frequencies of occurrence of <em>Helicotylenchus</em>, <em>Tylenchorhynchus</em> and<em> Hoplolaimus </em>were comparable in both SHB (35.4, 20.5 and 6.8%, respectively) and RBE (32.5, 17.5 and 6.3%, respectively). Knowledge of PPN species distribution can help growers develop control strategies that promote long-term control, reduce the impact of BRD and improve yields.</div>