On-Farm Evaluations of Nonfumigant Nematicides on Nematode Communities of Peach

Experiments were established to evaluate the efficacy of currently available nonfumigant chemical and biological nematicides against nematode communities in peach orchards in two different geographic regions of South Carolina: the Upstate and Ridge. The treatments included sole or mixed application of two chemical nematicides (oxamyl and fluopyram) and a biological nematicide (Majestene) plus an untreated control. Ring nematode and lesion nematode were predominant in Upstate and Ridge orchards, respectively. Fluopyram was the most effective nematicide in the Upstate orchard, and it reduced plant-parasitic nematodes by 69% relative to the untreated control at 3 months postapplication. Similarly, fluopyram and oxamyl suppressed 74 to 87% of plant-parasitic nematodes in the Ridge orchard at 2 months postapplication. Significant effects of Majestene on plant-parasitic nematodes was not observed. Mixed applications of nematicides were also effective in suppressing plant-parasitic nematodes although the suppressions were not always significant from sole applications or the control. The chemical nematicides significantly reduced free-living nematodes in the first 2 months following their applications in the Ridge orchard, the reductions ranging from 60 to 79% relative to the control. However, free-living nematode populations quickly rebounded to the highest level in 3 months following the nematicide applications. Free-living nematode communities in the Upstate orchard did not experience any significant effects of nematicides until 4 months following nematicide application; at that time there was a 60 to 68% decline in populations. Results from this study suggest that the nonfumigant nematicides can only provide a short-term management of plant-parasitic nematodes in peach.